Exercising Safely During Pregnancy: A Trimester-by-Trimester Guide

ACOG Recommendations: 150 Minutes a Week

The American College of Obstetricians and Gynecologists (ACOG) recommends that people with an uncomplicated pregnancy get at least 150 minutes of moderate-intensity aerobic activity per week, spread across most days — the same general target recommended for non-pregnant adults. This can include brisk walking, swimming, stationary cycling, and prenatal-specific fitness classes.

For those who were already regularly exercising, including at vigorous intensity, before pregnancy, ACOG guidance generally supports continuing at a similar or moderately reduced intensity with provider clearance, rather than needing to stop entirely. Starting from scratch during pregnancy, however, should begin at a lower intensity, building up gradually.

Based on: American College of Obstetricians and Gynecologists. "Physical Activity and Exercise During Pregnancy and the Postpartum Period." Committee Opinion No. 804. Obstet Gynecol. 2020;135(4):e178-e188. PubMed ↗

Safe vs Avoided Exercises by Trimester

As pregnancy progresses, balance and centre of gravity shift, which is why fall-risk activities (downhill skiing, horseback riding, contact sports) are generally recommended against throughout, and become an increasing consideration as the third trimester progresses. Lying flat on the back for prolonged periods is generally advised against from the second trimester onward, as the growing uterus can compress a major blood vessel and reduce blood flow.

Warning Signs to Stop Exercising Immediately

Stop exercising and contact your obstetric provider promptly if you experience any of the following during or after activity:

• Vaginal bleeding or fluid leaking from the vagina
• Regular, painful contractions
• Dizziness, faintness, or feeling like you might pass out
• Chest pain or unusual shortness of breath before exertion
• Calf pain or swelling (possible sign of a blood clot)
• Headache that doesn't resolve or muscle weakness affecting balance
• Decreased fetal movement (in the second half of pregnancy)

These are signs to seek medical attention promptly rather than symptoms to "push through" — unlike normal exercise fatigue, they may indicate a pregnancy complication unrelated to fitness level.

Why Medical Clearance Matters

Certain conditions — including some forms of heart or lung disease, incompetent cervix, persistent second or third trimester bleeding, placenta previa after 26 weeks, preeclampsia, and severe anemia — are contraindications to exercise during pregnancy, or require significant modification. This is why obtaining clearance from your obstetric provider before starting or continuing an exercise routine is a foundational first step, not just a formality, and why general population guidelines should always defer to your provider's individualised assessment of your specific pregnancy.

Once cleared, use our Pregnancy Weight Gain Calculator alongside consistent, moderate activity to support a healthy pregnancy trajectory, and see our Pregnancy Weight Gain Guide for the full IOM recommended gain ranges by pre-pregnancy BMI.