Tag: Pregnancy

Should you Get the COVID-19 Vaccine if You are Pregnant or Trying To Conceive?

As soon as COVID-19 vaccines arrived, conspiracy theories about harmful effects began spreading. Perhaps shrewdly, several of these conspiracy theories target reproductive age women, claiming falsely, for example, that the vaccines will impair fertility or, if they are already pregnant, harm their baby’s placenta. 

This is partly the fault of the Moderna and Pfizer, the producers of these vaccines, who excluded pregnant women from their clinical trials, despite leading maternal health organizations like the American College of Obstetricians and Gynecologists all but begging them to test their vaccines in pregnant women. Naturally, the antivax movement was more than happy to step into the resulting data void. 

So here’s what I think pregnant women should know, if they have the chance to get one of these vaccines: Get the vaccine. Get it as soon as it is offered to you. 

If I were pregnant, I would absolutely get one of the two currently available vaccines (Pfizer and Moderna), for a few reasons.

Continue reading “Should you Get the COVID-19 Vaccine if You are Pregnant or Trying To Conceive?”

An early beta hCG test does predict your risk of miscarriage

That first glimpse of two pink lines–can it be?–and your heart start to pound with excitement. You’re pregnant!

But after a few moments of celebration, you descend back to earth. Okay, you’re pregnant, but for how long? Will this pregnancy stick?

You have entered a new, more hopeful limbo than the much bemoaned two-week wait. But it’s still no picnic.

We all know that miscarriage is very common, especially early in pregnancy. And for most women, good info about viability does not come until the first ultrasound, usually performed at 8-10 weeks.

Undergoing fertility treatments is less fun than a hangover. But they have one silver lining: Once pregnant, you receive information about your chances of a healthy pregnancy much earlier, from your “betas”–blood tests of your beta hCG (Human Chorionic Gonadotropin) levels.

Continue reading “An early beta hCG test does predict your risk of miscarriage”

Back sleeping and stillbirth revisited: A reason for caution, or a few extra pillows

As longtime readers of my blog know, in 2011, carrying my first child, I became obsessed with the question of whether pregnant women could lie on their backs–either for short periods of time, such as during a yoga class, or while asleep at night.

Several OBs told me to avoid lying on my back. But their justifications were murky, and their advice conflicting. Not a one could point to a single published study backing this advice up. And when asked at what point in pregnancy I needed to start avoiding back sleeping, their answers were all over the place. One told me it was verboten from 4 months on, another from 5 months on, and the third claimed I should worry only in the last month or so.

Sleeping with a bowling ball-sized stomach is challenging, to say the least. At the same time, groundless sleep prohibitions with vague but terrifying warnings that you might harm your baby are immensely frustrating, and yet almost impossible to disregard.

Continue reading “Back sleeping and stillbirth revisited: A reason for caution, or a few extra pillows”

Five little known facts about pregnancy weight gain

Even for the most body-secure among us, gaining anywhere from 20 to 40 pounds during pregnancy is no picnic. Sure, we have days where we are full of energy and glowing and ready to flaunt our adorable baby bumps. But we also have days, especially in the third trimester, where we feel less like mama-goddesses and more like sweaty, frumpy, nothing-fits-anymore messes.

To take the edge off, I turned to the Institute of Medicine’s (IOM) report on pregnancy weight gain, which provides the evidence base for their widely-referenced weight gain guidelines:

  • Underweight: Gain 28-40 pounds
  • Normal weight: Gain 25-35 pounds
  • Overweight: Gain 15-25 pounds
  • Obese: Gain 11-20 pounds

Some of what I learned from their report was outright reassuring, like that a sudden bump up in weight in the second trimester is common and does not imply that you will continue to gain weight at a fast clip. Other facts, like that 15-30 percent of the fat gained during pregnancy goes straight to our thighs, were less reassuring. Continue reading “Five little known facts about pregnancy weight gain”

Light Drinking During Pregnancy: 7 Things You Need to Know

Last year, the CDC ignited a firestorm of criticism by stating that women should “stop drinking alcohol if they are trying to get pregnant or could get pregnant”, and–because an estimated 50% of pregnancies in the U.S. are unplanned–any woman who drinks alcohol should use birth control.

“Its [the CDC’s] underlying message was unmistakable: Women should consider themselves first a vessel for human life and make decisions about their health and behavior based on that possibility,” Rebecca Ruiz wrote at Mashable, in a typical reaction.

