Most pregnancy complications can be significantly reduced through a combination of preconception planning, consistent prenatal care, targeted nutrition, regular physical activity, and knowing which warning signs demand immediate attention. Some steps begin months before conception, while others matter most during specific trimesters. Here’s what actually makes a difference.
Start Before You’re Pregnant
The weeks before conception are more important than most people realize. Begin taking 400 micrograms of folic acid daily, ideally at least a month before trying to conceive. Folic acid prevents neural tube defects of the brain and spine, and by the time a pregnancy test turns positive, the neural tube is already forming. If you’ve had a previous pregnancy affected by a neural tube defect, the recommended dose jumps to 4,000 micrograms daily, starting one month before conception and continuing through the first trimester.
Schedule a preconception visit with your provider to review every medication you take, including over-the-counter drugs and supplements. Some common medications can cause birth defects or need to be swapped for safer alternatives well before pregnancy begins. This is also the time to make sure your vaccinations are current, since several important vaccines (like MMR and varicella) can’t be given during pregnancy but protect against infections that cause serious complications.
If you have a chronic condition like diabetes, asthma, or high blood pressure, work with your provider to get it as well controlled as possible before conceiving. Unmanaged diabetes in early pregnancy, for example, dramatically raises the risk of birth defects and miscarriage. Learn your family health history too. Conditions like preeclampsia, blood clotting disorders, and gestational diabetes often run in families, and knowing your risk profile shapes the monitoring you’ll receive.
Gain the Right Amount of Weight
Weight gain during pregnancy directly affects your risk for gestational diabetes, preeclampsia, and cesarean delivery. The targets depend on your pre-pregnancy BMI:
- Underweight (BMI under 18.5): 28 to 40 pounds
- Normal weight (BMI 18.5 to 24.9): 25 to 35 pounds
- Overweight (BMI 25 to 29.9): 15 to 25 pounds
- Obese (BMI 30 to 39.9): 11 to 20 pounds
For twins, the numbers are substantially higher across every category. Gaining too much weight increases the chance of gestational diabetes, high blood pressure, and a larger baby that complicates delivery. Gaining too little raises the risk of preterm birth and low birth weight. Steady, gradual gain matters more than hitting a number on any given week.
Stay Physically Active
Current guidelines recommend 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. Walking, swimming, stationary cycling, and prenatal yoga all count. Strength training is also encouraged for women with uncomplicated pregnancies.
Exercise during pregnancy reduces the risk of gestational diabetes, preeclampsia, and cesarean birth. The Community Preventive Services Task Force found strong evidence that supervised exercise classes during the first two trimesters are particularly effective at lowering gestational diabetes risk. You don’t need a gym membership to benefit, but structured programs with guidance tend to produce better results than general advice to “stay active.”
Prevent Gestational Diabetes
Gestational diabetes affects roughly 1 in 10 pregnancies and raises the risk of high birth weight, birth injuries, cesarean delivery, and the baby developing metabolic problems later in life. The most effective prevention combines a healthy diet with regular physical activity starting early in pregnancy.
Interventions that work best include some combination of supervised exercise, dietary education, personalized meal plans, food diaries, and individualized support. You don’t need to follow a rigid protocol. The key is eating balanced meals that limit blood sugar spikes (think whole grains, vegetables, lean protein, and healthy fats) while staying consistently active. Screening for gestational diabetes typically happens between 24 and 28 weeks, but your provider may screen earlier if you have risk factors like obesity, a family history of diabetes, or a previous pregnancy with gestational diabetes.
Reduce Your Risk of Preeclampsia
Preeclampsia, a dangerous blood pressure condition that usually develops after 20 weeks, is one of the leading causes of maternal and infant death worldwide. For women at high risk, low-dose aspirin (81 mg per day) started between 12 and 16 weeks of gestation and continued until delivery can meaningfully reduce the chance of developing it.
You’re considered high risk if you have any one of these factors: a history of preeclampsia, carrying multiples, kidney disease, an autoimmune condition, type 1 or type 2 diabetes, or chronic hypertension. You’re also a candidate for aspirin prophylaxis if you have more than one moderate risk factor, which includes first pregnancy, age 35 or older, BMI over 30, family history of preeclampsia, or certain sociodemographic characteristics. This isn’t something to self-prescribe. Your provider will assess your specific risk profile and recommend aspirin if it’s appropriate.
