My due date, by the numbers

Today is my due date.

But the hours are ticking down and the likelihood of a punctual baby is just about zero at this point.

I realized this might happen as soon as I found out I was pregnant.  My mom had three of us.  We were all late.  Very late.  I was three weeks late, my older sister was as well, and my little brother was induced after two weeks post date.

My husband likes to remind me that he was four weeks early, so maybe we will just cancel each other out and this baby will come right on time.  But I am convinced that it has nothing to do with him and that I am doomed to follow in my mother’s footsteps and carry this baby around for another three weeks (or until the doctor induces me).

So what is a “due date” and does our genetic make up have anything to do with it? 

An article that was published this summer in Human Reproduction entitled “Length of human pregnancy and contributors to its natural variation” by Jukic and colleagues highlighted the importance of not putting too much weight on set due dates.  By analyzing 125 pregnancies and calculating gestation age based on ovulation date rather than the less reliable date of last menstrual period, the researchers found that gestation length can vary quite a bit.  Over a 37 day span, to be more specific.  That puts the due date range for normal gestation length at five weeks!  The median gestation length was 38 weeks and 2 days (keep in mind that due dates calculated by the last menstrual period would tack on about 14 days – so this would be around 40 weeks for those with true 28 day cycles).  Basically, it wouldn’t be crazy if this baby came in two weeks, rather than, say, tomorrow.  UGH.

They also tried to figure out what exactly was leading to shortened or lengthened gestation time.  Although they were quite limited with their sample size, from the data they were able to mine, they did find that events in the first two weeks affected timing of delivery.  This related to the time it takes for the little ball of cells to implant itself into the uterine wall and also how fast the hormone progesterone increases in the circulation after conception.

Again, this study was quite limited with its sampling.  Of the 125 pregnant women included, 95% were high school educated white women. There were very few smokers and the average age was 29.  So, someone like me, a 32 year old, educated white non-smoker might be able to glean information from this study, but it is hard to predict what other factors could contribute to gestation length unless you fit this profile.

With that said, in this study, the mother’s own birth weight did show some correlation with the gestation length.  Since this was not true of the mother’s adult weight, it can be inferred that there is something going on with inheritance from the mother – whether it be on the fetal side (e.g. growth rate) or maternal side (e.g. uterus size, pelvic size).

What about the father?  Will the hubs’ jump-the-womb-ship-early genes cancel out my late bloomer genes?

A 2006 paper “Maternal and Paternal Influences on Length of Pregnancy” published in Obstetrics and Gynecology by Lie, Wilcox and Skjeorven considered the input from both parents.  Here the researchers combed the Medical Birth Registry in Norway to gather birth data for two generations.  From this massive data set, they found that several aspects of delivery date could be correlated with heritable traits from both the mother and the father.  For fathers, a higher birth weight correlated with a decreased gestation length for their babies but this did not hold true for the mother’s birth weight (in contrast with the Jukic et al. study). The authors suggest that fathers may pass down their fast growing baby genes and thus influence the timing of birth. However, comparing parental birth weight with baby birth weight, both parents showed a positive correlation. In addition, the gestation length for both mothers and fathers correlated with the gestation length of their babies.

Although these two correlating factors, parental birth weight vs. offspring birth weight and parental gestation length vs. offspring gestation length, were evident for both parents, the effect was twice as strong for the mothers.  Therefore, the mother’s genes appear to have twice the influence over birth weight and gestation length than the father’s.  The authors predict this uneven influence from the maternal side suggests that the delivery decision is split between the baby’s input and the baby maker’s input.  Here is their logic – the baby is half dad genes, half mom genes.  If it was solely fetal input setting the date, that baby would follow exactly in the parents footsteps with no maternal leaning. But this is not the case, the maternal side is more predictive of the outcome (nearly two-fold), therefore, there must be some additional input from the maternal side. And similar to what was suggested by Jukic et al., this could have to do with the inner workings of the maternal body as it carries and grows a tiny human.

So, can we predict when this baby is going to make her debut?

Here is the basic baby prediction math –
1/3 = super early baby genes from the hubs (4 weeks early)
1/3 = super late baby genes come from me (3 weeks late)
1/3 = super late baby maker machine (again, 3 weeks late)

While this might seem like I should expect this baby to arrive a little more than a week past my due date, to complicate this math even more, the correlations between mother/father/baby gestation length and birth weight are not one to one.  According to the Norwegian study, an extra week in parental time is not the equivalent of an extra week in baby time.  Rather an extra week for mother’s gestation length = 1.22 days; for the fathers, one extra week = 0.58 days.

