Pregnancy and childbirth is one of the most consequential and stressful things that most women go through.
Given the potential dangers, and the fact that people are committing to 9-months of pregnancy followed by 18 or so years of child rearing, anxiety and caution are understandable.
Understandable caution too often ends up turning into excessive self-denial.
When University of Chicago professor Emily Oster got pregnant, she expected it to be similar to her professional life, a situation where there was good data, plenty of information, and a good basis for herself and her husband (also an economist) to make an informed decision.
She found a massive set of rules, and a lot of studies and doctors mixing up correlation and causation. Her own research, applying the data literate and occasionally sceptical eye of an economist to pregnancy ended up turning into a book, Expecting Better: Why the Conventional Pregnancy Wisdom Is Wrong — and What You Really Need to Know, which is coming out Tuesday.
Here are a few highlights from the book, which is definitely worth picking up for anyone who’s considering or having a child for the expanded data and the coverage of pregnancy from conception to birth.
Alcohol and coffee are fine in moderation
We covered this in more detail in a previous post, but blanket prohibitions on either of the above are misguided. A few cups of coffee a day are fine, Oster finds, and continued her 4 cup a day habit through pregnancy. As much as a glass of wine a day is fine after the first trimester, and a couple a week are fine even then.
Up to two cups are supported as fine by pretty much all evidence, most evidence supports 3 to 4, and even for larger amounts of coffee, the links to miscarriage may be due to the fact that these women were less nauseous, which can indicate other issues.
And as for alcohol, heavy drinking and binge drinking are very much to be avoided. There’s no good evidence that light drinking hurts a baby.
Sushi is fine, and you should eat more, not less fish
The list of prohibited pregnancy foods is vast, and recommendations can be vague and contradictory. Oster took a closer look, and found a few bans don’t hold up to scrutiny.
Do avoid raw/rare meat and poultry, deli turkey (other deli meats are ok), unwashed fruits and vegetables, and queso fresco/raw milk cheeses. The first two put you at risk of toxoplasmosis and the latter two, listeria, both potentially very bad for your baby.
Sushi, though care should be taken to avoid high mercury fish, turns out to be fine. So do raw eggs. They may contain bacteria, but it’s not of a type that’s worse for pregnant women. Just don’t eat suspect discount sushi or a raw eggs from an old carton.
High mercury fish are bad, but many others are not only low in mercury, but high in beneficial omega-3s, which can boost IQ. The effect holds to the point where people that eat tons of fish have smarter kids on average, despite more mercury exposure. Avoiding it all together is a particularly poor outcome.
Skip canned tuna, eat lots of sardines and other little fish.
You can clean a litterbox and dye your hair, but don’t garden
Food bans are only the start. Women are also cautioned against flying, hair dye, hot tubs, gardening, and cleaning a cat’s litter box.
The fears over litter boxes focus on toxoplasmosis, but the likelihood of contracting it that way is quite low, especially if the cat is tested. The risk of contracting it from gardening is quite a bit higher. If you’re working with soil, consider a mask and use gloves.
Unless you’re a hairdresser, or injecting the stuff, hair dye isn’t a concern. You don’t absorb enough when simply colouring your hair.
The “over-35 rule” for invasive testing is a huge oversimplification
The choice about pre-natal testing is one of the most consequential and earliest decisions. Invasive tests, like amniocentesis or CVS carry some risk of miscarriage. Noninvasive screening doesn’t, but is less accurate in measuring the probability of having a chromosomal anomaly like Down’s Syndrome.
Because these issues are more common for older mothers, invasive screening is often only offered to women over 35.
Women under 35 are rarely even offered the choice of invasive screening because of the chances of miscarriage. As Oster puts it, this is “insane.” Every woman or family has different opinions on their ability or desire to raise a child that might have developmental issues, compared to the (very low) prospects of miscarriage and they need to be given the opportunity to make that decision.
The conventional wisdom about weight is wrong
The question of weight gain is particularly stressful, with many doctors giving women a hard time about gaining too much weight. Though the idea that you’re “eating for two” is wrong (you need to eat a bit more, but not a ton more) gaining a bit too much weight isn’t all that big of a deal. Most women manage to take it off.
Targeting some weight then worrying about being a pound or two over isn’t productive. Even 10 or 15 pounds over isn’t really important. If you gain more weight, the baby will be slightly larger on average. If you gain less, the baby could be smaller. Gaining too little weight and having an undersize baby is a larger concern.
“But mostly chill out,” Oster writes.
Exercise doesn’t really matter
Some women are encouraged to exercise, mainly due to concerns about weight. On average, women who exercise during pregnancy don’t end up changing their end weight all that much, and there’s not much evidence that there are other beneficial effects. Basically, most women should just keep doing what they’ve been doing, avoiding over-strenuous exercise or anything that might result in falling.
Bed rest doesn’t prevent premature birth and is bad for you
Preterm birth is fairly common, and can have significant negative impacts. Preterm babies get ill more easily, have lower IQs on average, and occasionally hearing or vision problems, though survival rates are much, much higher than they used to be.
Bed rest is frequently advised for people that could go into preterm labour, but there’s no real evidence that it works.
Not only that, it has negative consequences, including restricting women from working or doing much of anything to help their families, along with potential bone loss, muscle decay, and possibly decreased birth weight.
Doctors know this, but still often prescribe bed rest. The conventional wisdom has hung on, against the evidence.
Find Expecting Better here
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