Exercise during pregnancy: what the guidelines actually say

Exercise during pregnancy is not the fragile, do-as-little-as-possible situation gym folklore makes it out to be. The official guidance is clear: if your pregnancy is uncomplicated, staying active is safe and recommended, and if you already trained before, you can generally keep going with some changes. What changes, and who decides, is the useful part.

This post sticks to what the guidelines actually say: the American College of Obstetricians and Gynecologists (ACOG), the World Health Organization (WHO) and the NHS. No influencer bump workouts, no promises. Whether you plan your own training or use one plan for running and lifting, the rules below are the same.

Before anything else: check with your doctor, midwife or a pelvic health physiotherapist before starting, continuing or changing your training in pregnancy. Every recommendation below assumes an uncomplicated pregnancy and a care provider who has said yes. Nothing here is medical advice.

Is exercise during pregnancy safe? The short answer

For most women, yes. ACOG's Committee Opinion 804 says that in the absence of obstetric or medical complications or contraindications, physical activity in pregnancy is safe and desirable, and that pregnant women should be encouraged to continue or to start safe physical activities (ACOG, 2020). It also says a thorough clinical evaluation should come before an exercise program, to make sure there's no medical reason to avoid exercise.

The NHS puts it more bluntly: exercise is safe for you and your baby in pregnancy, start any new exercise gently, and it's usually fine to keep doing activities you already do (NHS).

So the default isn't "stop". The default is "keep moving, adjust, and get your care provider's sign-off". If you were following a strength plan for women before you were pregnant, the question is how to adapt it, not whether to bin it.

If you've been lifting for years and are wondering how pregnancy fits into a longer training life, there's more on strength training for women over 40, which covers the decades around it.

How much exercise during pregnancy is recommended?

The three main bodies land in the same place.

Sources: Bull et al., 2020 (the WHO 2020 guidelines), ACOG 804 and the NHS page linked above.

A few details worth knowing:

• ›The WHO guidelines recommend that all pregnant and postpartum women without contraindication do regular physical activity throughout pregnancy and postpartum, and limit time spent sedentary. Women who habitually did vigorous-intensity aerobic activity or were physically active before pregnancy can continue those activities during pregnancy and the postpartum period (Bull et al., 2020).
• ›If you're new to exercise, the NHS suggests starting with a smaller amount, like 10 minutes a day, and building slowly toward 150 minutes a week. If you can't hit 150, do what you can. Any activity is better than none.
• ›Sessions don't have to be long. The NHS notes you can split the 150 minutes into shorter sessions every day or spread them across a few days.

How hard should you go?

Moderate, for most people, most of the time, measured by how it feels rather than a number on a watch.

ACOG says that because heart-rate responses to exercise can be blunted in pregnancy, ratings of perceived exertion may be a more effective way to monitor intensity than heart-rate targets. For moderate intensity, that's 13–14 ("somewhat hard") on the 6–20 Borg scale. The other tool is the talk test: as long as you can carry on a conversation while exercising, you're likely not overexerting yourself (ACOG, 2020). The NHS version: you should be able to talk but not sing.

What about harder training? ACOG says an upper level of safe exercise intensity hasn't been established, and that women who were regular exercisers before pregnancy and have uncomplicated, healthy pregnancies should be able to do high-intensity programs such as jogging and aerobics with no adverse effects. It also notes that high-intensity or prolonged exercise beyond 45 minutes can lead to low blood sugar, so eat enough beforehand or limit the intensity or length of the session.

Competitive and elite athletes are a separate case. ACOG says they need frequent, close supervision and should get approval from their health care providers before continuing strenuous training.

What kind of exercise is recommended in pregnancy?

ACOG lists these as extensively studied in pregnancy and found to be safe and beneficial:

• ›Walking
• ›Stationary cycling
• ›Aerobic exercises
• ›Dancing
• ›Resistance exercises (for example, weights and elastic bands)
• ›Stretching exercises
• ›Hydrotherapy and water aerobics

If you want those turned into sessions, a pregnancy workout routine builds a week from them.

Running isn't on that list, but it isn't banned either. It has its own rules, covered in the post on running while pregnant. The NHS line is that starting a new vigorous activity like running in pregnancy isn't recommended, while carrying on with one you already do is usually fine.

Strength training while pregnant

Lifting is in. ACOG says women with uncomplicated pregnancies should be encouraged to do aerobic and strength-conditioning exercises before, during and after pregnancy. The NHS says muscle-strengthening can include strength training at a gym if you already do it.

What the guidance doesn't give you is a rep scheme. ACOG notes the research on resistance training in pregnancy, especially heavy training by athletes, is sparse, and suggests elite athletes consider decreasing resistance load compared with before pregnancy. In practice that means:

• ›Keep the movements you know. Pregnancy isn't the time to learn a max-effort snatch.
• ›Lighter than your pre-pregnancy numbers is the documented direction, and your care provider sets the boundaries.
• ›Avoid long periods lying flat on your back (more on that below).