The (completely understandable) outrage at the CDC’s tone-deaf and condescending messaging has, unfortunately, drowned out information on the key question for many pregnant women: Is any amount of alcohol during pregnancy okay? And are there times when it should be absolutely avoided?

We all know that heavy drinking and binge drinking are harmful during pregnancy. Fetal alcohol syndrome, caused by heavy drinking during pregnancy, affects an estimated 2 to 7 children out of 1000. Another 2 to 7% of U.S. children are thought to suffer milder forms of cognitive impairment due to alcohol exposure in the womb.

But what about light drinking, a champagne toast or an occasional glass of wine at dinner? Women–pregnant, pre-pregnant, and otherwise–receive conflicting advice about the safety of light drinking.

Economist Emily Oster, in her bestselling pregnancy advice book Expecting Better, says pregnant women can be comfortable with “1 to 2 drinks a week in the first trimester” and one drink daily afterward, a stance she continues to stand behind.

Many doctors also greenlight the occasional drink, as Ruth Graham of Slate notes: “Many doctors seem perfectly comfortable with moderate alcohol consumption in the late stages of pregnancy. When I told my doctor that I was enjoying a glass of wine per week in my third trimester, she didn’t bat an eye.”

The CDC, on the other hand, maintains that no amount of drinking is safe.

“Any drinking is going to put your child at risk,” according to Clark Denny, a CDC epidemiologist. “You should not drink if you are pregnant, are considering getting pregnant or even if you could possibly get pregnant.”

Other countries, like the U.K. and France, that once gave less stringent advice–pregnant women should not exceed 1-2 drinks per week–now state no amount of drinking is safe, and that women who are pregnant or trying to conceive should abstain entirely.

At the heart of this debate is the research itself. So, what do we actually know about light drinking during pregnancy?

Let’s start with alcohol and the risk of miscarriage.

  1. Light drinking, the equivalent of 1-2 drinks per week, during the first trimester, boosts the odds of a first trimester miscarriage by about 30%, and the odds of a early second trimester miscarriage (between 13-16 weeks) by about 70%, according to a large study of over 90,000 pregnancies in Denmark. The risk rose with greater intakes. Drinking 4 or more drinks per week during the first trimester more than doubled the odds of a miscarriage. A U.S. based study found that women who drink 2 times per week in their first trimesters had a 25% chance of miscarriage, compared to a 14% chance for those who abstained. Other studies also find a higher risk of miscarriage for light drinkers (see here and here).

Does this mean that light drinking early in pregnancy causes miscarriage? Unfortunately, we cannot say for sure. Experimental studies in humans are impossible, so there are a lot of unknowns.

For one, some women may understate how much they actually drank during pregnancy, so the apparent rise in miscarriage could actually stem from moderate to heavy, rather than light, drinking.

Women who drink heavily during pregnancy often also smoke or have partners who smoke, and are more likely use drugs, receive worse prenatal care, live in poverty and experience extreme chronic stress–all of which can raise the risk of miscarriage and cognitive problems in their children, and any and all of these factors could exacerbate the toxic effects of alcohol on the fetus.

Poor nutrition and smoking seem to worsen the effects of alcohol. This makes sense, as alcohol lowers how much nourishment reaches the fetus.

Women who drink alcohol during their first trimester may have less nausea. (I for one could not get near alcohol in my first trimester, as much as I might, after a long day of nausea and chasing after a toddler, desire a drink.) Although about 25% of women do not experience nausea during pregnancy, an absence of nausea is linked with an increased risk of miscarriage, probably because poorly developing pregnancies produce fewer symptoms.

And finally, the problem may not arise from drinking during early pregnancy but from drinking before pregnancy.

2. Drinking alcohol may lower the chances of pregnancy, and increase the chances of miscarriage, by causing chromosomal abnormalities in the egg before ovulation. Alcohol has been shown to impair meiosis, the critical two-step cell division in maturing egg follicles, leading to chromosomally abnormal eggs. Chromosomal abnormalities account for over half of first trimester miscarriages. Worse, because eggs take several months to fully mature, even drinking in the months before conception could be harmful.

How much alcohol do you have to drink to harm your eggs? Again, we don’t have a good answer. The degree of harm likely depends on a lot of other things, like your age, your overall fecundity, your alcohol tolerance, how much alcohol you drink, and when you drink relative to critical phases in the egg’s development.

