Strong Mama: Why Strength Training Is a Fountain of Youth for Pregnancy and Birth

First, the permission slip you are looking for

Let me get my credentials out of the way: I am a birth doula and a personal trainer. I am not a doctor. But the people who write the guidelines for doctors have something to say here, and I take it seriously.

The American College of Obstetricians and Gynecologists says, in plain language, that women with uncomplicated pregnancies "should be encouraged to engage in aerobic and strength-conditioning exercises before, during, and after pregnancy." Their list of exercises that are extensively studied, safe, and beneficial in pregnancy includes resistance exercises — using weights and elastic bands — right alongside walking and swimming.

The same guideline states that concerns about exercise causing miscarriage, poor fetal growth, injury, or premature delivery "have not been substantiated for women with uncomplicated pregnancies." That is not me being the fun trainer who tells you what you want to hear. That is ACOG Committee Opinion 804.

What the studies found: the actual numbers

I design programs for a living, so I care less about vibes and more about data. Here is what the research actually shows:

• No increased risk of preterm birth. A meta-analysis of 9 randomized trials with 2,059 normal-weight women found preterm birth rates of 4.5% in the exercise group vs 4.4% in controls — essentially identical. The exercising women had a higher rate of vaginal delivery (about 74% vs 68%) and a lower cesarean rate (about 18% vs 22%).
• Better blood sugar and blood pressure. In that same analysis, gestational diabetes was 2.9% vs 5.6% and hypertensive disorders were 1.0% vs 5.6% in exercisers compared to controls. A 2025 review focused specifically on resistance training in pregnancy (50 studies, over 47,000 participants) found that programs including strength work were linked to lower odds of gestational hypertension (odds ratio 0.42), gestational diabetes (0.62), perinatal mood disorders (0.48), and macrosomia, or very large babies (0.67).
• Fewer assisted deliveries. The largest review of the topic — 113 studies, nearly 53,000 women — found that prenatal exercise reduced the odds of instrumental (forceps or vacuum) delivery by 24%. The same review found no link between exercise and preterm rupture of membranes, induction, vaginal tears, fatigue, injury, or diastasis recti.

Two honest caveats, because association is not causation. First, most of these were multicomponent programs (aerobic plus strength), and the resistance doses studied were mostly low to moderate — researchers specifically call for more studies using proper strength-training programming. Second, one big review found no clear link between exercise and cesarean rates while the smaller RCT meta-analysis did find a lower rate. Different study pools, different answers. Science is gloriously specific like that.

Does being strong actually shorten labor?

Here is my favorite study to argue about at dinner parties. In 2018, researchers in Spain randomized 508 healthy pregnant women to either a supervised exercise program (three sessions a week from about week 10, including light resistance, toning, aerobic dance, stretching, and pelvic floor work) or standard care. The exercisers had a shorter first stage of labor — 409 vs 462 minutes, about 53 minutes — and a shorter total labor (450 vs 507 minutes). They were also less likely to use an epidural, and their babies' Apgar scores were unaffected.

But remember that giant 2019 review I just mentioned? It found no overall effect of exercise on the length of labor across all the studies. So the honest version is: one well-run trial found a shorter first stage with a program that included resistance and pelvic floor work; the pooled literature does not confirm it as a general rule. As a trainer, that is still meaningful to me — the program that worked was not "just go for walks." It was programmed strength and pelvic floor work. That is my whole job.

Your pelvic floor is a muscle group too

Ask any trainer which muscle group gets skipped most often and they will say calves. Ask any pregnant woman and she will say the pelvic floor. Mørkved and Bø reviewed 22 trials and concluded that pelvic floor muscle training during pregnancy and after delivery can both prevent and treat urinary incontinence — and the protocols that worked followed strength-training principles: supervised, close-to-maximum contractions, lasting at least 8 weeks.

Read that again: your pelvic floor responds to progressive strength training like any other muscle. Program it like one. (ACOG adds that pelvic floor exercises can be started in the immediate postpartum period, too.)

The diastasis question, and the crunch myth

Somewhere along the way, pregnant women were told that any abdominal work would "cause" diastasis recti and ruin their core forever. The evidence says otherwise:

• A 2023 randomized trial put 70 postpartum women with diastasis recti through a 12-week curl-up program. It did not worsen the separation at all (about 1 mm difference, well within measurement noise) — and it improved abdominal strength and muscle thickness.
• ACOG's guideline notes that postpartum abdominal strengthening, including crunch exercises and the drawing-in maneuver, has been shown to decrease the incidence of diastasis recti and the distance between the abdominals after both vaginal and cesarean birth.
• And that 113-study review? No association between prenatal exercise and diastasis recti.

The fear of training your core during and after pregnancy is mostly just fear. A smart, progressive program that includes deep core and pelvic floor work is protective, not destructive. This is exactly the kind of programming question I love — it is solvable with a good plan, not panic.

