Data-Driven Pregnancy Do’s and Don’ts

Posted On: September 15, 2021 By Nathan D. Fox, MD

With all the advice freely available online and found in books both old and hot off the press, there’s a plethora of opinions on what expecting mothers should and shouldn’t do during pregnancy. Unfortunately, many of these sources are misleading, and in some cases, plain wrong, leading to people trusting Google over their doctor when they’re wondering if they’re in labor.

Helping to cut through the noise with her personal experience and scientific approach to the cold data about pregnancy care is Dr. Emily Oster, an economist and author of “Expecting Better: Why the Conventional Pregnancy Wisdom Is Wrong–and What You Really Need to Know.”

Why Trust an Economist for Pregnancy Advice?

It’s no secret that Dr. Oster isn’t a medical doctor, yet she’s published multiple books about pregnancy and parenting. Dr. Oster’s interest in life during pregnancy was borne out of a sense of commonality with other new mothers who frantically search any available sources for advice on what’s the safest and healthiest way to navigate this sensitive time of their lives. Disappointed by some of the hardline stances she discovered in her research, Dr. Oster started looking at the original studies, interpreting the data as only a person with a doctoral degree in economics can.

She discovered issues billed as black-and-white that simply didn’t have the evidence to prove they should be treated as such. Small sample sizes, lack of randomized control studies, and other weaknesses led Dr. Oster to a world of gray areas, where a little of this and that in moderation may actually be beneficial, rather than harmful, during pregnancy.

She compiled her research into “Expecting Better,” which was published in 2013 — not without its share of pushback. In talking with Dr. Nathan Fox on our Healthful Woman podcast, Dr. Oster described some of these misconceptions, which Dr. Fox also encounters on a regular basis himself.

Common Misconceptions About Pregnancy

It’s understandable that people have serious, relevant concerns about what they believe is safe for them during pregnancy. As Dr. Oster says, however, “I think it’s helpful for people to understand, ‘why are we concerned about this in the first place?’” Approaching fears of unsafe foods or substances should be contextualized within each individual’s unique concerns or fears, such as about birth defects, high blood pressure, or miscarriage.

That said, there’s a thousand different ways the path of pregnancy can go, and if having strict barriers in place helps you navigate this complex time, then live within those barriers. Those boundaries simply may not need to be there for everyone, based on the medical evidence we have so far.

Dr. Fox and Dr. Oster covered many more topics in their podcast about the misconceptions of pregnancy care, so please check out their podcast to learn more about specific foods and activities if you’re interested.


One of the most deeply set beliefs about what foods are safe during pregnancy lies with the dreaded raw fish found in sushi. People avoid it like the plague when they’re pregnant because of fears about mercury poisoning and salmonella, thinking it could not only affect their health, but dramatically affect their baby as well. However, the reality is far from this widely shared belief.

While mercury contamination is a real threat for pregnant people, it’s all dependent on the type of fish, not whether it’s raw or cooked. Dr. Fox explains that species of fish such as salmon, whitefish, shellfish, and others have little to no mercury, which makes the issue moot. Fish like swordfish, king mackerel, and shark are known to have elevated levels of mercury, so in those cases, it’s recommended to avoid eating these types of fish.

In regard to salmonella, Dr. Oster says that only raw fish would have the potential to cause food poisoning, and even fresh, properly prepared raw fish has very little chance of having salmonella. This doesn’t even just apply to pregnancy, as you should always be careful when eating sushi with raw fish, avoiding it if anything about it looks or smells off.

Deli Meat

Common knowledge has also relegated deli meat to the “no” column over fears of listeria infection. Listeria is a bacteria that has been found in many different types of foods over the years, including hummus, cantaloupes, ice cream, and of course, deli meat.

However, the risk of contracting listeria from deli meat, especially fresh deli meat from the counter, is extremely low. Dr. Fox does say, “all right, maybe don’t eat the stuff that’s packaged and sitting around in the supermarket shelf for six months,” and continued that for people who are truly paranoid can ensure their safety from cold cuts by simply heating it in the microwave before eating it.


It’s known and proven that ingesting large amounts of alcohol during pregnancy leads to both short- and long-term complications in babies. However, there’s also evidence that low amounts of alcohol has no known negative effect on the health outcomes of babies and children up to the age of 15. Still, when making decisions about how much to drink, many professional societies recommend zero intake policies, due to the fact that there is a risk with alcohol consumption, and alcohol provides no medical benefits; therefore, it’s not worth the risk.

When crafting your pregnancy lifestyle, it’s always best to tell your doctor about your expectations in the first, second, and third trimesters. How do you want to live your life? If giving up a single glass of wine on a night out for 9 months or longer is a large inconvenience, it may be okay in the grand scheme of pregnancy.

Personalized Pregnancy Care in New York City

So much about the pregnancy process is unique to each individual, their lifestyles, and their overall health. That’s why there’s no such thing as a perfect pregnancy — everyone’s looks a little different, including what they eat and drink. Our doctors agree on the things that are supported by hard evidence, and can advise you on creating a balanced diet for the things that are more preference-based. To learn more about what you specifically can and can’t do during pregnancy, schedule a consultation with our maternal fetal medicine specialists today by calling our office or contacting us online today.



Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!

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