Clearly, even formerly heavy drinkers go on to have chromosomally normal and perfectly healthy pregnancies, so the effect is not absolute. The increase in chromosomal abnormalities is probably most problematic for couples already suffering from fertility issues. Among couples undergoing IVF, for instance, drinking appears to lower their chances of pregnancy.

Because the human data are limited, we have to turn to animal models. In one study using monkeys, the equivalent of binge drinking (4-5 drinks at a sitting) twice a week lowered the number of chromosomally normal eggs and increased the chances of miscarriage.

3. Alcohol does not reach the developing embryo until the 3rd week after fertilization, or pregnancy week 4, right after most pregnancy tests turn positive. In other words, even if you got pregnant on your honeymoon while more than a little tipsy and drank cocktails on the beach for the rest of the week, you have nothing to worry about. That alcohol did not reach your embryo.

What about harm to the fetus’s developing brain? Here’s the problem: No one knows at what threshold drinking alcohol becomes harmful, and that threshold may vary from person to person, just like alcohol tolerance and metabolism varies from person to person.

Heavy drinking and frequent binge drinking are clearly bad, but what about that occasional glass of wine or cocktail?

Emily Oster finds the not one drop rule propounded by the CDC and others absurd, and it’s easy to see where she is coming from. Lots of chemicals known to be harmful in large quantities are completely safe in small amounts. As she puts it,

“If you have too many bananas (and I mean a LOT of bananas), the excess of potassium can be a real problem, but no doctor is going around saying “No amount of bananas have been proven safe!” He’d be laughed out of a medical conference.”

But this argument, a version of the Paracelsus principle–the dose makes the poison–depends on the poison in question. Some toxins, like lead, are unsafe at any amount.

We don’t have great information about the actual threshold at which alcohol causes harm, or when harm is most likely to occur. But let’s sift through what we do know.

4. By the third week after conception (the 5th week of pregnancy), alcohol and its byproducts cross the placenta. Based on animal research, the fetus is believed to experience the same blood alcohol level as its mother.

5. Alcohol is a known neurotoxin. Although how alcohol causes damage is not entirely clear, neuronal loss with heavy or binge drinking is evident in animals and in humans. Harmful effects may be especially pronounced in the developing brain, particularly during the first trimester, when many of the changes in facial morphology in FAS appear to originate. Damage to slow growing brain structures, like the cerebellum, likely occurs throughout pregnancy.

6. Large epidemiological studies find no evidence of cognitive impairment with light drinking (1-2 drinks per week) in the second and third trimesters and less than a drink a week, on average, in the first trimester. This research is the basis of Emily Oster’s claim that a drink a day in the second and third trimesters is okay.

One of the largest of these studies is the U.K. Millennium cohort, which has followed a nationally representative sample of 11,000 children born betwen 2000-2002. At age 3, age 5, and age 7, both boys and girls whose mothers drank about 1-2 drinks per week actually had better overall cognitive performance and fewer behavioral and attention problems than children whose mothers abstained from drinking during pregnancy. Heavier drinking, on the other hand, was associated with worse cognitive performance and more behavioral problems.

(The higher test scores among children of light drinkers was almost surely NOT because alcohol benefited their development, but because women who drank lightly were on average more educated and of a higher socioeconomic status than women who abstained. This confounding of light drinking with education and socioeconomic status is actually a huge problem for interpreting this study’s results. Parental education, income, and social class all predict better cognitive performance and fewer behavior problems. So, who is to say that these children would not have been more advantaged had their mothers abstained throughout pregnancy?)

Other studies have found no effect on test scores or mental health at age 11 among children of mothers who drank less than 1 glass per week during their first trimester; no increase in mental health or behavior problems among children of light drinkers at age 2, 5, and 8 (but worse mental health seen among moderate, binge, and heavy drinkers); and no impairment in cognition, learning, or attention among 14 year olds whose mothers drank an average of less than a glass a day early or late in pregnancy; and no reduction in IQ, attention, or executive function at age 5 in women who drank up to an average of 5 drinks per week.

In short, light drinking during pregnancy, less than a drink a day on average, and no more than 1 drink at a sitting, has not been shown to cause detectable harm.

Because light drinking is more common among highly educated, high income women, the advantages of which could mask any subtle impairments caused by small doses of alcohol, we need to take these findings with a grain of salt.