What to avoid during pregnancy

The guidance is short and specific.

• ›Lying flat on your back for long stretches. ACOG notes that lying on your back during exercise after 20 weeks can reduce blood return to the heart and cause low blood pressure, and advises avoiding long periods lying flat. The NHS says to avoid activities that involve lying flat on your back for more than a few minutes in later pregnancy. Swap flat bench presses for incline versions and floor work for side-lying or seated options. This is one of several things that shift as you go, which is why how training changes each trimester gets its own guide.
• ›Contact and fall-risk sports. ACOG says to avoid contact activities with a high risk of abdominal trauma or imbalance. The NHS names hockey, rugby and mountain biking as examples.
• ›Scuba diving. Both ACOG and the NHS say to avoid it.
• ›Heat. ACOG advises staying well hydrated, wearing loose clothing, and avoiding high heat and humidity, particularly in the first trimester. Prolonged sessions belong in a cool or air-conditioned environment.
• ›Training on an empty stomach. The NHS says not to, as it could make you faint.

The NHS also says to tell your trainer or instructor you're pregnant. Obvious, until you're in a class that programs lying-down crunches.

Warning signs: when to stop exercising

ACOG's Box 3, "Warning Signs to Discontinue Exercise While Pregnant", lists these, word for word (ACOG, 2020):

• ›"Vaginal bleeding"
• ›"Abdominal pain"
• ›"Regular painful contractions"
• ›"Amniotic fluid leakage"
• ›"Dyspnea before exertion" (dyspnea means shortness of breath)
• ›"Dizziness"
• ›"Headache"
• ›"Chest pain"
• ›"Muscle weakness affecting balance"
• ›"Calf pain or swelling"

The NHS adds a simpler rule: "stop if you feel uncomfortable, too hot or unwell."

If any of these happen, stop, and contact your doctor or midwife. That's not a training decision.

What exercise during pregnancy may help with

Here's where the internet overpromises, so the wording matters.

The WHO guidelines say physical activity during pregnancy and the postpartum period confers benefits including reduced risk of pre-eclampsia, gestational hypertension, gestational diabetes, excessive gestational weight gain, delivery complications and postpartum depression, with no increase in risk of stillbirth, newborn complications or adverse effects on birth weight (Bull et al., 2020).

ACOG's conclusion is more careful: although the evidence is limited, exercise results in benefits to pregnancy outcomes, there's no evidence of harm when exercise isn't contraindicated, and exercise may reduce the risk of gestational diabetes, preeclampsia and cesarean birth. "May reduce the risk" is the wording, and nobody should feel blamed for a complication because they skipped a workout.

After pregnancy, and the rest of the decade

Training doesn't end at birth, but it does restart slowly. Postpartum return to running follows its own published guideline with time-based criteria and symptom checks, and getting back under a barbell is the subject of postpartum strength training, which needs the same care. If you had a caesarean, exercise after a C-section covers the slower timeline.

The bigger picture is that hormones and training keep interacting for decades. Training with your menstrual cycle is where most women start, and menopause exercise explained covers the other end. Conditioning raises its own questions later in life too, and hiit workouts for women over 50 explained is a separate topic with separate guidance.

How exrsz handles this

exrsz builds a periodized plan from your goal, schedule, level and equipment, balances running and lifting in one plan, adapts each week to how you actually trained, and reshuffles missed sessions instead of stacking them up. It doesn't give medical advice, and it isn't a substitute for the person managing your pregnancy. Check with your doctor, midwife or a pelvic health physiotherapist first, then train within what they've agreed.

FAQ

Is exercise during pregnancy safe?

For most women with an uncomplicated pregnancy, yes. ACOG says physical activity in pregnancy is safe and desirable in the absence of obstetric or medical complications or contraindications (ACOG, 2020). Check with your doctor or midwife first.

How much exercise should I do while pregnant?

The WHO recommends at least 150 minutes of moderate-intensity aerobic activity a week, plus a variety of aerobic and muscle-strengthening activities (Bull et al., 2020). The NHS suggests including 2 strength sessions a week (NHS).

Can I lift weights while pregnant?

ACOG lists resistance exercise with weights or elastic bands among activities studied and found safe and beneficial in pregnancy, and suggests elite athletes consider lowering loads compared with before pregnancy (ACOG, 2020). Avoid long periods lying flat on your back, and agree limits with your care provider.

When should I stop exercising during pregnancy?

Stop and contact your doctor or midwife if you have any of ACOG's warning signs, including vaginal bleeding, abdominal pain, regular painful contractions, amniotic fluid leakage, dizziness, chest pain or calf pain or swelling (ACOG, 2020).

Can I start exercising if I wasn't active before pregnancy?

Yes, gently. The NHS suggests starting with around 10 minutes a day and building up slowly, but says starting a new vigorous activity like running isn't recommended in pregnancy (NHS).