Revised baby prediction math – (keeping in mind that maternal input and baby input from mom’s genes are indistinguishable for the week:day ratio)
super early baby genes                          – 4 (weeks) x 0.58 (days) = -2.32 days
super late baby/baby maker genes          3 (weeks) x 1.22 (days) =  3.66 days
———————————————————— ————————————————————
average                                                                                     =  0.67 days

Ok, so even if I give myself a bit more credit, this math suggests that the baby should arrive… tomorrow.

But, then again, these are averages, based on correlations, and I am not Norwegian.

And, really, this baby will probably just come out whenever she damn well feels like it.

I want my N2O! (or at least the option)

Fellow American preggos, we are being deprived and we didn’t even know it!

In that inevitable conversation of whether or not we are going to want pain medication during our labor and delivery, the only option that really comes to mind is the epidural.

But for most women across the world, the epidural is not the only analgesic pain relief option.  WHAT!?

Our fun times Saturday activity a few weeks ago was an all-day birth class.  Pretty typical stuff, lots of vaginas and babies trying to fit through spaces that seem impossible to navigate.  But one issue that came up, almost in passing, really stood out to me.  A fellow student asked the instructor about the “gas option” for pain relief.  Pretty sure every woman in the room leaned in with a very confused look on her face – thinking, what the hell is “the gas option”?

As explained by our instructor, the question referred to nitrous oxide.  And, no, the gas option was not available at our hospital nor was it available at >99.99% of the hospitals in this country.  Fortunately for us, here in the Bay Area, if this is something we really wanted, we could just go across the bridge to UCSF, one of the FIVE hospitals in the US that offers this option to laboring mothers.  Going across the Bay Bridge while in labor is not my idea of fun so I’ll forgo this opportunity, but I was intrigued.

Apparently, nitrous oxide (N2O, also known as “laughing gas”) is the most commonly used labor analgesic in the world – used by more than 60% of laboring women in the UK, 70% in Sweden!

First, how does it work?  It seems that the best “dose” of N2O is a 50:50 mix of nitrogen and oxygen, mixed immediately prior to inhalation.  It is self-administered – the woman holds up the mask and takes a puff any time she wants.  How it works, physiologically, is a bit murkier but the overall gist is that it effects the way pain is perceived in the brain. It is very temporary – it takes about 30 seconds to have an effect and it is cleared from the system within minutes.  It does not accumulate, it only goes through the lungs and never involves the liver so there are no bits left over from metabolism.

So how good is nitrous oxide for pain relief during labor and why is it not available to most of us here in the US?

A 2002 review by Dr. Mark Rosen, an obstetrician at UCSF, pointed out the basics of the benefits and the absurdity of the concerns [1].  In the review, he evaluated every scrap of scientific and clinical evidence he could find about the use and the study of nitrous oxide in labor pain management. Overall, what he found was that the literature was lacking.
(A more recent review demonstrates that this lack of information and sound, well-controlled studies is still a problem [2].  But I can imagine it is pretty difficult to ethically give a woman in labor a placebo pain medication, so designing that perfectly controlled experiment can be a bit tricky.)

With that said, there were some key points that Rosen could assert.  First, the concerns are stupid (my words, not his).  For the actual labor component, there is far less to worry about than pretty much any other medical option – N2O does not affect uterine contractions and it does not affect the newborn.  It can cause drowsiness – but the beauty of the self-administered system is that if the woman gets drowsy or starts to pass out, she drops the masks, inhales fresh air and, voila! drowsiness from the N2O is gone.  The main concerns really center around the gas getting out into the room and into the world.  Escape into the room exposes the health care workers BUT most of our hospitals these days have pretty damn good ventilation systems and the units for administering the N2O have scavenging systems in place to grab the escaped gas before it accumulates.  Plus, the mask only releases N2O when the patient takes a pull.  The second escape concern is that N2O is a potent greenhouse gas.  But as Judith Rooks points out in her 2007 article in the Journal of Midwifery & Women’s Health [3] “…it is clear that medical uses of N2O are a very small part of the problem. In summary, the global warming risks are valid but low relative to many less vital uses of N2O, including NASCAR races, the followers of which, however, have a more effective political voice than pregnant women in the United States, who might want to use N2O but who don’t even know about it as an option”.  Sing it, Judith!

Second, for the pain, well, let’s just say it’s no epidural.  According to Rosen, it has not been shown to be a potent labor analgesic, it does not eliminate pain, but it can provide “a sense of relief”.  And there are ways to improve the effectiveness of the pain relief; for example, learning how to time inhalation with contractions since it can take up to 30 seconds to kick in and does not last long after the mask is removed.  But, it is safe and it is adequate and most women who labor with access to N2O do not end up going for the stronger stuff.

