Pilates During Pregnancy: A Trimester-by-Trimester Guide

In the eight hundred or so pre/postnatal clients I've worked with, almost none have had a bad experience with Pilates during pregnancy. The bad experiences come from doing the wrong exercises at the wrong times, or from instructors who don't understand what's actually changing in a pregnant body. Here's what you need to know, trimester by trimester.

If you're starting from scratch

If you've never done Pilates before and you're pregnant, you can still start — but with two caveats. First, get clearance from your provider. Second, find a pre/postnatal certified instructor for at least your first 4-6 sessions. Group prenatal classes are usually safe; standard Pilates classes are not specifically designed for pregnant bodies and the instructor may not know how to modify for you.

First trimester (weeks 1-13)

This is the trimester of greatest uncertainty for most women, and also the one where the least modification is needed. The body hasn't yet changed shape significantly. Hormonal shifts are the bigger issue: relaxin (the hormone that loosens ligaments to prepare for birth) is already circulating, which means your joints may be slightly more mobile than usual.

What to do: Almost any beginner-to-intermediate Pilates exercise is fine. Continue what you were doing before pregnancy, but be cautious about pushing your range of motion into stretches you haven't routinely done — increased ligament laxity makes injury more likely.

What to modify: Reduce intensity if you're experiencing fatigue or nausea (common in this trimester). Avoid breath-holding under exertion (the Valsalva maneuver), which can spike blood pressure.

What to drop: Nothing yet, in most cases. If you have a history of miscarriage or are high-risk, defer entirely to your provider.

Second trimester (weeks 14-27)

This is when modifications begin in earnest. Your belly is growing, your center of gravity is shifting forward, and lying flat on your back becomes less comfortable.

Around week 16-20: Stop doing exercises that involve lying flat on your back for extended periods (more than about 90 seconds). This is the standard supine restriction in pre/postnatal exercise. Brief moments on your back during transitions are fine. Use a wedge pillow or set up at an incline for any work that would otherwise be supine.

Modify these: The hundred (do it at an incline, or replace with seated breathing). Roll-up (modify to half roll-back from seated). Single leg circles (perform from a side-lying or all-fours position). Plank (drop to forearms, or perform from a wall at an incline).

Add these: Side-lying leg work (clamshells, leg lifts) becomes especially important for hip stability. Wall squats. Cat-cow for spinal mobility. Pelvic floor activation exercises — these matter enormously for birth and recovery and are often skipped.

Third trimester (weeks 28-40)

The body changes significantly in this trimester. Your bump is large; your balance is off; relaxin levels peak; and many positions become uncomfortable.

What to do: Standing work (squats, wall slides, hip openers). All-fours work (cat-cow, bird dog without the leg lift, modified clamshells). Side-lying work (still excellent). Seated and standing breathing practice.

What to drop: All supine work (lying on your back), all prone work (lying on your stomach — for obvious reasons), and most flexion exercises (anything that crunches the abdomen forward).

Birth preparation focus: Breath practice becomes the most useful single thing you can do in third-trimester Pilates. Practicing 360-degree breathing — into the back, sides, and pelvic floor — directly translates to managing contractions in labor. More on Pilates breathing here.

Exercises to drop entirely from second trimester onward

• Roll-up (full version)
• Teaser
• Jackknife
• Double-leg stretch (full version)
• Crisscross (criss-cross)
• Hundred (full version)
• Any prone (face-down) exercise from second trimester on
• Any deep twist that brings the shoulder across the bump
• Plank longer than 20 seconds (or any plank in third trimester)

These exercises stress or load the rectus abdominis (the long abdominal muscle that separates during pregnancy as diastasis recti). Continuing them during pregnancy makes the diastasis worse and the postpartum recovery slower.

When to stop and call your provider

Stop exercising immediately and call your provider if you experience any of: vaginal bleeding, regular painful contractions, leaking fluid, dizziness or fainting, headache, chest pain, calf swelling or pain, decreased fetal movement, or persistent muscle weakness affecting balance. None of these are normal during exercise.

Beyond those red flags, the most reliable indicator that you're working too hard is the talk test: if you can hold a conversation while exercising, you're at appropriate intensity. If you're gasping, slow down.

Pilates during pregnancy, done well, is one of the kindest things you can do for your body during a season when nothing else feels easy. For postpartum recovery, my dedicated guide is here.

Frequently asked

Is it safe to start Pilates if I've never done it before and I'm pregnant?

Yes, with the right instructor. Look for a pre/postnatal certified instructor (PCES, BirthFit, or similar credential) for at least your first few sessions. Group classes labeled as 'prenatal' are generally safe; regular Pilates classes may not be.

Can Pilates cause miscarriage in the first trimester?

There is no evidence that moderate exercise, including Pilates, causes miscarriage in healthy pregnancies. Most miscarriages in the first trimester are due to chromosomal abnormalities, not exercise. That said, your provider's specific recommendations always take precedence.

When should I stop doing Pilates exercises on my back during pregnancy?

Most providers recommend avoiding extended periods lying flat on the back after the second trimester (around 16-20 weeks), as it can compress the vena cava in some women. Brief moments lying on the back during exercise transitions are generally fine.

Can I keep doing the hundred while pregnant?

Modified, yes — into the second trimester. The traditional hundred (lying flat, head and shoulders lifted) should be modified by mid-second trimester to an incline (using a wedge or pillows) and dropped entirely by third trimester. Replace with seated breathing variations.