HIIT in Pregnancy & Postpartum: What the Science (and Your Body) Say
Here’s a friendly, science-informed guide you can actually use—plus where to find OB/GYN-reviewed HIIT inside Expect.
A quick Expect update (and a proud moment)
Expect features multiple HIIT workouts inside the app, all reviewed by OB/GYNs for safety with clear modifications for each trimester and after birth. Our signature prenatal HIIT workout is led by certified instructor Maurice Johnson (Equinox and Life Time Fitness alum—and a dad). Maurice and his pregnant wife also opened Expect’s warm-up for the March for Babies launch event in New York—proof that “expecting” and “energized” go together.
What counts as HIIT?
HIIT (High-Intensity Interval Training) means short bursts of harder work—think 30 to 60 seconds—followed by easy recovery periods, all squeezed into 15 to 30 minutes. You can keep it low-impact (power walking, step-backs, cycling, boxing drills) and still get all the benefits.
HIIT isn’t just safe—here’s why it’s actually really good for you
1) Keep your fitness during pregnancy
Research shows that pregnant women who do HIIT workouts can maintain their cardiovascular fitness throughout pregnancy, while those who don’t exercise tend to lose fitness as the months go on. Some studies even show improvements in body composition. And in the general population, HIIT often matches or beats traditional steady cardio for building fitness—in less time. One study found that people doing HIIT gained about double the cardiovascular improvements compared to moderate training.
2) Better blood sugar control
Multiple studies show that HIIT improves insulin sensitivity (how well your body processes sugar) better than steady-state cardio. This is especially valuable during pregnancy, when your body naturally becomes more insulin-resistant, and after birth when your metabolism is resetting. (See an additional overview.)
3) Body composition benefits
A major review suggests interval training produces small but significantly greater reductions in total body fat compared to moderate cardio—plus it’s more time-efficient, which matters when you’re a busy mom.
4) Mental health boost
In one study with pregnant women, the HIIT group (not the light-activity group) showed significant improvements in mental health measures. Another study found favorable changes in both psychological functioning and stress hormones after 8 weeks of HIIT. That post-workout high is real—and incredibly valuable during pregnancy.
5) Safe for baby
When researchers compared HIIT to moderate cycling, both moms and babies did well: fetal heart rate and blood flow to the placenta stayed in healthy ranges in uncomplicated pregnancies. Even high-intensity resistance exercise has been shown to be well tolerated by both mother and fetus in controlled settings.
How to make HIIT work for pregnancy and postpartum
Green-light checklist
Get clearance from your OB/GYN or midwife, especially if you have any complications. ACOG recommends 150 minutes per week of physical activity and outlines safety signals and modifications.
Use perceived effort, not your pre-pregnancy standards. Intervals should feel “challenging but controlled” with good form and quick recovery.
Stay cool and hydrated. Work out in a ventilated space, take water breaks, and stop if you feel dizzy or overheated.
Easy modifications
Late pregnancy: Swap jump squats for squat-to-calf-raises, burpees for step-back burpees or incline walk-outs, and sprints for power-walk hills or bike intervals.
Avoid lying flat on your back for long periods after the first trimester; use an incline instead.
Postpartum pacing
Think “windows, not deadlines.” Many clinicians recommend about 3 to 6 months before returning to high-impact running or jumping—but it depends on your symptoms and pelvic-floor health.
Start with breathing exercises, pelvic-floor work, glute strengthening, and low-impact cardio. Add intensity only after you’re symptom-free (no leakage, pelvic heaviness, “doming” of your belly, or pain). And good news: research shows that regular exercise doesn’t reduce milk volume or change its composition if you’re breastfeeding.
Red-flag stop list
Stop immediately and call your doctor if you experience: bleeding, chest pain, regular painful contractions, fluid leakage, severe headache, calf pain or swelling, dizziness, or new or worsening pelvic symptoms.
Try this: 15-minute “any-trimester” low-impact HIIT
Work for 40 seconds, rest for 20 seconds × 2 rounds (60 seconds rest between rounds):
Squat to calf-raise
Elevated incline push-ups (bench or wall)
Alternating step-back lunges
Band rows or standing “T” pulls
Marching high knees (low impact)
Modify or shorten at the first sign of symptoms.
Where to start inside Expect
Signature: Maurice Johnson’s prenatal HIIT class “The Big HIIT.”
More HIIT inside the app: Additional HIIT classes, all OB/GYN-reviewed, with clear prenatal and postpartum modifications so you can press play without worrying about safety.
The bottom line
For many expecting and new moms, HIIT offers a powerful, time-efficient way to maintain (or regain) fitness, protect metabolic health, and boost mood—not just something you “can get away with.” With your provider’s clearance, smart modifications, and a careful return postpartum, intervals can be one of the most practical ways to feel strong through pregnancy and into life with baby.