As someone who studies stress, I am reminded of a classic stress experiment involving two rats, two tethered cages, two electrified floors, and one off lever to push. The electrified floor switches on unexpectedly, give both rats a little shock, and one of the rats has the ability to stop this pain by hitting the lever in its cage.  Same shock, same timing, same pain, but one rat has a sense of control over this pain and the other does not.  It is this sense of control that appears to be what saves this rat from the stress of the situation while the other rat turns into a stressed out mess (non-scientific terminology, of course).

By giving a laboring woman the option, the mask to hold in her hand to self-administer a little hit of possible pain relief, we are giving her control. We are lowering the stress of the situation. Why? WHY? Is this option not widely available or even known about in the US? The birth class instructor seems to think that it has something to do with money – no one makes money from an off-patent, inexpensive, old school gas option so who is going to promote it?  If this is actually the case, it would be another incredibly sad and f-ed up thing about the American Health Care System.

Personally, I am going to try to get through as much of labor as physically possible without medication.  I’m honestly curious about what it all feels like (all the mamas out there have one eyebrow raised with deep insight and skepticism).  But, man, I do wish I had the option of hitting some laughing gas rather than only having the option that involves a tube feeding nerve knockout juice past my spinal column.

1. Rosen MA. (2002) Nitrous oxide for relief of labor pain: A systematic review. Am J Obstet Gynecol;186(Suppl 5):S131–59.

2. Likis FE, Andrews JA, Collins MR, et al. (2012) Nitrous oxide for the management of labor pain. Comparative effectiveness review no. 67. AHRQ publication no. 12- EHC071-EF. Rockville (MD): Agency for Healthcare Research and Quality.

3. Rooks, J. P. (2007) Use of Nitrous oxide in Midwifery Practice – Complementary, Synergistic, and Needed in the United States. Journal of Midwifery & Women’s Health; 52 (3): 186-189.

Beyond the baby monitor

baby monitoring

Did I mention that I am currently part of a science experiment?

Sure, there is a sample size of one so I can’t promise a powerful data set coming out that would revolutionize how we think about pregnancy but maybe…

Anyway, as soon as I announced my pregnancy to the world last spring, a fellow postdoc, who is interested in biological rhythms in humans and other furry creatures, immediately jumped at the chance to make me a lab rat.  “Can I wire you up?”, he asked.

My first thought was that I was going to have electrodes attached all over my body for the next six months.  So, of course, I responded “Hell yeah!”

How could I resist?

Luckily, I do not have to wear multiple electrodes on my increasingly uncomfortable body, but I have been wearing an armband with a little data collector attached to it.  It is actually marketed for the much more lucrative fitness and weight loss industry (technically an “on-body monitoring system”) and it monitors aspects of everyday life from steps taken (your standard pedometer) to calories burned (changes in body temperature) to sleep patterns (are you laying still or moving around a lot).

So far, we have only peeked at the output with plans to really get into the data once the womb baby has joined the world. My predictions – my sleep will get progressively crappier (I can see that 3am wake up, toss and turn, and every additional midnight trip to the bathroom), the number of steps I will take will decrease and calories burned will …. well, that one will be interesting (Can we see if I’m actually “eating for two”?)

While I’m quite interested to see what information my friend can actually mine from this data set, I don’t have my hopes up too high.  It feels very limited.

But is there a way to glean even more information from our pregnant bodies?  A way to glean more information about this tiny stranger that we are building and carrying around inside our body for 9+ months? 

Looking around for this kind of technology it appears that there are quite a few things out there for understanding our own bodies… to some degree.  For example, fitness buffs and not-so-buffs looking to get into shape are using things like BodyMedia (what I currently have strapped to my arm), FitBit, and Jawbone UP.  Again, think fitness, these guys are really out for quantifying your physical output and come with handy apps to also keep track of your eating patterns, weight, etc.  They also claim to measure sleep “efficiency” but really they just rely on an accelerometer to say “ooh, movement! fitful sleep!” or “no movement, must be cruisin’ in deep sleep”.  Interesting, but not completely insightful (and maybe not even that accurate!)

In addition, there has been a burst of technology coming out to monitor babies’ bodies as well. Mimo, comes with a cute little “turtle” that attaches to a special electrode equipped onesie and tracks sleep trends and development and can also alert the parents about changes in breathing, sleep position, temperature, and waking patterns. Owlet, is a little foot cuff thing that tracks baby heart rate and oxygen levels.  Sproutling is another wearable for the baby’s ankle that monitors heart rate and breathing along with a base station that measure temperature and humidity in the room. Teddy the Guardian by iDerma is a special teddy bear that will take the kid’s temperature and oxygen saturation.  This one requires the kid to actually grab onto the bear’s paw for a reading.  With a name like Teddy the Guardian, I would actually be a little frightened that the thing might grab back, Poltergeist-style, so I don’t know about this one.