How to adjust by trimester

Pregnancy is nine months of your body changing the rules on you. A good program adapts instead of quitting. ACOG's guidance, translated into trainer-speak:

• First trimester: If you were active before, you can generally keep going. Stay hydrated, wear loose clothing, and avoid high heat and humidity — overheating is the main concern early on, not the workout itself.
• Second trimester: After 20 weeks, avoid lying flat on your back for long stretches during exercise (the weight of the uterus can compress the big vein returning blood to your heart). Your center of gravity is shifting, so balance-heavy movements deserve respect. Use the talk test: if you can carry on a conversation, you are not overexerting.
• Third trimester: Aim for the ACOG target of at least 150 minutes of moderate activity per week — roughly 20 to 30 minutes most days — spread through the week. Moderate means a 13 to 14 on the exertion scale: "somewhat hard." Skip contact activities with a real risk of abdominal trauma, and skip scuba diving entirely.
• Every trimester: stop exercising and call your provider if you have vaginal bleeding, abdominal pain, regular painful contractions, fluid leakage, shortness of breath before you even start, dizziness, headache, chest pain, muscle weakness affecting your balance, or calf pain or swelling.

When NOT to exercise: read this with your provider, not instead of them

Okay, trainer hat off for a minute. Here is where my healthy skepticism of one-size-fits-all advice meets genuine respect for medicine: there are real conditions where exercise in pregnancy is off the table, and deciding that is your provider's job, not your Instagram feed's.

ACOG lists absolute contraindications — conditions where aerobic exercise should not be done: hemodynamically significant heart disease, restrictive lung disease, incompetent cervix (or a cerclage), multiple gestation at risk for premature labor, persistent second- or third-trimester bleeding, placenta previa after 26 weeks, premature labor in the current pregnancy, ruptured membranes, preeclampsia or pregnancy-induced hypertension, and severe anemia.

There is also a list of relative contraindications — situations where your provider weighs the risks and may clear you, modify you, or hold you back: anemia, an unevaluated heart arrhythmia, chronic bronchitis, poorly controlled type 1 diabetes, extreme morbid obesity or underweight, a history of being extremely sedentary, intrauterine growth restriction, poorly controlled hypertension, orthopedic limitations, poorly controlled seizure disorder or hyperthyroidism, and heavy smoking.

My philosophy is simple: ask questions, read the evidence, and decide with your provider — never around them. If anything on either list applies to you, the workout can wait until you have had that conversation.

The confidence part — the real fountain of youth

Remember that 2025 resistance-training review? The finding I keep coming back to is not about blood sugar. It is the perinatal mood disorders one: programs that included strength training were linked to roughly half the odds of mood disorders. Half.

Birth asks something enormous of you — physically, emotionally, all of it. Walking in knowing your body is strong and capable changes the experience, and I have watched it happen from both sides of the room: as the trainer who built the program and as the doula who held the hand.

"What an absolute joy it is to coach other women through pregnancy & postpartum while being in the midst of experiencing it myself."

My own story is just one person's experience, not evidence — but I trained through my own pregnancy and had an unmedicated hospital birth with my son. What training gave me was not a guarantee of how birth would go. It gave me trust in my body on the hardest day of my life. You cannot buy that. You build it, one session at a time.

And to be clear about what this is not: as I once posted, "This isn't about 'bouncing back,' and it certainly isn't about weight loss." Strength in pregnancy was never about aesthetics. It is about function, confidence, and recovery. The fountain of youth was never a cream. It is a barbell, a resistance band, and a body you trust.

References

1. Physical Activity and Exercise During Pregnancy and the Postpartum Period: ACOG Committee Opinion, Number 804 — Obstet Gynecol, 2020
2. Exercise during pregnancy in normal-weight women and risk of preterm birth: a systematic review and meta-analysis of randomized controlled trials — Am J Obstet Gynecol, 2016
3. Impact of prenatal exercise on maternal harms, labour and delivery outcomes: a systematic review and meta-analysis — Br J Sports Med, 2019
4. Exercise during pregnancy is associated with a shorter duration of labor. A randomized clinical trial — Eur J Obstet Gynecol Reprod Biol, 2018
5. Resistance training in pregnancy: systematic review and meta-analysis of pregnancy, delivery, fetal and pelvic floor outcomes and call to action — Br J Sports Med, 2025
6. Effect of pelvic floor muscle training during pregnancy and after childbirth on prevention and treatment of urinary incontinence: a systematic review — Br J Sports Med, 2014
7. Curl-up exercises improve abdominal muscle strength without worsening inter-recti distance in women with diastasis recti abdominis postpartum: a randomised controlled trial — J Physiother, 2023
8. Benefits of Resistance Training During Pregnancy for Maternal and Fetal Health: A Brief Overview — Int J Womens Health, 2024

Rachel Gould is a birth doula, personal trainer, and maternal wellness coach serving the Phoenix Valley through Holista Health Collective — 1-on-1 support for preconception, pregnancy, birth, and postpartum.