Reformer Pilates has a reputation for being intense, which makes women who love it wonder whether they should stop the moment they see a positive test. For most, the answer is no — but the practice has to change, and the change is more than “take it a bit easier”. The reformer’s sliding carriage, spring resistance and the sheer number of exercises done lying on your back all need rethinking as the trimesters progress. Done well, prenatal reformer work is one of the best ways to stay strong, keep back and pelvic pain at bay and prepare the pelvic floor for birth. Done without modification, it can leave you dizzy, strained or sore. This guide covers what to change, when, and how to get the same benefits on a mat at home.
Key takeaway: Reformer Pilates is safe for most uncomplicated pregnancies when taught by a prenatally trained instructor and modified by trimester: lighter springs and no breath-holding throughout; no crunches, hundreds or roll-ups; no prolonged lying flat after about 16–20 weeks (use an incline or side-lying); no prone work; no deep twists or end-range stretching. Get your obstetric team’s go-ahead and tell your instructor early.
Reformer Pilates is safe during pregnancy for most women without complications, provided it is modified appropriately. Key changes are lighter spring settings with continuous breathing; replacing abdominal flexion exercises such as the hundred and roll-ups with deep core and pelvic floor work; avoiding prolonged supine positions after about 16–20 weeks by using an incline box, side-lying or seated work; dropping prone and deep-twist exercises; and avoiding end-range stretching because pregnancy hormones loosen the joints. Sophie Mercer, PMA-certified clinical Pilates instructor, designed a 6-week Pregnancy (Second Trimester) protocol of 24 exercises that applies these same modifications on a mat at home.
Is reformer Pilates safe during pregnancy?
Clinical guidelines encourage regular moderate exercise through an uncomplicated pregnancy, and Pilates — reformer included — fits that advice well because it is low impact, controllable and easy to scale. The reformer even has some advantages: the straps and springs support the limbs, the footbar allows leg strengthening without standing balance, and the box and carriage make side-lying and inclined positions easy to set up.
The caveats are real, though. Springs invite breath-holding; the carriage is unstable to stand on; and a huge share of the classical repertoire is performed lying flat. Your instructor needs prenatal training, and you need clearance from your midwife or obstetric team — especially if you have bleeding, placenta praevia, pre-eclampsia, a history of preterm labour, significant pelvic girdle pain or any other complication. If you are new to Pilates, start with gentle mat work rather than jumping onto a reformer for the first time pregnant; is Pilates safe during pregnancy? sets out the general rules.
First trimester (weeks 1–13): keep going, scale down
Tell your instructor as soon as you know. Physically, most of the repertoire is still available, but fatigue, nausea and a higher resting heart rate are common, so:
- Lower spring tension and stop chasing the burn.
- Never hold your breath — exhale on the effort of every push and pull.
- Avoid overheating; hydrate, and skip heated studios.
- Begin easing off deep abdominal flexion (hundred, roll-ups, teaser) now rather than later, so the habit is built by the time it matters.
- Stop if you feel dizzy, breathless or unwell.
Second trimester (weeks 14–27): the main modifications
This is usually the most comfortable phase and the one where the meaningful changes happen.
- Supine work: from around 16–20 weeks, the weight of the uterus can compress the major vein returning blood to the heart when you lie flat, causing dizziness and reduced blood flow. Use the box on an incline, a wedge under the back, or switch to side-lying and seated versions. Footwork can be done with the headrest up and a wedge, or on a raised box, for a limited time if you feel fine — but if you feel light-headed, come up immediately.
- Abdominal work: replace flexion with deep core and pelvic floor training — kneeling and seated arm work with an exhale-and-lift, side-lying leg work in straps, and quadruped (all-fours) patterns. Watch for doming along the midline of the belly; if it appears, the exercise is too much.
- Prone work: swan, pulling straps and anything face-down come out. Substitute kneeling or standing back extension against the springs.
- Twists: keep rotation upper-body only and gentle; no deep twists across the belly.
- Stretching: relaxin makes ligaments looser than they feel. Stay in mid-range on hip, hamstring and adductor stretches; avoid the splits-type stretches in the straps.
- Pelvic girdle and SI joint pain: keep the legs closer together on footwork, avoid wide single-leg positions, and move symmetrically. The principles in SI joint pain exercises carry across to the reformer.
Third trimester (weeks 28–40): comfort, balance and preparation
- Favour seated, kneeling, side-lying and standing-at-the-footbar work.
- Reduce range and load further; the goal is maintenance and comfort, not progress.
- No standing on the carriage, no jumpboard, no long planks.
- Prioritise pelvic floor release as well as lift — the ability to let go matters for birth. Pelvic floor exercises during pregnancy covers both halves.
- Hip mobility (circles, gentle openers in mid-range), upper back extension for posture, and breathing into the back ribs are the priorities.
- Rest whenever you need to.
What to avoid on the reformer while pregnant
The hundred, roll-ups, teasers, short spine and overhead inversions; prone exercises; standing on the moving carriage; jumpboard; heavy springs with breath-holding; deep twists; end-range stretches; and, after mid-pregnancy, prolonged flat supine work. Stop and seek advice if you have bleeding, fluid loss, contractions, dizziness, chest pain, calf pain or swelling, headache with visual changes, or reduced fetal movement.
Mat alternatives at home
You do not need the machine to get the benefits. Most prenatal reformer exercises have a direct mat equivalent: footwork becomes wall squats and bridges on an incline; arm work in straps becomes band work seated or kneeling; side-lying leg series is identical on a mat; kneeling back extension against springs becomes band rows and quadruped reaches. A large ball replaces most supine positions — see Pilates ball exercises for pregnancy for a full routine. If you enjoy reformer-style flow, reformer Pilates at home without the machine shows how to replicate it with a band and a mat, though it is not pregnancy-specific and needs the same modifications above.
How the Pregnancy (Second Trimester) protocol helps
Sophie’s 6-Week Pilates Program for Pregnancy (Second Trimester) is the mat-and-props version of a well-modified prenatal reformer class: 24 exercises covering leg and glute strength, upper back and posture, deep core and pelvic floor coordination, hip mobility and back care, with the supine, prone, flexion and twist restrictions already built in. It gives you a structured routine for the weeks between studio sessions, or a complete alternative if reformer classes are not available or not comfortable.
This article is for informational purposes only and does not constitute medical advice. Please check with your midwife, obstetrician or a pelvic health physiotherapist before starting or continuing reformer Pilates in pregnancy, tell your instructor you are pregnant, and stop and seek advice immediately if you experience bleeding, fluid loss, contractions, dizziness, chest pain, calf pain or reduced fetal movement.