It is hard to escape the fact that we live in a world revolving around technology.  Through our keyboard, we literally have information at our fingertips (although, I must say, I am not impressed with much of the pregnancy “advice” coming up on Google).  Is monitoring our own bodies and our babies’ bodies the next step in the fully informed patient generation?

Is having access to this level of knowledge about your baby empowering or neuroses enabling?

What do we need to know?  What do we want to know?  Where is the line?

What can we learn about pregnancy if devices are available or adapted for pregnant women to track biological rhythms, changes in womb baby’s movement, heart rate, sleep cycles?

What can we learn about babies when more parents opt to go beyond the baby monitor and keep track of biological details of daily and nightly patterns?

Is this a pediatrician’s worst nightmare or previously unattainable dream?

As I prepare to make this transition from pregnant scientist to mommy scientist, I have just a few more questions for those of you who have gone through all of these stages already.  From what is available and what might become available, what is one thing you wish you could have monitored at any point during pregnancy or infancy?  What kept you up at night, checking on the baby (besides the screaming, feeding, changing part)? Would a little bit of tech have brought you peace of mind?  Or made you crazy?

And what the hell is the point of TweetPee?

Please leave comments below!

Tea for two?


I am a scientist. But I also work in Berkeley, CA. And it was only a matter of time before these worlds collided…

Let’s talk about the science behind a very popular pregnancy herbal supplement – Raspberry Leaf Tea.

(My prenatal yoga instructor is not going to be happy with me.)

Though I proudly bought my Prenatal Vitamins, Ovulation tests, and pregnancy pee sticks, I hid my “Mother to Be” tea underneath a red pepper on the supermarket conveyor belt the other day.  Yes, I bought the tea but I am still conflicted about buying into the concept that a tea can magically (uh, I mean biologically) strengthen a uterus.

In addition to the gushing words from my yoga instructor, the internet offers up unlimited gems about the stuff.  These words of wisdom range from the very appealing –  “It strengthens the uterus and pelvic muscles which leads to shorter and easier labors” to the anecdotal –  “…my sister’s sister took it at 35 weeks and had her baby within 48 hours” to the very confident “Has been shown to concentrate the effects of contractions to make them more effective

Alright then, challenge accepted! Time to dig up some scientific evidence for these claims.

So, can raspberry leaf tea do all these amazing things the internet claims it can: strengthen the uterus, shorten labor, decrease assisted delivery, and so on?

Well, despite this supplement being a fan favorite over in the midwife community (63% of American midwives recommend this supplement to stimulate labor [1]), overall it seems like the jury is still out as to its pro’s and con’s.

A very comprehensive scientific literature search by Holst et al. in 2009 [2] found only six studies testing the effects of the tea in a lab, with non-human or petri dish subjects, and only five studies that took place in the clinic. I do want to note that the small number of studies unveiled was not for lack of trying – these authors including an obscure paper from 1941 that only included three women!  Anyway, the lab studies were mixed.  Overall, raspberry leaf tea was shown to facilitate more rhythmic contractions in uterine tissue but also showed conflicted toning and relaxing effects.  The five clinical studies did not reveal any strong effects of the elixir (positive or negative) in humans.  Some studies did show a shorter first or second stage of labor but the tea only knocked off a few minutes (wow!) and one study showed shorter gestation length… but only by a couple of days (insert more sarcastic enthusiasm).

After Holst and colleagues published their efforts combing the literature, another lab study [3] was conducted to directly test uterine contractions in the presence of raspberry leaf tea in vitro (outside the body).  When applied directly to uterine tissue from non-pregnant rats, raspberry leaf tea had no effect on uterine contractibility.  However, when the researchers stuck a pregnant rat’s uterus in a petri dish with some the tea – BAM! – the cellular response rivaled that of Oxytocin.  Oxytocin, among the many wonderful things it can do during birth, is the main hormone in charge of making sure the uterus steps up and does its job to help get baby out into the world.  The researchers then tested whether raspberry leaf tea played Oxytocin’s little helper in this process.  With only six test subjects, however, they found results split in two directions:  half of the test subjects showed that oxytocin-induced contractions were augmented with raspberry leaf tea, but the other half showed the same augmentation followed by inhibition of contractions.  Hmmmm.  At the end of the day, though, the authors did not even want to put weight into their own findings (which I actually found quite promising so I was a bit bummed).  They concluded that since humans are unlikely to get the same dose that they used on their rat uteri, this effect is probably not translatable to the intact, in vivo uterus of your average pregnant women.

