Opinion

Booze is better than you think, exercise does nothing & other surprising pregnancy finds

Beware! Gardening is a surprisingly dangerous activity for pregnant women due to parasites in the soil.

Expecting Better

Why the Conventional

Pregnancy Wisdom is
Wrong — and What You
Really Need to Know

by Emily Oster

The Penguin Press

The pregnancy experience can be distilled down to one word: Don’t.

Certain foods are off-limits (no raw fish!). Vices are discarded (no caffeine!). Vanity must be abandoned (no dyeing grays!).

It seems that everyone — doctors, yoga teachers, mothers-in-law and checkout ladies at grocery stores — are members of the pregnancy police. Everyone has an opinion.

But not everyone is Emily Oster, a Harvard-trained economics professor at the University of Chicago who lives with an economist husband and their daughter, Penelope. (Oster’s parents are economists, as well.)

When she became pregnant in 2009, Oster found the business of birthing woefully lacking in evidence-based reasoning.

“I asked my doctor about drinking. She said that one or two drinks a week was ‘probably fine.’ ‘Probably fine’ is not a number,” she writes. “The books were the same way. They didn’t always say the same thing, or agree with my doctor, but tended to provide vague reassurances (‘prenatal testing is very safe’) or blanket bans (‘no amount of alcohol has been proven safe’). Again, not numbers.”

When questioning how much of her beloved coffee she could drink a day, she hit the original research papers and drew her own conclusions, following them through her own pregnancy.

All the established guidelines are often “arbitrary,” she discovered. Many habits on the banned list — drinking alcohol in moderation, more coffee than you’d think, using hair dye — haven’t been proven to be harmful, while secret dangers like gardening (!) go underexplored.

To help the many women who reached out to Oster for advice, she compiled her conclusions in her new book, “Expecting Better,” which she describes as a kind of pregnancy “by the numbers.”

“Actually getting the numbers led me to a more relaxed place — a glass of wine every now and then, plenty of coffee, exercise if you want, or not,” she writes. “Economics may not be known as a great stress reliever, but in this case it really is.”

Initially, coffee was the great motivator in Oster’s research.

An ardent coffee fan since her teens, Oster was a four-cup-a-day drinker. When she found out she was pregnant, she wondered how much was really allowed.

Her obstetrician told her to have no more than two cups a day. Another pregnant friend consulted her doctor, who told her not to have any caffeine.

Which was it?

Oster found that both doctors were wrong.

The research shows that high doses of caffeine have been known to cause miscarriages in rodents — but require the human-equivalent of 60 cups of coffee to have such an effect.

A more relevant human study showed that women who drank over two cups of coffee a day actually had lower rates of miscarriage than those who consumed none (not lower enough to be statistically relevant, so if you’re not a coffee drinker and you’re pregnant, don’t go out and buy a triple espresso because of this study).

Oster ultimately concludes that “all evidence supports having up to two cups of coffee” and “much of the evidence supports having three to four cups.”

The same flawed reasoning applies to the ban on hair dye, she writes. Though rat and mouse models reveal that toxic chemicals in hair dye can increase birth defects and cancer, human studies have not shown a similar association.

By all means, get rid of those grays, she writes. Even the American Congress of Obstetricians and Gynecologists suggests that it’s fine after the first trimester.

It’s nice to know that coffee and hair dye are OK during pregnancy — but we bet moms-to-be really want to know: to drink or not to drink?

Though heavy drinking has a clear link to birth defects, low birth weight and other problems, the role of moderate drinking is not as well known.

That’s a shame, because the evidence point to the old maxim: everything in moderation.

Oster’s studies found that there is no evidence that moderate drinking has an impact on IQ, behavioral problems or any cognitive deficits in children.

But it’s important to define moderate drinking. One drink is 4 ounces of wine — not, as Oster puts it, a yard-long margarita.

In addition, speed is important. Binge-drinking exposes the fetus to toxins, while slow, moderate drinking does not, she writes.

Oster concludes that “up to one drink per day in the second and third trimesters and one to two drinks a week in the first trimester” are perfectly fine.

In fact, a recent UK study confirmed Oster’s conclusions. In it, 7,000 10-year-olds were asked to perform balancing tests, while their mothers were quizzed about their alcohol consumption while pregnant.

The study concluded that “low to moderate alcohol consumption did not seem to interfere with a child’s ability to balance.”

So, with all this evidence, why does the stigma remain, and why are the official guidelines to abstain completely from alcohol?

As Jezebel blogger Margaret Hartmann wrote in 2010, “American hysteria over drinking is based less on fact and more on the idea that women can’t be trusted to make decisions about their heath or drink responsibly.”

Oster agrees, adding, “I’m not crazy about the implication that pregnant women are incapable of deciding for themselves — that you have to manipulate our beliefs so we do the right thing. That feels, again, like pregnant women are not given any more credit than children would be in making important decisions.”

So while many pregnant women were paranoid about alcohol — at one point, it was even suggested that expectant mothers should avoid alcohol-based mouthwash — some hidden culprits have been overlooked.

Though Oster cuts down the list of banned foods — she indulged in sushi while pregnant, concluding that the bacteria in sushi “are no worse when you are pregnant than when you are not” — she includes some foods that might not be on every pregnant woman’s radar.

She avoided rare meat because of the risk of toxoplasmosis. She cut out all turkey deli meats for possibly carrying listeria, a bacteria that can cause serious infection in pregnant women. (Some women choose to cut out all deli meats, but Oster believes this is unnecessary.)

Mercury levels in fish are a serious threat, she found. Studies have shown that children born to women with high-mercury exposure levels had a 3.5 IQ-point drop compared to those who had normal levels of exposure. That’s not to say that all fish should be avoided, she adds. Omega-3s have been shown to have a significantly positive impact on brain development.

In the book, she creates a matrix comparing mercury levels to omega-3s and shows that salmon, herring, and sardines should be eaten often, while high-mercury fish like orange roughy, king mackerel, canned tuna and grouper should be avoided.

Another surprise? Gardening could endanger your baby’s development.

Like turkey deli meat and rare poultry, gardening also raises the risk of toxoplasmosis. One European study even found a “strong association” between toxoplasmosis and working with soil. If you must garden, writes Oster, make sure to use gloves and even a mask to avoid inhaling particles.

Even something considered great for you can have serious downsides. Though prenatal yoga has been linked to lower discomfort in the last few weeks of pregnancy and lower levels of pain during labor, hot yoga is actually a real stressor. Anything that increases the body’s temperature to above 101 degrees — like baths, fevers and hot tubs — has been linked to birth defects.

In addition, strenuous exercise should be avoided. In fact, exercise in general doesn’t seem to have much impact on fetal development, preterm birth or rate of C-section. Conversely, those who engage in extreme workouts, ones that bring the heart rate to 90% of its maximum, have been shown to restrict blood flow to their fetuses.

What’s more, those who work out while pregnant only gain 1.3 pounds less than their sedentary counterparts. In short, “There is not a lot of reason to start exercising,” Oster writes.

Oster does stress, however, that pregnancy is not a one-size-fits-all experience.

“In some cases, the existing rule is wrong. In others, it isn’t a question of right or wrong but what is right for you and your pregnancy,” she writes. “I felt fine eating deli meats; my college roommate Tricia looked at all the evidence and decided she would avoid them. All of these are good decisions.”