Staying healthy during pregnancy comes down to a handful of core habits: eating well, staying active, getting the right nutrients, and keeping up with prenatal screenings. None of it requires a dramatic lifestyle overhaul, but the specifics matter more than you might expect. Here’s what the evidence says about each one.
Start Folic Acid Early
Folic acid is the single most important supplement to take before and during early pregnancy. Getting 400 micrograms (mcg) daily helps prevent neural tube defects, which are serious birth defects of the brain and spine that develop in the first few weeks after conception, often before you even know you’re pregnant. That’s why the CDC recommends starting folic acid at least one month before conception and continuing through early pregnancy.
If you’ve had a previous pregnancy affected by a neural tube defect, the recommended dose jumps to 4,000 mcg daily, starting one month before conception and continuing through the first trimester. Most prenatal vitamins contain 400 to 800 mcg, so check the label on yours.
What and How Much to Eat
You don’t actually need extra calories during the first trimester. Weight gain is minimal in those early months, and your regular intake is typically sufficient. In the second trimester, you need roughly 340 extra calories per day, and in the third trimester, about 450 extra. That’s less than most people assume: 340 calories is roughly a cup of yogurt with granola and fruit, not a second dinner.
Iron needs increase significantly. The recommended daily allowance during pregnancy is 27 mg, up from 18 mg for non-pregnant women. Iron supports the increased blood volume your body produces to supply oxygen to your baby. Lean red meat, beans, spinach, and fortified cereals are good sources, and your prenatal vitamin likely covers the gap, but iron-rich foods still matter.
Fish is worth eating for its omega-3 fatty acids, but mercury content varies widely by species. The FDA recommends 8 to 12 ounces per week of low-mercury fish (about two to three servings). Salmon, shrimp, tilapia, and cod are all good options. Avoid king mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish, and bigeye tuna entirely, as these carry the highest mercury levels.
Caffeine is a gray area. The long-standing threshold has been 200 milligrams per day (roughly two cups of coffee), but NIH-funded research found that even intake below that level was associated with slightly smaller birth size and reduced lean body mass in newborns. If you can cut back or eliminate caffeine-containing beverages, that’s the more cautious approach.
How Much Weight to Gain
Healthy weight gain during pregnancy depends on your pre-pregnancy BMI. The CDC’s guidelines for a single pregnancy break down like this:
- Underweight (BMI under 18.5): 28 to 40 pounds
- Normal weight (BMI 18.5 to 24.9): 25 to 35 pounds
- Overweight (BMI 25.0 to 29.9): 15 to 25 pounds
- Obese (BMI 30.0 to 39.9): 11 to 20 pounds
For twins, every range shifts higher. A woman with a normal pre-pregnancy BMI carrying twins should expect to gain 37 to 54 pounds. Gaining too little or too much both carry risks: too little is linked to preterm birth and low birth weight, while too much increases the likelihood of gestational diabetes, high blood pressure, and a larger baby that complicates delivery.
Exercise That’s Safe and Beneficial
The American College of Obstetricians and Gynecologists recommends at least 150 minutes of moderate-intensity aerobic activity per week during pregnancy, spread across multiple days rather than crammed into one or two sessions. That’s about 30 minutes on five days, and “moderate intensity” means you can carry on a conversation while doing it.
Activities with strong safety records during pregnancy include walking, stationary cycling, swimming, water aerobics, dancing, resistance training with weights or bands, and stretching. These are not consolation prizes for giving up “real” exercise. Resistance training preserves muscle mass and can reduce back pain. Water-based exercise takes pressure off your joints while providing a solid cardiovascular workout.
What to skip: anything with a high risk of impact or falls. Contact sports, downhill skiing, horseback riding, and activities where you could take a blow to the abdomen are off the table. Avoid exercising to the point of overheating, especially in hot or humid conditions. If you were already active before pregnancy, you can generally continue your routine with modifications. If you were sedentary, starting with short walks and building up gradually is a safe entry point.
Key Prenatal Screenings
Two screenings deserve special attention because the conditions they catch can develop silently.
Gestational Diabetes
Most women are screened between 24 and 28 weeks. The initial test involves drinking a sugary solution and having your blood drawn an hour later. If results are elevated, you’ll do a longer follow-up test that tracks blood sugar over two to three hours. Gestational diabetes often causes no symptoms at all, which is exactly why screening matters. Left unmanaged, it can lead to an unusually large baby, delivery complications, and increased risk of type 2 diabetes later in life for both mother and child.
Preeclampsia
Preeclampsia is a blood pressure condition that typically appears after the 20th week. A reading of 140/90 or higher will prompt further evaluation. But blood pressure isn’t the only signal. Watch for headaches that won’t go away, blurred vision or seeing spots, sudden swelling in your face and hands, pain in your upper right abdomen, and trouble breathing. Swollen feet alone are common in pregnancy and not necessarily a concern. Preeclampsia can escalate quickly, so these symptoms warrant same-day contact with your provider.
Sleep Positions in Later Pregnancy
Once your abdomen starts to expand, sleeping on your left side with your knees bent is the most recommended position. This keeps your growing uterus from pressing on the vena cava, the large vein that returns blood to your heart. When that vein is compressed (which happens when you sleep on your back, especially after 20 weeks), circulation drops to both you and the baby. You may notice dizziness, shortness of breath, or a drop in blood pressure.
Back sleeping also loads weight onto your spine, worsening the lower back pain that already affects most pregnant people. It’s linked to increased snoring and sleep apnea as well. A pillow between your knees or a pregnancy wedge behind your back can help you stay on your side through the night. If you wake up on your back, don’t panic. Just roll to your side and settle back in.
Everyday Habits That Add Up
Hydration is easy to overlook. Your blood volume increases by nearly 50% during pregnancy, and staying well-hydrated supports that expansion, reduces constipation, and helps prevent urinary tract infections. Aim for about 10 cups of fluid per day, more if you’re exercising or it’s hot outside.
Alcohol has no established safe amount during pregnancy. The same applies to smoking and recreational drugs, all of which are linked to preterm birth, low birth weight, and developmental problems. If quitting is difficult, your provider can connect you with support programs that are specifically designed for pregnancy.
Stress management is not just a nice-to-have. Chronic stress raises cortisol levels, which can affect fetal development and increase the risk of preterm delivery. Regular physical activity helps, as does adequate sleep. Even simple practices like a consistent bedtime routine or brief daily walks can lower the baseline stress your body carries.