

This article is an excerpt from the Shortform summary of "Expecting Better" by Emily Oster. Shortform has the world's best summaries of books you should be reading.
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This article is an excerpt from the Shortform summary of "Expecting Better" by Emily Oster. Shortform has the world's best summaries of books you should be reading.
Like this article? Sign up for a free trial here.
Just as common as prescriptions on diet during pregnancy are precautions about activities like gardening and hot tubs. Do you really need to avoid cats? How about avoiding having sex?
Here’s a run-down of common activities commonly barred during pregnancy.
Cats present a risk for toxoplasmosis only during the cat’s first exposure. Therefore, older cats that have already had it, cats don’t eat raw meat, and cats that don’t hunt outside are less likely to have toxoplasmosis. If the cat has kittens when you’re pregnant, risk increases.
There is a strong association between working with soil and toxoplasmosis. So if you garden, wear gloves and maybe a mask.
The misconception around hair dye causing birth defects likely began with experiments that dosed animals at unnaturally high amounts. In humans, a study of hairdressers found a small but significant increase in low-birth-weight babies, but this was not replicated and may be due to other things (like standing a lot).
Hair dye is likely safe, particularly after the first trimester.
Raising your body temperature above 101 degrees in the first trimester increases risk of gastroschisis and anencephaly, a neural tube defect.
Hot tubs and Bikram Yoga are around 105 degrees, as are very hot days, so avoid these in the first trimester. After the neural tube forms in first trimester, it may be safer.
A Spanish study did find that very hot days seemed to induce labor earlier (by about 5 days). So if you’re near your due date, consider staying inside on hot days.
The baby is protected in a giant cushiony fluid sac, and sex isn’t going to hurt it. Go nuts.
The cervix is more sensitive during pregnancy, so hitting it may induce some bleeding, which is normal.
The recommended limit on radiation exposure for the duration of pregnancy is 1 mSv (millisievert). This is conservative, with experts suggesting there are no definitive data showing fetal harm at doses below 20 mSv. Oster does note that exposure to twice this limit might increase the risk of the child having a fatal cancer by 1 in 5,000.
How does this translate to flying? A single 4-hour flight would deliver at most 0.02 mSv, or 2% of the limit. And flight attendants receive around 1.5 mSv per year, so each individual flight is not a big deal.
How about airport security? A single screening has a maximum of 0.25 μSv, or 0.025% of the limit. In other words, you could get a screening every single day and that would represent 9% of your annual conservative limit.
In other words, unless you’re a flight attendant, you probably won’t reach the conservative limit. But you can always opt for the pat-down instead of the X-ray.
(Shortform note: to put these radiation doses into perspective, here are examples of a range of doses:
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Here's what you'll find in our full Expecting Better summary: