Exercise in the first trimester: moving gently through tiredness and nausea

The first weeks of pregnancy can be strange ones for movement. From the outside, nothing much has changed. On the inside, you might be more tired than you have ever been, queasy at odd hours, and unsure whether your usual workout is still a good idea. Many people haven't shared their news yet, which can make a class or a training partner feel complicated too.

Here is what the evidence says about exercise in the first trimester, and how to make movement work around the way you actually feel.

Is it safe to exercise in the first trimester?

This is the question underneath many others, so it's worth being clear. The 2019 Canadian guideline, which reviewed the evidence systematically, found that physical activity during the first trimester did not increase the odds of miscarriage or congenital anomalies. It also found that not being active from the first trimester was linked with higher odds of complications such as gestational diabetes, pre-eclampsia and excessive weight gain.^[1] A separate meta-analysis focused on pregnancy loss found no increase in the odds of miscarriage among people who exercised.^[2] ACOG's patient guidance says the same in plain words: physical activity does not increase your risk of miscarriage, low birth weight or early delivery.^[3]

ACOG still recommends talking about exercise with your obstetric care provider at an early prenatal visit, so you know whether anything in your history changes the advice.^[3] In the Eggsports app, until you've confirmed that conversation, sessions stay with gentle breathing, pelvic floor, deep core and mobility work.

How do you exercise with first-trimester fatigue?

Fatigue affects about nine in ten pregnancies at some point, according to the IOC expert group.^[4] The NHS notes it is especially common in the first 12 weeks, when hormonal changes can leave you tired, nauseous and emotional, and recommends resting as much as you can.^[9] The IOC group advises even elite athletes to plan more time for sleep and rest during pregnancy.^[5]

At the same time, the NHS points out that some activity, such as a lunchtime walk or a swim, can help you feel less tired.^[9] That balance looks different every day. A few ideas that tend to help:

• Split movement into 10-minute pieces. ACOG notes these count towards your weekly total just as well as longer sessions.^[3]
• Move at your best time of day, which for many people is not first thing in the morning.
• Swap intensity for consistency: an easy walk most days often feels better than a hard session twice a week.
• Treat a rest day as part of the plan, not a break from it.

The Canadian guideline says it kindly: there may be periods when fatigue or discomfort makes the guidelines impossible to follow, and you are encouraged to do what you can and return to them when you are able.^[1]

If your tiredness is persistent and overwhelming, it's worth telling your doctor or midwife. The IOC group notes that while most pregnancy fatigue is not a sign of illness, it is sensible to rule out causes such as anaemia or thyroid problems.^[4]

Can you exercise with morning sickness?

Nausea affects somewhere between half and four in five pregnant people in early pregnancy, and vomiting around half.^[4] The NHS explains that "morning" sickness can happen at any time of day or night, and that it usually clears up by weeks 16 to 20.^[8] The IOC group notes that most people feel much better by the early second trimester and can then gradually return to their usual routine.^[4]

Some things that can make movement easier on queasy days:

• Don't exercise on an empty stomach. The NHS warns this could make you feel faint.^[7] Small, plain snacks are often easier to manage.
• Sip fluids little and often, which the NHS suggests may help prevent vomiting.^[8]
• Get plenty of rest. Tiredness can make nausea worse.^[8]
• Choose calm, cool movement: an outdoor walk, gentle stretching, or a few minutes with our breathing timer.

There is a more serious form of pregnancy sickness called hyperemesis gravidarum, which affects about 1% of pregnancies.^[4] The NHS advises contacting your midwife or doctor if you are vomiting and cannot keep food or fluids down for 24 hours, have very dark urine or haven't passed urine for more than eight hours, feel very weak, dizzy or faint when standing, have tummy pain or a high temperature, vomit blood, or are losing weight.^[8] Exercise can wait until you're feeling better.

What exercise is safe in early pregnancy?

ACOG describes walking, swimming and water workouts, stationary cycling, and modified yoga and Pilates as among the safest choices in pregnancy. It recommends avoiding contact sports, activities that may lead to a fall, skydiving, scuba diving, hot yoga and hot Pilates, and activities above 6,000 feet unless you already live at altitude.^[3]

Heat deserves a special mention in the first trimester. ACOG advises avoiding overheating, especially early in pregnancy, by drinking plenty of water, wearing loose clothing and exercising in a temperature-controlled room.^[3] The IOC group explains why: during early development, a core body temperature above 39°C may increase the risk of neural tube defects, so hyperthermia should be avoided especially in the first trimester.^[4][5] Reassuringly, exercising at a moderate intensity in a controlled environment for up to an hour does not raise core temperature above 38°C.^[4]

If strength work is part of your routine, see our guide to lifting weights while pregnant for how to adjust as you go.

Should you start or continue exercising in the first trimester?

The WHO says that people who were physically active before pregnancy, including those used to vigorous activity, can continue during pregnancy and after it.^[6] ACOG adds that very active people can keep doing the same workouts with their doctor's approval.^[3]

For those starting out, the Canadian guideline makes a strong recommendation that previously inactive people become active in pregnancy, beginning gradually and at a lower intensity.^[1] ACOG suggests starting with as little as five minutes a day and adding five minutes each week until you reach 30 minutes.^[3] The NHS suggests starting with around 10 minutes a day, and advises against taking up a new vigorous activity, such as running, during pregnancy.^[7]

The WHO's simplest advice applies to everyone: some activity is better than none, and if you aren't meeting the recommendations yet, start small and build up gradually.^[6] You can track where you are with our pregnancy week calculator, or estimate your dates with the due date calculator.

When should you stop exercising in early pregnancy?

These are the warning signs ACOG lists for stopping exercise at any stage of pregnancy.^[3] The NHS adds a simple rule: stop if you feel uncomfortable, too hot or unwell.^[7] Our guide to warning signs to stop exercising explains each one and what to do next.

As the weeks go on, positions and balance start to matter more. When you reach the second trimester, our guide to exercise in the second and third trimester picks up from here. And for the full picture, see our complete guide to exercise during pregnancy.