Protect Against Infections
Certain infections during pregnancy can cause miscarriage, preterm birth, birth defects, or serious illness in the newborn. Most are preventable with straightforward hygiene and dietary habits.
Handwashing is the single most effective measure, especially after contact with young children, changing diapers, or handling raw food. Cytomegalovirus (CMV), a common virus that can cause hearing loss and developmental problems in babies, spreads primarily through contact with saliva and urine of toddlers. Avoid sharing food, drinks, or utensils with young children, and wash your hands after wiping their noses or mouths.
To prevent listeriosis, a bacterial infection that can trigger miscarriage or stillbirth:
- Avoid soft cheeses made from unpasteurized milk
- Skip deli meats and lunch meats unless heated to 165°F
- Don’t drink raw milk
- Wash all vegetables thoroughly
Have your partner handle the cat litter. Toxoplasmosis, spread through cat feces, can cause severe brain and eye damage in a developing baby. Also avoid contact with people who are actively sick, especially during flu season or outbreaks of viral illness.
Get Vaccinated During Pregnancy
Three vaccines are routinely recommended during pregnancy, each timed to a specific window:
- Flu shot: Can be given at any point during pregnancy during flu season, but September or October is ideal if you’re in your first or second trimester.
- Tdap (whooping cough): Recommended during each pregnancy, preferably between 27 and 36 weeks. This timing maximizes the antibodies that transfer to your baby, protecting them during the vulnerable first months of life.
- RSV vaccine (Abrysvo): A single dose between 32 and 36 weeks, given between September and January in most of the U.S. This protects infants under 6 months from severe respiratory illness. Only the Pfizer RSV vaccine is approved for use during pregnancy.
Hepatitis B vaccination is also recommended during pregnancy if you haven’t been previously vaccinated. If you’re at risk for hepatitis A, that vaccine can be given during pregnancy as well.
Eliminate Alcohol, Tobacco, and Harmful Exposures
There is no known safe level of alcohol during pregnancy. Drinking can cause a range of birth defects and developmental disabilities collectively known as fetal alcohol spectrum disorders. The safest approach is to stop drinking entirely when trying to conceive.
Smoking during pregnancy increases the risk of preterm birth, low birth weight, placental problems, and stillbirth. If you’re struggling to quit, talk to your provider about cessation support before or as early in pregnancy as possible. Avoid secondhand smoke as well. Steer clear of harmful chemicals, heavy metals, and toxic substances at home and in the workplace. If your job involves chemical exposure, discuss accommodations with your employer and provider early on.
Preventing Preterm Birth
If you’ve had a previous preterm birth, your provider will likely monitor your cervical length with regular ultrasounds during your next pregnancy. The approach to prevention has shifted in recent years. Progesterone supplementation was once widely recommended for anyone with a prior preterm birth, but updated guidance from ACOG now limits its use to women who have both a history of preterm birth and a measurably shortened cervix. Without a shortened cervix, progesterone has not been shown to reduce the risk of recurrence.
For women who do have cervical shortening, your provider will discuss the best approach based on your specific history, cervical measurements, and prior treatments. The options are individualized, and the conversation about what’s right for you should happen early in pregnancy.
Warning Signs That Need Immediate Attention
Even with perfect prevention, complications can still arise. Recognizing urgent warning signs early is one of the most important things you can do to protect yourself. Seek medical care immediately if you experience any of the following during pregnancy or up to six weeks after birth:
- Vision changes: Flashes of light, bright spots, blind spots, temporary loss of vision, blurriness, or double vision.
- Extreme swelling of hands or face: Not the mild puffiness common in late pregnancy, but swelling severe enough that you can’t bend your fingers, wear rings, or fully open your eyes.
- Severe leg or arm swelling, redness, or pain: Especially if it’s on one side only, warm to the touch, or worsens when you flex your foot. This can signal a blood clot.
These symptoms can indicate preeclampsia, blood clots, or other life-threatening conditions. The CDC’s Hear Her campaign emphasizes that pregnant and postpartum women who feel something is wrong should trust that instinct and seek care without delay, even if the symptoms seem vague.