Now for the potential adverse effects.  Well, fortunately, there were mostly no adverse effects noted. However, there was one study that found odd trans-generational effects [4].  That’s right, drinking raspberry leaf tea while pregnant may affect your baby and your baby’s baby.  In this study, mother rats were fed raspberry leaf extract every day from conception to weaning.  The babies of these mother rats showed signs of early puberty and the babies’ babies showed greater growth restriction.  Important to point out, though, these rats were consuming raspberry leaf extract throughout the entire pregnancy.  I cannot put a percentage on the number of female humans consuming the tea throughout pregnancy but I am guessing more women are taking it primarily when they start to hit that “holy crap, I have to push out a screaming child!” stage.  My unscientific analysis of pregnant friends puts this stage somewhere between the second and third trimester but rarely during the first, when the developing womb baby is most likely to be affected by what we are putting into our bodies and when these effects may affect the womb baby’s egg babies.  Of course, more studies are needed before we can conclude that this is or is not a scary potential result of raspberry leaf consumption.

As for those benefits –

Sorry, internet, but I have to side with the scientist buzzkills, Holst and colleagues, when they state – “The fact that the product has been in traditional use for decades does not constitute evidence”.  There simply are not enough studies to back up the claims that raspberry leaf tea is a pregnancy super juice.  

With that said, in honor of full disclosure, I must admit that I have a steaming pot of “Mother to Be Tea” sitting next to me as I write this.

Yup, there will always be a tiny part of me swayed by the fact that it worked for somebody’s sister’s sister.

1. McFarlin, B. L., M. H. Gibson, et al. (1999). “A national survey of herbal preparation use by nurse-midwives for labor stimulation: Review of the literature and recommendations for practice.” Journal of Nurse-Midwifery 44(3): 205-216.

2. Holst, L., S. Haavik, et al. (2009). “Raspberry leaf – Should it be recommended to pregnant women?” Complementary Therapies in Clinical Practice 15(4): 204-208.

3. Zheng, J., M. J. Pistilli, et al. (2010). “The Effects of Commercial Preparations of Red Raspberry Leaf on the Contractility of the Rat’s Uterus In Vitro.” Reproductive Sciences 17(5): 494-501.

4. Johnson, J. R., E. Makaji, et al. (2009). “Effect of Maternal Raspberry Leaf Consumption in Rats on Pregnancy Outcome and the Fertility of the Female Offspring.” Reproductive Sciences 16(6): 605-609.

The nose knows


Fellow scientist and good friend, Dr. C, has already made her way through this whole pregnancy thing and has been my sounding board for all things bump related.  I must admit, I am extremely jealous of those pregnancy superpowers – super smell, super taste – bestowed upon many a pregnant lady that seem to have missed my expanding body.  But then again, if this oversight also provided that sweet bypass from the cookie-tossing gods, I will take it. 

Dr. C., however, was lucky… or not so lucky… to have experienced the full on rewire –


It’s a bird! It’s a plane! No, it’s a heightened rhinological olfactory manifestation!

Or, in plain English, a heightened sense of smell…

Honestly, I think my nose knew I was pregnant before I did.

It was a beautiful, San Diego Saturday. I was relaxing on the couch working on my computer (a.k.a. guiltily watching the latest reality show…), when my husband decided to make himself a tuna fish sandwich.

Within moments of opening the tuna can, the fishy aroma hit me like a Mack truck. I ran for the bathroom and promptly threw up in the toilet. And a little around it.

“Whoa. It must have been something I ate,” I said to a very surprised husband…

It wasn’t until weeks later I figured out that I was pregnant.  By then, I could, from our apartment, smell what our neighbors three doors down were having for dinner.

Was I imagining it?

Much like a spider bite gave spiderman his spidey sense, did a German shepherd bite me?

Target knew I was pregnant before I did, too. I started to get all these coupons for diapers and nursery furniture. I have no idea what changed in my buying habits to tip them off, but one secret experts posit is that expectant moms tend to opt for the scent-free lotions! [1]

So, what is it about smell that changes for pregnant women?

In a study by the National Geographic Smell Survey [2], a whole bunch of women (290,838 women to be exact, of whom 13,610 were pregnant) reported on their sense of smell. The pregnant women claimed they couldn’t smell as well as those that were not pregnant, yet they performed better on one of the smell tests they took.  More recent studies showed that women did self-report to have a better sense of smell while pregnant [3] [4], or at least experienced a change in smell [5].

But what yours truly says to all of those studies is: brave be the soul that can endure the smell of pungent fish while pregnant.

So, how and why do we get these super smell powers when we’re expecting?

During pregnancy, the hormone estrogen increases to help with a whole host of events that occur.  It’s been shown that it is this increase in estrogen that activates that crazy smell superpower.