7. Individuals in how quickly they metabolize alcohol and its byproducts. These differences probably influence the threshold at which alcohol causes harm to a fetus. Even among those who drink heavily during pregnancy, only about 5%  will give birth to a baby with Fetal Alcohol Syndrome. 

A recent study looking at IQ at age 8 found similar results for moderate drinkers. Among  slow alcohol metabolizers, moderate drinking (1-6 drinks/week) was linked with lower IQ. No link was found for fast metabolizers, or among poor metabolizers who abstained from alcohol.

The Bottom Line

Drinking more than 2 drinks a week in the first trimester appears to substantially increase the risk of miscarriage. That said, we do not know whether alcohol causes miscarriage. A lack of nausea, or other problems that often go hand in hand with drinking, like smoking, may contribute to this effect.

Alcohol causing miscarriage, however, is biologically plausible. Alcohol can cause chromosomal abnormalities in the egg prior to conception. This does not happen all the time. We all know that alcohol use before conception can lead to perfectly healthy pregnancies. Still, couples who are struggling to conceive may boost their chances by abstaining from alcohol.

What about children’s cognitive abilities and emotional and mental health? Here, very light drinking, less than a drink per week on average, has not been not been shown to be harmful. And many studies find no harmful effects of 1-2 drinks per week.

However, women vary considerably in their ability to metabolize alcohol, based on their body size, liver size, and genetics. Other factors, like whether you drink with food and how quickly you drink (no tequila shots, please!), also affect the amount of alcohol reaching the fetus. These facts make setting a “safe” threshold is impossible.

Given this variability, here’s my personal take: It seems wise to largely avoid alcohol during pregnancy, especially during the first trimester. An occasional glass of wine drunk slowly with dinner is probably fine, but I personally don’t see the upside to pushing the limits.

At the same time, women who drink a glass of wine here and there have no cause for alarm. The CDC’s draconian, not-one-drop stance is probably based on a slippery slope argument. They worry that if they say an occasional glass of wine or beer is fine, women will read their recommendation as license to overindulge.

On the other hand, Emily Oster’s advice to drink “up to 1 drink a day in the second and third trimesters, and 1 to 2 drinks a week in the first trimester” feels too risky for my blood. Most studies define light drinking as 1-2 drinks per week, much lower than Oster’s recommended maximum for the second and third trimesters.

At the end of the day, every woman is going to weigh the risks and benefits of light drinking a little differently. A reasonable woman could see the available evidence and feel comfortable with 1 to 2 drinks a week; another reasonable woman could see the available evidence and decide to abstain entirely.

Curious about drinking after pregnancy? Check out my post on drinking while breastfeeding.

Back Sleeping During Pregnancy and the Sydney Stillbirth Study

Pregnancy can be cruel. Just when you are at your most swollen, bloated, and exhausted, sleep proves frustratingly elusive. Every night, you toss and turn, trying to find a comfortable position, your back aching, and your belly pressing down on your bladder. And then, as you finally start to drift off, you realize you need to pee.

To make matters worse, despite having an enormous bowling ball attached to your stomach, you are told you cannot sleep on your back:

“After 16 weeks of pregnancy, experts advise women to not sleep on their backs, but rather should lie on their sides, ideally the left side” states a popular pregnancy blog.

But who came up with this idea?

This advice stems three studies that have linked back sleeping with late stillbirth (pregnancy loss after 28 weeks). (Interestingly these warnings predated the three studies, so they are not exactly the reason women are told to avoid back sleeping)

I described the first two studies, one conducted in Ghana, the other in New Zealand, in an earlier post, and concluded that not only did they provide no reason for alarm, they certainly do not justify blanket advice again back sleeping.

In 2015, a third study came out linking back sleeping with late stillbirth. Does it change the overall picture?

Continue reading “Back Sleeping During Pregnancy and the Sydney Stillbirth Study”

Vitamin D in Breastmilk and My Daughter’s Diagnosis with Type 1 Diabetes

IMG_2385
Sydney, catching bubbles at her birthday party this month.

A few weeks ago, I was all set to write about the vitamin D needs of pregnant and nursing women. Increased sunscreen use and less time spent outdoors means that few women can meet their vitamin D needs through sunlight exposure alone. As a result, many pregnant women are insufficient in the vitamin.

The medical community is clearly concerned about women’s low levels of vitamin D: The American Pregnancy Association recently raised their recommended vitamin D intake for pregnant and nursing women from 400 IU to 4000 IU, a tenfold increase. The change was precipitated by a recent randomized control trial, in which supplementation with 4,000 IUs a day was shown to be safe and highly effective at reducing vitamin D deficiency among pregnant women.

