Which exercises are safe in each trimester?

In an uncomplicated pregnancy with clearance from your doctor or midwife, almost everything you were already doing stays safe through all three trimesters — walking, stationary cycling, swimming, strength training, mat-based core and pelvic floor work. What changes across the trimesters is position, balance demand and how hard you brace, not the list of exercises.

The short version: the first trimester usually changes nothing except how you feel; the second trimester changes positions — less time flat on your back, less maximal bracing, more support for balance; the third trimester narrows the range of comfortable positions rather than the amount you can do. Contact sports, scuba diving and anything with a real risk of falling are out from the start, and bleeding, leaking fluid, chest pain or regular painful contractions mean you stop and get checked.

How much exercise should I be doing in total?

The weekly target does not change between trimesters. The 2020 WHO guidelines on physical activity recommend that pregnant and postpartum women without contraindications do at least 150 minutes of moderate-intensity aerobic activity per week, add muscle-strengthening work on at least two days, and may do pelvic floor muscle training daily to reduce the risk of urinary incontinence. ACOG and the CDC give the same 150-minute figure and say it can be spread across the week in whatever blocks fit your day.

That is the floor, not the ceiling. If you were training five days a week before pregnancy, the guidance does not ask you to cut back to three. If you were doing nothing, pregnancy is a reasonable time to start — see Can I join at any stage of pregnancy?.

First trimester (weeks 1–13): what actually changes?

Usually nothing in the programme. Often a lot in how you feel.

What continues

• Barbell and dumbbell work — squats, deadlifts, presses, rows — at the loads you were already using, provided your technique and breathing are unchanged.
• Running, cycling, swimming and classes you were doing before, at your usual intensity.
• Flat lying positions are still fine at this stage, so bench press and floor work need no modification yet.
• Pelvic floor training, which is easiest to build into a habit now while nothing else is uncomfortable. See How do I do pelvic floor exercises properly?.

What to modify

• Nausea and fatigue, not risk, are the usual reason to cut volume. Shorter sessions done consistently beat long sessions abandoned halfway.
• Train in the coolest part of the day and drink more than you think you need, particularly in Jeddah's humidity.
• Expect your heart rate to sit higher at the same effort. Judge intensity by effort, not by the number on the watch.

ACOG's committee opinion on exercise in pregnancy is clear that physical activity in an uncomplicated pregnancy has not been shown to increase the risk of miscarriage or preterm birth. Early pregnancy is not a reason to stop lifting.

Second trimester (weeks 14–27): what should I change?

This is where real modifications start, and there are three of them.

• Time spent flat on your back. The NHS advises avoiding lying flat on your back for long periods after about 16 weeks, because the weight of the uterus can press on a major vein and make you feel faint. A set of chest press is not a long period, but a whole session of floor work is. Move to an incline bench, a side-lying position or standing variations.
• Balance. Your centre of gravity moves forward as the bump grows. Keep single-leg work, but hold something — rear-foot-elevated split squats with a rack to touch, step-ups with a rail. Lose the unsupported, high-skill balance drills.
• Bracing. Stop breath-holding through maximal lifts. Breathe out on the hard part of the rep and choose loads you could repeat two or three more times. Watch the midline: if the front of your abdomen cones or domes into a ridge during an exercise, reduce the load or the range rather than pushing through. How do I know if I have diastasis recti? explains what that ridge means and what it does not.

Traditional sit-ups, crunches and double-leg lowering are usually the first things to go, not because they are dangerous but because they are the exercises most likely to produce that coning. Side planks, dead bugs within a controlled range, loaded carries and anti-rotation work do more for you anyway.

The exercise list barely changes across the three trimesters. The position you do it in, the way you breathe through it and the rest you take between sets change a great deal.

Third trimester (weeks 28 to birth): what is still worth doing?

Most of it. The limiting factor is usually the bump, your breathing and your pelvis — not safety.

• Range of motion shrinks before load does. A deadlift from blocks or a trap bar, a front-racked squat to a box, an incline press instead of a flat one. Same muscles, workable positions.
• Breathlessness arrives earlier. Longer rests, fewer reps per set, more sets. You are not losing fitness by splitting the work up.
• Pelvic girdle pain is common and treatable. RCOG's guidance on pelvic girdle pain describes pain at the front or back of the pelvis that worsens with walking, stairs and standing on one leg, and recommends assessment and treatment by a physiotherapist. If single-leg work, wide stances or turning in bed hurt, narrow your stance, keep your legs closer together when moving, and ask for a referral. Do not train through sharp pelvic pain.
• Keep walking. It is the single most reliable thing in the last weeks, and it is also the thing most likely to be dropped.

What training in this period does and does not do for labour is covered in Will training make labour easier? — the honest answer is that it improves the parts you control.

What should I avoid in every trimester?

• Contact sports — football, basketball, judo, boxing — because of the risk of a blow to the abdomen.
• Activities with a real risk of falling, such as horse riding, skiing, gymnastics and outdoor cycling on rough or busy roads, as the NHS advises.
• Scuba diving, which the NHS says to avoid throughout pregnancy because the baby cannot protect against decompression sickness.
• Exercising at altitudes above around 2,500 metres until you have acclimatised.
• Hot yoga and hot Pilates, which ACOG advises against because of the risk of overheating.
• Maximal lifts, one-rep-max attempts and long breath-holds at any stage.

How do I know the intensity is right?

Use the talk test, which ACOG recommends as a practical gauge: if you can hold a conversation while you train, the intensity is moderate. If you can only manage a few words, ease off. A short, honest rating of effort out of ten works just as well — keep strength sets around a seven, with two or three reps left in reserve.

Stop and get help

Stop exercising and contact your doctor, midwife or emergency services if you have:

• Vaginal bleeding, or fluid leaking from the vagina.
• Regular painful contractions.
• Chest pain, or shortness of breath that starts before you exert yourself.
• Dizziness or feeling faint that does not pass with rest.
• Headache that is severe or unusual for you.
• Calf pain or swelling on one side.
• Muscle weakness that affects your balance.
• Sharp pelvic or abdominal pain that persists after you stop.

This is general information, not medical advice for your pregnancy. If you have a placenta problem, cervical weakness, pre-eclampsia, significant bleeding or a multiple pregnancy, your own obstetrician's instructions override everything on this page. Is it safe to train during pregnancy? lists the conditions that rule training out.

Where to start

1. Ask your doctor or midwife at your next appointment whether there is any reason you should not exercise. One question, written answer if you can get it.
2. Set a weekly shape: two strength sessions and enough walking to reach roughly 150 minutes of moderate activity across the week.
3. Make the trimester-appropriate swaps in advance — incline instead of flat, supported instead of free-standing, exhale instead of breath-hold — rather than waiting until something feels wrong.
4. Start daily pelvic floor work now, whatever trimester you are in.
5. If anything on the stop list happens, stop that day and get checked before you train again.