Strength Training During Pregnancy: What Federal Guidance Says

For healthy pregnancies without medical reasons to avoid it, the federal Physical Activity Guidelines for Americans say a woman can begin or continue light- to moderate-intensity muscle-strengthening activity. The Office on Women's Health (OWH) agrees, with a doctor's okay. Both are part of the U.S. Department of Health and Human Services. Every pregnancy is different, and the guidance itself starts with your health care provider.

1. Start with your provider

The Guidelines say women who are pregnant should be under the care of a health care provider who can monitor the pregnancy, and can discuss whether or how to adjust physical activity during pregnancy and after the baby is born.

OWH adds that this applies to everyone: getting a doctor's or midwife's advice before starting a fitness routine is important for both inactive women and women who exercised before pregnancy. It also lists conditions in which a doctor will advise not exercising, including risk factors for preterm labor, vaginal bleeding, and premature rupture of membranes.

2. Is strength training allowed?

Yes, for most healthy pregnancies. The Guidelines state that unless there are medical reasons to avoid it, a pregnant woman can begin or continue light- to moderate-intensity aerobic and muscle-strengthening activity. If you are starting during pregnancy, increase the amount gradually over time.

If you were already training hard, the Guidelines say women who habitually did vigorous activity, or a lot of aerobic or muscle-strengthening activity, before pregnancy can continue during pregnancy and after giving birth. They generally do not need to drastically reduce activity, as long as they stay healthy and discuss adjustments with their provider. OWH says the same about lifting weights specifically: if you already lift, you may continue with your doctor's okay.

The aerobic target in the Guidelines is at least 150 minutes of moderate-intensity activity a week, ideally spread through the week.

3. How to judge effort

The Guidelines point out that during pregnancy, perceived exertion is often a better guide than heart rate. On a 0 to 10 scale, where 0 is sitting and 10 is your hardest effort, moderate intensity is about 5 to 6. OWH offers a quick check of its own: you should be able to talk while exercising, and if you can't, you may be overdoing it.

4. Positions and activities to avoid

From the Guidelines and OWH:

• No exercises lying on your back after the first trimester. The Guidelines explain this position can restrict blood flow to the uterus and fetus. Ask your provider which exercises in your routine this affects.
• No contact or collision sports, and nothing with a high risk of falling or abdominal trauma. The Guidelines' examples include soccer, basketball, horseback riding, and downhill skiing. OWH adds kickboxing, ice hockey, and gymnastics, and says not to scuba dive.
• Avoid jerky, bouncing, or high-impact movements. OWH notes that connective tissues stretch more easily during pregnancy, raising the risk of joint injury.
• Watch your balance. OWH notes that as the baby grows, your center of gravity shifts and falls become more likely.
• Skip extreme heat and humidity, and don't exercise at high altitude (more than 6,000 feet), which OWH says can keep the baby from getting enough oxygen.

5. Safe-training habits from OWH

• Start slowly, progress gradually, and cool down slowly.
• Take frequent breaks.
• Drink plenty of fluids before, during, and after exercise.
• If you feel uncomfortable, short of breath, or tired, take a break, and go easier next time.

6. Warning signs: stop and call

OWH lists symptoms that mean you should stop exercising and call your doctor as soon as possible:

• Dizziness
• Headache
• Chest pain
• Calf pain or swelling
• Abdominal pain
• Blurred vision
• Fluid leaking from the vagina
• Vaginal bleeding
• Less fetal movement
• Contractions

7. Why it is worth doing

The Guidelines describe the benefits of moderate activity in healthy pregnancies: it increases or maintains cardiorespiratory fitness, reduces the risk of excessive weight gain and gestational diabetes, and reduces symptoms of postpartum depression. They add that the risks are very low and that moderate activity does not increase the risk of low birth weight, preterm delivery, or early pregnancy loss.

OWH also recommends pelvic floor (Kegel) exercises: tighten the pelvic floor muscles for a count of three, relax for three, and repeat 10 to 15 times, three times a day.

8. Key takeaways

• Check with your doctor or midwife first, whether you are new to exercise or already active.
• Without medical reasons to avoid it, light- to moderate-intensity strength training is supported during pregnancy.
• If you lifted before pregnancy, you can usually continue with your provider's okay.
• Aim for an effort of 5 to 6 out of 10 and stay able to talk; avoid lying on your back after the first trimester.
• Stop and call your doctor for dizziness, chest pain, bleeding, fluid leakage, contractions, or less fetal movement.

This article is general information, not medical advice. Talk with a doctor or physical therapist before starting a new exercise routine, especially if you have a health condition or injury.