I only wish these changes had come sooner.

I say this because last weekend, my daughter Sydney, who turned two this month, was diagnosed with Type 1 Diabetes–a disease that may be staved off, in part, by high levels of vitamin D during infancy.

Continue reading “Vitamin D in Breastmilk and My Daughter’s Diagnosis with Type 1 Diabetes”

The Fetal “Gender Nub”: How To Learn Your Baby’s Gender at the First Trimester Screening

Kudos to people who can wait until the birth to find out if they are having a boy or girl. The feminist in me feels guilty about this, but I never wanted to wait that long. Pretty much the second I learned I was pregnant, I started trying to figure out if it was a boy or or girl.

The good news for people like me: ultrasounds can now detect a baby’s gender as early as 12-13 weeks gestation.

Genetic testing through CVS remains the most accurate way to determine fetal sex in the first trimester. But since this test carries a slight risk of miscarriage, many of us choose not to have it performed. (New blood-based tests that rely on cell free DNA can detect your baby’s gender as early as 9 weeks, without increasing the risk of miscarriage, but these are only about 95% accurate in the first trimester).

Until recently, forging genetic testing meant we had to wait until the second trimester screening to learn our baby genders, sometime around 18 to 20 weeks gestation. By that time, the penis, testes, and labial folds are clearly visible on an ultrasound.

The latest research, however, suggests we can learn the gender months earlier, during the ultrasound for the first trimester screen, which is performed sometime between 11 weeks 0 days to 13 weeks 6 days of gestation. The key is scheduling your scan towards the end that window.

Male and female fetuses look pretty similar throughout most of the first trimester. The genitalia are just starting to develop from their root, the “genital tubercle,” which slowly develops into either a penis or clitoris. This genital tubercle is same size in boys and girls until around 14 weeks gestation, when the penis begins to elongate.

A sonographer therefore has to rely on more subtle clues to determine gender in the first trimester. The angle of the genital tubercle is one important clue. By 12-13 weeks gestation, the angle of the penis begins to point up, towards the baby’s head, while the clitoris remains flat or points slightly down.

The ultrasound images below illustrate this. A male fetus is shown on the left, a female fetus on the right. The angle of the genital tubercle is noted with faint white lines.

Screen Shot 2014-11-07 at 4.06.27 PM
From Efrat et al. 1999

In small study of 172 pregnancies, sonographers  were able to accurately detect fetal gender using this angle from about 12 weeks on. Before then, sonographers correctly identified only 70% of fetuses. They were most prone to misclassify the boys: roughly half of the male fetuses were misclassified as girls. So at 11 weeks, when the sonographers guessed that a fetus was a boy, they were usually correct. But when they guessed it was a girl, they were often wrong.

But by 12 weeks this method’s accuracy shot up to 98%. By 13 weeks, there were no more misidentifications; 100% of their classifications were correct. In a follow-up study of 656 pregnancies, sonographers were again perfectly accurate by 13 weeks.

At this point in pregnancy, using the angle of the genital tubercle is more accurate than trying to detect the labia or testes, the method commonly used to determine gender in the second trimester. Classification by the latter method was only about 75% accurate until 14 weeks.

(Incidentally, several websites, like this post at CafeMom and this one at About Health, claim that fetal gender can be detected with nearly 100% accuracy at the 6-8 week ultrasound using “Ramzi’s Method”. I tracked these claims down. All of them appear to derive a paper written by Dr. Saad Ramzi Ismail, which was posted to obgyn.net last year (and has since been removed). In it, Dr Ismail claims that the placenta is almost always on the left side for girls and on the right side for boys. While her paper is formatted and reads like a legitimate scientific article, it was never published in an actual scientific journal. Moreover, it seems extremely unlikely that, if we could determine gender by something as simple as the location of the placenta, we would already know this and use this method all the time. So, as far as I can tell, “Ramzi’s method” is pure junk science.)

The Bottom Line

If you want to learn your baby’s gender, schedule your first trimester scan for 13 weeks gestation. The methods used to detect gender at this fetal age are pretty new, so some sonographers may be hesitant to give your their best guess. But don’t let this deter you. Ask! They are very likely to get it right.

Additional Reading

Like this post? You may also like my take on fetal sex tests based on cell free DNA. With a simple blood draw, these tests can determine fetal sex as early as 9 weeks.

