Exercising While Pregnant: Pros and Cons

This article is an excerpt from the Shortform summary of "Expecting Better" by Emily Oster. Shortform has the world's best summaries of books you should be reading.

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Want to keep active while you’re pregnant? That’s great. But you should know some pros and cons of exercising while you’re pregnant. Learn the good exercises and bad exercises of exercising while pregnant.

Exercising When You’re Pregnant Dos and Don’ts

First of all, is exercising while pregnant actually good for you and the baby?

There is little evidence suggesting that exercise has any effects on preterm birth, rate of C-section, length of labor, or baby APGAR scores. Exercise does show a modestly lower weight gain (1.3 fewer pounds). 

Here are specific exercises to consider and to avoid:

Exercises to consider while pregnant:

  • Kegels
    • These exercise your pelvic floor muscles
    • 3 sets of 8 kegels per day improves urinary continence during late pregnancy and postpartum
    • A small study showed women in Kegels experimental group showed shorter time pushing (40 vs 45 minutes)
  • Prenatal Yoga
    • Small studies suggest yoga reduces discomfort in late pregnancy, decreased length of labor (2.5 hours shorter), and lower levels of pain during labor

Exercises to avoid:

  • Exercise with risk of physical trauma or falling (skiing, football, climbing) can cause the placenta to detach
  • Very high heart rate exercise (eg 90% of max) can decrease blood flow to baby
  • Doctors suggest avoiding sit-ups or crunches where you lie flat on your back, since this may drop blood pressure and reduce blood flow.
    • Oster suggests this is actually fine; if you feel uncomfortable while doing it, then just stop.


Sleeping may be tough in later pregnancy due to aches and positioning issues.

The recommendation is to sleep on the left side, not the back. The evidence is currently inconclusive – some studies show sleeping on the back or right side doubled stillbirth rate. However, a blood flow study found that lying on your back found no particularly bad impact on blood flow. 

Some women feel faint on their backs – if so, then they should switch to their left side. If you don’t feel faint, it’s probably fine, though if you can sleep on your left, that’s preferred.

Taking OTC sleep aids like Unisom are fine. Ambien has mixed safety data, but Oster believes it’s fine occasionally.

Exercising While Pregnant: Pros and Cons

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Here's what you'll find in our full Expecting Better summary :

  • Why much parenting advice you hear is confusing or nonsense
  • The most reliable way to conceive successfully
  • How much alcohol research shows you can drink safely while pregnant (it's more than zero)
  • The best foods to eat, and what foods you really should avoid

Allen Cheng

Allen Cheng is the founder of Shortform. He has a passion for non-fiction books (having read 200+ and counting) and is on a mission to make the world's best ideas more accessible to everyone. He reads broadly, covering a wide range of subjects including finance, management, health, and society. Allen graduated from Harvard University summa cum laude and attended medical training at the MD/PhD program at Harvard and MIT. Before Shortform, he co-founded PrepScholar, an online education company.

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