Why? Back when we were all running away from the dinosaurs (ok, that never really happened, but a looong time ago), a heightened sense of smell may have been beneficial to the health of mama and baby. Those that ate the stinky, spoiled foods or other such toxic agents got very sick, couldn’t maintain pregnancy, or even died. Those that could smell out bad food and avoid it lived, passed on this beneficial smell trait to their daughters, who had daughters that could smell, who had daughters that could smell, and so on.

Because of this, women in general, as compared to men who maintain lower levels of estrogen, are supposed to have a better sense of smell and of taste. After all, taste is very much linked with smell [6].  Think about it – your nasal passageways and your mouth are connected – which you most likely tested unknowingly as a child when you drank chocolate milk, laughed, and it came out of your nose.

With that appetizing thought…

Have you ever watched the Food Channel? Whenever they have those awesome cooking competitions, sometimes the women judges disagree with the guy judges about which competitors’ pistachio-encrusted crème brulee tasted better. The women judges will proclaim themselves, because they are women, as having the more sensitive palate (and thus are right about their choice of most delectable brulee).

Gentlemen, I’m afraid the ladies have you on this one. Ten points for estrogen!

So, in this sense, when women get pregnant and have what an old science teacher of mine called “oodles and gobs” of estrogen, their smelling and tasting powers cannot be rivaled.

In fact, my pregnant ladies, you make the best wine tasters! Now, stay with me here – wine connoisseurs from Tesco’s HQ in Hertfordshire claim pregnant women make the best tasters [7]. They even put out a nationwide call for pregnant women to help them with in-store tasting and called it, Operation: Cot du Rhone!

Of course, some doctors came out of the woodwork shouting, “Alcohol BAD!” [8];

But back to the big picture: whether a pregnant woman’s heightened estrogen and associated sense of smell leads her to puke at a whiff of tuna or become the greatest wine connoisseur in the land, I think we all can genuflect in awe and wonder for these newly (and temporarily) acquired superpowers of the Nose.


1. Hill, K. How Target figured out a teen girl was pregnant before her father did. 2012. Forbes.

2. Gilbert, A.N., Wysocki, C.J. 1991. Quantitative assessment of olfactory experience during pregnancy. Psychosom Med. 53:693-700.

3. Cameron, E.L. 2007. Measures of human olfactory perception during pregnancy. Chem Senses. 32:775-782.

4. Ochsenbein-Kolble, N., von Mering, R., Zimmermann, R., Hummel, T. 2007. Changes in olfactory function in pregnancy and postpartum. Int J Gynaecol Obstet. 97:10-14.\

5.  Nordin, S., Broman, D.A., Olofsson, J.K., Wulff, M. 2004. A Longitudinal Descriptive Study of Self-reported Abnormal Smell and Taste Perception in Pregnant Women.” Chemical Senses. 29:391-402.

6. Kuga, M., Ikeda, M., Suzuki, K., Takeuchi, S. 2002. Changes in Gustatory Sense During Pregnancy. Acta Otolaryngol. 122:146-153.

7.  Sample, Ian. 2004. Do pregnant women really make the best wine tasters? The Guardian.

8. Tesco wine tasting plans slammed. 2004. BBC.

Mmmm, sweet sweet orange-flavored diagnosis

I drank the Kool Aid last week.

Crossed over into the third trimester and went in for the oh-so-pleasant glucose tolerance test to check for gestational diabetes.

As I choked down 75 grams of orange flavored liquid glucose, I thought to myself – “Who the hell came up with this pregnant woman torture test?  You want me to fast and then drink something thick and sugary, continue to not eat or drink for two hours all the while pricking me like a pin cushion?  Can’t you see that I’m pregnant?  And, wait…why am I doing this again?”  Really, how good is this one test at diagnosing and providing information for treatment?

To answer that first question – we can thank John B. O’Sullivan and Claire Mahan for developing the criteria to use with the oral glucose tolerance test in 1964 to screen for Gestational Diabetes Mellitus (GDM).  And yes, forty years later, we still pretty much use the same test and the same criteria.

For the second question – digging through the scientific literature on this quest was a bit overwhelming and unsatisfying. Luckily, the National Institutes of Health recently put together a panel of experts for a Diagnosing Gestational Diabetes Mellitus Conference to tackle the scientific literature and give their expert opinion on the current status of diagnosing this disease in pregnant women.

From the statement issued, it seems that the discussion centered on whether or not to universally adopt a newer test pushed by the International Association of Diabetes and Pregnancy Study Groups (IADPSG).