References

Efrat Z. Akinfenwa O.O, and Nicolaides K. H. (1999). First-trimester determination of fetal gender by     ultrasound. Ultrasound Obstet Gynecol 13:305–307.

Efrat Z., Perri T., Ramati E., Tugendreich D., and Meizner I. (2006). Fetal gender assignment by first-trimester ultrasound. Ultrasound Obstet Gynecol.27(6):619-21.

Emerson D.S., Felker R.E., and Brown DL. (1989). The sagittal sign. An early second trimester sonographic indicator of fetal gender. J Ultrasound Med. Jun;8(6):293-7.

Your Due Date Is Wrong–So When Is Labor Most Likely?

Can we please stop with this due date nonsense already?

Yes, the due date is not a precise date, only an estimate. And yes,  most women will deliver within 2 weeks of their so called “due date”.

But the due date has bigger problems.

Pregnant woman marking off dates on the calendar

Actual birth data, from real pregnant women, shows that the due date is not only an imprecise delivery estimate–as any single day would be–it is 1-4 days too early. Statistically-speaking, it is biased. And bias is bad. Continue reading “Your Due Date Is Wrong–So When Is Labor Most Likely?”

It’s (Probably) Safe to Sleep on Your Back While Pregnant

Can you safely sleep on your back while pregnant? Here’s what the latest research has to say.

My third trimester in my second pregnancy was rough. The days were fine, but the nights were awful. I could not fall asleep. I was too uncomfortable. And as a second time mom, I was desperate. Months of sleep deprivation were my certain future. Pregnancy was supposed to be an opportunity to stock up on sleep before the newborn period.

The only remotely comfortable position was lying on my back, propped up with a couple of pillows. But several pregnancy websites and and my OBs had warned me against sleeping on my back during pregnancy.

More than anything, I wanted to disregard this advice. But I needed to know how big a risk, if any, I would be taking by sleeping on my back.

My OBs were not helpful in this regard. Within the same clinic, one OB told me to avoid lying on my back from 4 months on, another told me to avoid this position from 7 months on, and a third said not to worry until the last month of pregnancy. When asked, none of them could tell me the magnitude of the risk.

Eventually, I dug into the research myself. Once I did, I understood why the advice is confusing to mothers: the underlying research is a mess.

The rationale for this prohibition is simple enough: lying on one’s back can cause supine hypotensive syndrome, sometimes known as aortocaval compression syndrome.

A pregnant woman woman’s belly can compress the inferior vena cava, a large vein running under the right side of her uterus; and compression of the inferior vena cava can cause a drop in blood pressure. In rare cases, the drop in blood pressure is severe enough to reduce heart output, lower oxygen going to the brain, and cause fainting.

Although the drop in blood pressure is unlikely to harm the mother, the concern is that if a pregnant woman’s oxygen levels drop, her baby’s might too. Under normal circumstances, though, women typically become uncomfortable and change their position before their blood pressure takes a serious dip.

lateral versus supine

Supine hypotensive syndrome has been reported as early as the second trimester, but it is mainly a problem of late pregnancy, after 36 weeks or so.

Despite how scary this sounds (“I might be depriving my baby of oxygen without knowing it”), according to a recent research review, back sleeping is safe for the vast majority of pregnant women. The reviewers build a compelling case: First, only very small percentage of pregnant women experience low blood pressure when lying on their back. Even among those women, the changes in their blood pressure do not appear to affect the fetus. Studies have found no effects on fetal blood flow or on fetal well-being during non-stress tests.

Second, the symptoms of low blood pressure (dizziness, nausea, a rapid heartbeat) are easily recognizable. Women can figure out for themselves if lying on their back makes them uncomfortable, and avoid the practice if it does. In the reviewers words:

Advising women to sleep or lie exclusively on the left side is not practical and is irrelevant to the vast majority of patients. Instead, women should be told that a small minority of pregnant women feel faint when lying flat. Women can easily determine whether lying flat has this effect on them, and most will adopt a comfortable position that is likely to be a left supine position or variant thereof.

Third, previous research did not examine back sleeping. The research only addressed positioning women during surgery, when they are completely immobilized and unable to change their position.

This review was written in 2007. Its conclusions are clear and reassuring. Unfortunately, since its publication, two more recent studies muddy these waters a bit.

