Behavioral Do’s, Don’ts and Gray Areas
Historically, the guidance on what women should and shouldn’t do during pregnancy has been very conservative and not always evidence-based
This is the thesis of Emily Oster’s excellent book Expecting Better, which I highly recommend, though I capture the major takeaways here
Also remember: a huge recent industry around pregnancy means companies are incentivized to make claims that you need their “pregnancy-safe” workout plan, shampoo, etc… so a little dose of skepticism is warranted
Lots of behaviors fall in a gray area where it’s up to you to weigh the pros and cons based on your situation, preferences, & risk tolerance. Keep in mind:
First trimester is when to be most cautious due to miscarriage risk
Know yourself - if something goes wrong in pregnancy and you are going to blame a gray area behavior, maybe better to avoid altogether. But if it will meaningfully improve your happiness and you can relinquish self-blame, then it’s totally worth it.
Stress/cortisol is not good for your baby, so if a gray area behavior will help you relax, that actually counts for a lot!
Food & Drink
DO:
Varied Diet: Research suggests that a baby’s food preferences are affected by exposure in the womb, so your efforts now might prevent a picky eater later. One heuristic is to try to make your plate as colorful as possible. More nutrition recs here.
High Omega-3 Fish: the best options are high in Omega-3 but low in mercury, including salmon, herring and sardines. Easy vegetarian sources are walnuts, chia/flax (throw into smoothies!)
Extra Calories: Consume 300-350 extra calories in 2nd trimester and 500 extra in 3rd trimester. Gaining too much weight is better than gaining too little. See chart at bottom for weight gain guidance.
Water: Hydrate even more than you did pre-pregnancy, adding two or more cups to your previous intake; around ten 8-ounce cups is a good ballpark; water helps amniotic fluid form
Feel Comfortable Enjoying: despite what you may read elsewhere, these are totally safe:
Light Coffee: Drink 1-2 cups of coffee (or 200 mg total) a day if you’d like. This is my personal favorite way to combat the annoying pregnancy symptom of constipation ;) Bear in mind that Starbucks coffee is extra high caffeine content
Light Alcohol: Enjoy an occasional alcoholic drink, especially after the first trimester. Maybe it’s a special celebration or someone’s opened a really fancy bottle of wine!
Artificial Sweeteners: Aspartame (Equal, Nutrasweet), Splenda, and Stevia are all safe for pregnancy, so drinking Diet Coke/Coke Zero in moderation is fine (just don’t exceed the caffeine amounts above!). Avoid Saccharin though (Sweet N’ Low)
Tempura/Veg Sushi Rolls: since tempura is cooked, there is zero risk!
GRAY AREA:
Raw Shellfish/Raw Sushi: These are usually lumped together, but raw shellfish (oysters/clams) is much riskier than sushi. Raw fish poses a theoretical risk of bacteria like salmonella, but no evidence that this poses extra harm for pregnant women. Use judgment - fresh sushi from a nice restaurant in a coastal city is probably fine, but avoid sushi from a Midwest strip mall.
Non-Turkey Deli Meats: other cold cuts also sometimes have listeria outbreaks but it’s hard to predict (other random foods like enoki mushrooms or cantaloupes do too!); Minimize risk by popping meat in the microwave (warm cuts?), or heating up your whole sandwich (needs to be steaming hot to be effective)
Moderate Coffee: Mixed evidence on risks of drinking 3-4 cups of coffee; impact on sleep might be more of a reason to avoid than the caffeine itself. More than 4 cups could increase miscarriage
Moderate Alcohol: Mixed evidence on risks of regularly drinking 1 alcoholic drink (for instance, most nights per week). Can negatively impact sleep. All about your personal tradeoffs - if a glass of wine relaxes you, and the alternative would be a cigarette, definitely go for the wine!