Two main tests are currently used across the world:
Two-step test – Pregnant woman drinks 50g glucose drink and has a single blood draw after an hour. If her glucose rides high, she has to go back and get the 3hr 100g test.  This second test is strictly on an as-needed basis; only 14-23% of patients will need this diagnostic follow-up.
One-step test (promoted by IADPSG) – Pregnant woman goes in fasting, gets blood drawn, drinks 75g glucose drink, gets blood drawn at 1 hour and 2 hours.  If any of her glucose levels ride high, for any of the three time points, she is diagnosed with GDM.  This is the test that I was given.

For the two-step test, 5-6% of mamas-to-be will get diagnosed with GDM.
The one-step test is more prone to false positives.  With only a one day, one time snapshot of sugar levels, this test does not exactly take into account the fact that results from the same woman can vary as much as 25% at different times. It is expected that this one-step test, with its current criteria, will diagnose 15-20% of pregnant women with GDM.

Considering this difference between the tests, the NIH panel statement focused on weighing the costs of underdiagnosing versus overdiagnosing GDM.

What are the risks of underdiagnosing?

First, what are the general risks of GDM?  A study published in The New England Journal of Medicine entitled “Hyperglycemia and Averse Pregnancy Outcomes” by the HAPO Study Cooperative Research Group compiled data from over 25,000 pregnant women from 15 birth centers across 9 countries. All the women were given the one-step test and their glucose levels at any of the three sample points (fasting, 1 hr post glucose, 2 hrs post glucose) were correlated to primary risks (e.g. birth weight >90th percentile) and secondary risks (e.g. birth injury). They found that increasing relative glucose at any of the time points increases the likelihood of birth weight above the 90th percentile and the likelihood of c-peptide levels in the cord blood (a marker for insulin resistance in the baby) being above 90th percentile.  There was also an increased risk of premature labor, preeclampsia, and birth injury.

Two things to consider though.  One, these relationships are observational – correlations rather than causal effects. Therefore, outcomes cannot be clearly attributed to the increased glucose levels in the mother.  Second, these increased risks and likelihoods have a linear relationship with glucose levels. There is no threshold so there is no easy cutoff point above when these levels cross into risky territory. Where do you draw the line for diagnosis?

Considering this diagnostic moving target, would all women at any range of GDM benefit from treatment?

Back to the NIH panel members, who pored over the literature for evidence and found…. well, there is really no consensus on the benefits of treating diagnosed GDM.

For the mother, treating GDM can decrease hypertensive disorders by 40% (one plus).  For the baby, treatment decreases the likelihood of bigger babies (also a plus, BUT, at a 6% decrease, I’m not too impressed).  Beyond these effects, there is no conclusive evidence that treatment decreases the other risks.  Also important to note, these studies are based on treatment of women diagnosed by the more stringent two-step test.  These are not women with mild GDM.  We have no freaking clue how/if treatment will benefit those falling in the “hmmm…maybe” range.

What are the risks of over-diagnosing?

For one, being told that you’re pregnancy isn’t going as swimmingly as you thought and that you have to be on high alert, pricking your finger all the time to test your blood sugar could certainly cause a bit of anxiety.

Additional concerns discussed by the NIH panel:
One, this diagnosis has been linked to higher induction rates.  Two, having “Gestational Diabetes Mellitus” on your chart could send you down a C section spiral – increased fetal and maternal monitoring which can then lead to increased false alarms which can lead to increased failed induction which can lead to increased cesarean section.  Three, it can result in increased neonatal care, separating mama from baby unnecessarily.  And, four, with all the heightened intervention, it can lead to increased direct and indirect health care costs.

Overall, the NIH panel warns that “overdiagnosis of GDM may lead to the ‘medicalization of pregnancy’ which transforms an otherwise normal pregnancy into a disease”


As the panel concluded, it is too early to universally adopt the one-step approach. Increased diagnosis will lead to increased cost and intervention without a clear cut benefit to the patient.

Basically, the answer to my second question is – the jury is still out.  

I’m not sure how much say a woman can have in the type of test she is administered.  If I had known all of this before, I might have asked if the two-step test was an option.  Luckily my levels were totally normal.  But I guess I could have just been caught on a good day at a good time….  Phew!

Overall, I agree with the NIH panel, why risk unnecessarily stressing out a pregnant woman?  We have the rest of our lives to stress about all the ways we will screw up our kid!

Worrying about Whooping Cough

Recently, one of my mom’s friends had a new grandchild and this friend’s daughter, who works in a neonatal care unit, requested that all family members get a Pertussis vaccine.

My mom wanted to know if this was something she needed to worry about too.