The first study was conducted at a maternity ward in Ghana. Two hundred twenty women who had recently given birth reported their sleep practices during pregnancy. Compared to women who slept in another position, the 21 women who reported either sleeping on their backs or “backs and sides”, had higher rates of NICU admissions (36.8% vs 15.2%) and stillbirths (15.8% vs 3.0%), and were more likely to have given birth to an underweight baby (36.8% vs 10.7%). Even when the researchers controlled for the mother’s age, number of children, gestational age, and pre-eclampsia, these differences remained statistically significant.

The second study was conducted in New Zealand. Researchers interviewed 155 women who experienced unexplained late stillbirths (after 28 weeks) about their sleep position both before pregnancy and in the last month, the last week, and the last night before their pregnancy ended. Their responses were compared to 301 control women, who were a similar number of weeks along but with ongoing pregnancies.

The researchers carefully controlled for several known risk factors for stillbirth: obesity, smoking, low socioeconomic status, maternal age, and number of prior children. Even so, sleeping on one’s back the night before corresponded to a higher risk of a late stillbirth compared to sleeping on one’s left side.

In fact, sleeping on one’s right side or in any other position than on the left side correlated with a higher risk of stillbirth.

Considered together, these two studies seem reason for caution, but not fear. They have a number of problems. Both were quite small, and both relied on women’s ability to recall what positions they slept in. And for the Ghana study, it’s unclear how the findings translate to women in a high income country.

Even assuming these findings hold up, the absolute risk appears to be very, very low. In the New Zealand Study, during its 3-year study period, the rate of late stillbirth was 3.09/1000. The researchers estimate that left side sleeping would lower the risk to 1.93/1000, whereas right side or back sleeping would raise it to 3.93/1000.

To put this risk further in perspective, the New Zealand study also found that going to the bathroom an average of once a night or less (as opposed to two or more times) was associated with an increased risk of a stillbirth. This magnitude of the increase was comparable to back sleeping. Yet, based on these data, no one has proposed that pregnant women should wake up more often to go to the bathroom.

So, what are we to make of these data? In my personal opinion, the research is not strong enough to support blanket warnings against back sleeping. Yes, there is a plausible mechanism for back sleeping causing problems. But the bulk of the evidence suggests that compression of the vena cava very rarely causes problems.

Depending on her risk tolerance and ability to sleep, one woman might look at these data and feel fine sleeping on her back. Another might choose to sleep exclusively on her left side. Both seem like reasonable decisions.

For me, sleeping with a pregnancy pillow, resting mostly but not completely on my back was the right choice. In part, this was because I wanted to be conservative: A tilt of 10 degrees (which you can obtain by propping up your right side with a pregnancy pillow or a regular pillow) has been shown to reduce the risk of low blood pressure.

For me, sleeping in with my right side slightly propped up felt pretty safe. But mostly, it felt comfortable.

Did you avoid lying on or sleeping on your back during pregnancy?

Weight Gain in the Second Trimester: A Sudden Bump Up Is Common — And No Reason to Panic

Weight gain during pregnancy is not steady. Most women gain the most weight in their second trimesters, and much of this weight is water.

24 weeks into my first pregnancy, I was feeling smug. I had been eating right, continuing to exercise, and the last dregs of first trimester nausea and fatigue had faded. I was feeling good.

That is, until my OB took me down a few notches at my 6 month appointment.

She told me I had gained “too much weight”. She passed the chart. It was all there in black and white.

Although I had been on target to gain the “correct” amount of weight by the end of my pregnancy, I had gained a whopping 8 lbs in a month. I was now on a trajectory to gain over the upper limit of 35 pounds. She began what was clearly her set lecture. “Eat less bread. Eat only half of the sandwich…”

But as she spoke, my mind began to wander. I was pretty taken aback. I silently reviewed my recent eating habits. No, I did not think they had changed. Certainly not enough to cause a gain of 8 lbs in a month. And yes, I had been exercising my normal amount. If anything, I had become more active in my second trimester. My energy levels had gone up in the last couple of months, not down.

Convinced that I had done nothing dramatically different in the last month, I started to wonder whether we could accurately or reasonably expect a steady rate of weight gain. Maybe it’s normal to gain a lot of weight in the middle of pregnancy, and less towards the end. Maybe pregnancy weight gain looks more like a curve than a line. Continue reading “Weight Gain in the Second Trimester: A Sudden Bump Up Is Common — And No Reason to Panic”