Kombucha: unpasteurized and thus technically could have bad bacteria (like listeria) in addition to the “good” bacteria, but still extremely unlikely. Probably best to avoid homebrewed kombucha but a big-name brand like GT Kombucha is likely safe (caffeine & alcohol levels are low enough to not be a real concern)
Fluoridated Water: there is some evidence to suggest that maternal exposure to fluoride from tap water is associated with a slight decrease in IQ (~3-5 points), particularly in boys. Look up whether your county fluoridates its water and consider drinking bottled water or installing a reverse osmosis filter. More info on this topic here.
DON’T:
Rare Meat and Unwashed Produce: these carry risk of toxoplasmosis which can harm fetus
Queso Fresco and Deli Turkey: these foods account for the largest number of listeria outbreaks
High Mercury Fish: these include big fish like shark, swordfish, grouper, canned tuna. But don’t freak out if you had them once or twice, it’s cumulative exposure that matters
Old Food in the Fridge: Listeria grows best at fridge temperature, so toss anything that’s been languishing too long in your fridge, especially meat
Heavy Alcohol: Heavy drinking (14 or more drinks per week) or binge drinking (4 or more drinks in a single occasion) can cause Fetal Alcohol Syndrome which is serious
Exercise and Leisure
DO:
Stay Active: keep doing whatever exercise you enjoyed pre-pregnancy, as long as it still feels good (otherwise, make modifications). Many women I know jogged or Peloton-ed almost till the end.
Go Swimming: not only is it great, low impact exercise, but once you have a big bump it’ll feel amazing to float
Prenatal-specific exercise: especially in the final trimester, begin “training” for birth and motherhood, by focusing on pelvic floor, squats, strengthening your arms/back for baby-carrying, etc (recs here)
Sex: your closed cervix and amniotic sac protect the baby, so don’t worry about hitting it! It’s possible you’ll have some light bleeding/spotting for a day or two after so don’t freak out (but do contact your OB if it persists or is heavier). Some pregnant women find their sex drive increases during pregnancy while others find it decreases, so just communicate your own needs. As your bump grows, you’ll have to adjust sex positions to remain comfortable.
Air Travel (up to 36 weeks) - the radiation exposure from flying is negligible and poses no risk. The only reason you stop after 36 weeks is in case you go into labor (you don’t want to be in the air or far away from home).
Keep Dying your Hair and Getting Manicures: despite what you may hear, no compelling evidence that it’s risky. I might be more concerned if this is your profession and you’re exposed all day long, but occasional appointments is totally fine.
GRAY AREA:
Ab Exercises: a strong core is helpful for birth and recovery, so definitely keep doing certain exercises like planks and bird dogs. Some people advise against crunches or twists after first trimester, claiming it can lead to diastasis recti (separation of the abs muscles) but no actual evidence for this. Trust your body - if it still feels comfortable, carry on!
Exercise or Sleep on your Back: as your bump grows, it can put pressure on a large vein called the vena cava, which could theoretically restrict blood flow. However, research suggests this may actually be quite uncommon, and another recent study did not find any adverse outcomes from sleeping on the back. By 3rd trimester, you likely won’t feel comfortable on your back anyway given the weight of your bump, but if you want to be extra cautious you could switch to sleeping on your side sooner in 2nd trimester (some say only left side, but either is fine if it feels okay). If you wake up on your back, don’t freak out - just reposition. For exercise, as long as you don’t feel faint, fine to be on your back.
Sunbathing: the biggest risks here are overheating and dehydration, so make sure to be extra aware. Your skin may be increasingly sensitive to burning, so using sunscreen is important especially on your face as sun exposure can exacerbate “chloasma” - the dark spots that commonly appear on your face while pregnant.
Loud Concerts: the worry here is that it could damage baby’s hearing, but as long as you’re not right at the front or near the speakers, it’s probably fine. To be extra safe, you can download a free decibel meter app and try to stay below 115 dBs.
Traveling Locally after 36 Weeks: labor rarely progresses as quickly as you see in the movies, usually a much slower burn; if you have a low-risk pregnancy, as long as you’re within an hour of a reputable hospital, you’re good! Maybe you’d prefer to stay within an hour of your hospital.