Pertussis is the fancy name for Whooping Cough.  And, until a few years ago, I honestly thought that Whooping Cough was a thing of the past.  Something that your computer game children caught and died from when electronically traveling on the Oregon Trail.
And then there was an outbreak of the disease in California (and other parts of the country) in 2010.  Thousands of children got sick. Ten infants died.  Frightening stuff and no longer bound to the confines of a pixelated computer screen.

In the US, Whooping Cough outbreaks are actually more common that I would have thought. And this disease is cyclical: outbreaks tend to occur every 3-4 years.  I guess we’re due!  Yikes.

So, back to the query from my mother.

Do I (and my family) have to get vaccinated for Whooping Cough/Pertussis?

An info sheet about the Tdap vaccine (Tetanus-Diptheria-Pertussis) that I received from my doctor addresses this question very vaguely.  The info sheet only suggests women who “have never had a dose of Tdap” get one.  Well, my mom definitely made sure I got all of my shots as a child and I know that I have had a tetanus booster in the last 10 years (I am accident prone… especially around sharp metal objects!) but I cannot tell you the last time I had a booster that covered all three.

Taking a less ambiguous approach, the CDC recommends that ALL pregnant women get a Tdap vaccine during the 3rd trimester. As the CDC notes 30-40% of the cases involving infected infants in the 2010 outbreak could be directly attributed to the mother.  70+% could be attributed to any family member.  The “cocooning” strategy that my mom’s friend was subjected to addresses this level of prevention.  “Cocooning” is when all persons who may be coming into contact with the pre-vaccine baby (this vaccination series starts at 6-8 weeks of life) also gets vaccinated.  Apparently, vaccination as a child is not enough, your immunity to the disease starts to wear thin after about 10 years so you may still catch the disease and unknowingly pass it along to the non-vaccinated baby.

But the cocooning method seems a bit extreme to me.  And I feel justified in saying that given that an article in Clinical Infectious Diseases entitled “Infant Pertussis: Is cocooning  the answer?” appears to agree.  The authors note that cocooning just isn’t practical and a bit too “logistically complicated” to provide the benefits that a simple maternal immunization would allow [1].  So, I think I just might take the “don’t come around if you are sick” and “don’t cough on my baby” approach instead of making everyone around me double check their vaccination history.

You are off the hook, mom.

But what about that maternal immunization/booster?

The recommendation for all pregnant women to get the shot before or immediately after having the baby is a straightforward approach to making sure the mother will not catch and transmit Whooping Cough to the new bundle.  Holding off on the vaccine to watch and wait for an outbreak isn’t the most effective strategy – it takes about two weeks for the antibodies to build up to amounts that would effectively fight the illness and limit its spread.

But there is another reason to get the shot during pregnancy.  Recent research has suggested that a Tdap vaccination during the third trimester can actually confer some degree of protection to the infant for when it enters this dangerous, disease ridden world.  Studies have shown evidence for increased Pertussis antibodies in the cord blood and in the circulation of infants whose mother’s were vaccinated as compared to infants of unvaccinated mothers [2].  Effectively, this allows a brand new baby to have some antibody fighting power against Whooping Cough even before the first vaccine series initiates baby’s self-built antibody stockpile.

Important to note, though, there does appear to be a Goldilocks sweet spot for the timing of getting this shot:  post-birth may be too late but before the third trimester may be too early.  Getting the vaccine pre-conception or early in the pregnancy does not confer the same placenta-hopping-antibody benefits [3].  That’s right, if you are cooking up your second, third, fourth baby, you will still need to get that arm poked if you want to potentially pass along the benefits of the vaccine.

What about negative side effects?  An extensive review of reports sent in to an oversight body, VAERS (Vaccines Adverse Event Reporting System) turned up absolutely nothing of concern for maternal/infant/fetal outcomes post Tdap vaccine [4]..

So, I’m pretty convinced.  I think that passing along a bit of immune system fightin’ power against any potential Whooping Cough outbreaks seems more practical than hanging a sign around the baby’s neck that reads “Please do not cough on my baby”.


But, seriously, please do not cough on my baby.



1. Munoz F, Englund J,. Infant pertussis: is cocooning the answer? CID 2011;53:893–6.

2. Leuridan E, Hens N, Peeters N, de Witte L, Van der Meeren O, Van Damme P. Effect of a prepregnancy pertussis booster dose on maternal antibody titers in young infants. Pediatr Infect Dis J 2011;30:608-10.

3.Healy CM, Rench MA, Baker CJ. Importance of timing of maternal combined tetanus, diphtheria, and acellular pertussis (Tdap) immunization and protection of young infants. Clin Infect Dis 2013;56:539-44.

4. Zheteyeva YA, Moro PL, Tepper NK, et al. Adverse event reports after tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccines in pregnant women. Am J Obstet Gynecol 2012;207:59, e1–7.