Traveling to Areas that had Zika: you’d obviously avoid any area with a current Zika outbreak (thankfully none currently), but some people go further and avoid areas that had Zika cases in the past. You can lower your risk by wearing good mosquito repellent.
Gardening or Caring for a Cat: risk of getting toxoplasmosis, a parasitic infection mainly spread by cat feces. While relatively low risk, it could cause birth defects so wear gloves and wash hands well (or maybe ask your partner to clean the cat litter during your pregnancy).
DON’T:
Push Exercise Too Hard: exerting yourself to the point of breathlessness or above 90% of your maximum heart rate might restrict blood flow to baby. Also, your joints become looser and less stable due to the hormone relaxin (the actual name!), which could increase risk of injury. Recognize that your body is changing, so you should adjust your exercise expectations
Play Risky Sports/Activities: avoid anything where you could fall badly or someone could crash into you. Mountain biking, rock-climbing, horseback riding, skiing, surfing, soccer, hockey
Raise your Body Temp over 100°: especially during first trimester, raised temp could cause birth defects or miscarriage, so avoid hot tubs, saunas, and hot yoga. Use a thermometer for baths to ensure under 100°, and keep hot showers to a reasonable length (showers are safer because water runs down vs. immersing). After first trimester, you could relax these rules as long as under 10 minutes (I’m a fan of dipping in and out of hot tubs, or doing just legs!)
Camp in Deep Wilderness: especially in the final trimester, you’ll want to be able to get to a hospital quickly in case of emergency
Drugs and Medications
Very challenging ethically to study the impact of different medications on pregnant women, so you’ll have to make decisions with limited empirical information. Basically no drugs fall into “Category A” - 100% safe based on controlled studies - not even prenatal vitamins!
The category system (A, B, C, D, X) is being phased out because it was overly simplistic, replaced by a descriptive paragraph about potential risks for more nuance. But since it is often still referenced, I’ll include categories below:
DO:
Prenatal Vitamins: You should take these daily before getting pregnant, throughout pregnancy, and after birth while breastfeeding! More info on picking a pill here.
Discuss Current Meds with OB/Psychiatrist: weigh the risks against the benefits; often, there’s a safer alternative you can switch to
Category B: Animal studies show no risk to fetuses; good evidence of safety in humans, but no controlled studies. Examples include Benadryl, Claritin, Clotrimazole, Metamucil
GRAY AREA:
Category C: Many drugs fall into this category. These have not been studied in humans, but have shown risk to fetuses in animal studies. Or in some cases, no human or animal studies available, so flying a little blind. Potential benefits may still outweigh the risks, especially if used in low doses. Examples include Prozac, Bacitracin, Hydrocortisone, Miralax, Cipro.
Occasional Tylenol (over Advil or Motrin): acetaminophen is def safer than ibuprofen; some doctors now caution against Tylenol as well, but if you really need it, fine to use in low doses
Cannabis: insufficient data but we do know it crosses the placenta. Studies suggest some risks associated with regular cannabis use, but occasional use or CBD-only is less known (though products labeled CBD-only sometimes do contain some THC). If you’re using cannabis for health purposes (sleep, nausea, etc), consider exploring an alternative with better known safety.
DON’T:
Category D: Evidence of risk to human fetus; in some cases, benefit may still outweigh risk, but first explore alternatives. For instance, Xanax, Klonopin and Ativan are Category D, but SSRIs like Lexapro, Zoloft or Prozac (Category C) could be safer alternatives.
Category X: Evidence of risk to human fetus, risks clearly outweigh benefit. Examples include statins and warfarin (blood thinner)
Tobacco/Nicotine: Vaping is less harmful than smoking cigarettes, but still dangerous
Resources
Fact Sheets: check out the “Medications” section; useful for pregnancy and breastfeeding!
OTC Drugs and Psychiatric Drugs: nice summary tables for common issues
