Staying fit and healthy by doing regular exercise can be one of the best things you can do during pregnancy, helping to strengthen and prepare your body for the next nine months, and the labour and birth at the end of this period.
Dr Jo Mountfield, consultant obstetrician and vice president of the, says: 'It is important to stay active and to eat well during pregnancy. Maintaining a good level of exercise and physical activity that is usual for you can help the body adapt to the changes brought on by pregnancy.'
There's no evidence of harm to you or your baby from taking moderate intensity physical activity (defined as being an activity that makes you feel warmer and breathe faster but still allows you to hold a conversation), and there are a number of benefits.
High blood pressure in pregnancy – whether it's pre-existing or comes on in pregnancy – can increase the incidence of complications such as stillbirth. Not only that, but NICE (National Institute for Health and Care Excellence) says that women with hypertension in pregnancy are also at increased risk of cardiovascular disease later in life.
A 2022 US study, reported in the journal AJOG Global Reports, says that 10% of all pregnancies are complicated by a high blood pressure disorder of pregnancy.
The same study found that all exercise types – resistance, aerobic, and aerobic combined with resistance – were beneficial in lowering a mum-to-be's resting blood pressure throughout pregnancy.
Fitness isn't just about the parts of your body you can see – it's about your internal organs, too, including your heart and lungs.
During pregnancy, a pregnant woman's blood volume increases by an average of 45%, which means the heart and lungs have to work harder than usual. Being physically active helps to keep these organs in good shape.
Research from 2020 published in the journal Asian Nursing Research suggests that 76% of pregnant women experience poor quality sleep throughout all trimesters, and that sleep disturbances have been linked to increased risk of several problems in pregnancy, including emergency caesarean sections, pre-term birth and development of depressive symptoms.
The same meta-analysis of seven studies indicated that exercise can contribute to pregnant women getting better quality sleep.
A study of 15.8m US pregnancies by researchers at Wuhan University, published in the journal JAMA Network Open, concluded that expectant mothers shouldn't gain more than 24kg (52lb) if they have a normal or underweight body mass index (BMI) and between 8-16kg (18-35lb) if they are mildly obese.
However, the research also recommended that even women with higher BMIs should not be encouraged to lose weight or even maintain it while pregnant but to try to gain less, and that exercise and nutrition could help with this.
Gaining too little weight in pregnancy can also be problematic, increasing the risk of a premature birth, but some women who are naturally slim stay that way when pregnant and go on to have healthy babies.
Some women are at risk of gestational (pregnancy) diabetes, where high blood sugar develops during pregnancy because your body can't produce enough insulin to control the glucose levels. This can lead to increased problems during pregnancy, such as pre-eclampsia.
Exercise has been found to decrease the risk of gestational diabetes. When you exercise, your muscles take up the glucose from your bloodstream, helping to reduce levels of it in the blood, as well as helping your muscles to remain more receptive to the effects of insulin – even after you've stopped exercising.
Exercise and activity lead your body to produce endorphins, which are hormones that are linked to lowered levels of anxiety and depression.
Pregnancy charity Tommy's says: 'When you're pregnant, your body is more sensitive to endorphins, so activity can boost your mood for longer.'
Experts recommend that you should be aiming for at least 150 minutes of moderate intensity activity spread throughout the week in bouts of at least 10 minutes. The easiest way may be to think about it as doing 25 minutes of exercise six days a week with one day off if needed.
Dr Mountfield says: 'If you were not active before pregnancy, it is important to start gradually and only do exercise for as long as feels comfortable.' In this instance you should start with no more than 15 minutes of continuous exercise three times a week, gradually increasing to longer daily sessions.
If you are already active, you can continue what you are doing, as long as you adapt your activity if it's not recommended, or if it becomes necessary later as your pregnancy progresses.
Activity – which can be out and about, at home or at leisure facilities – should be a mixture of aerobic, strength and stability, including:
You don't have to do organised exercise unless you want to. The main rule is to be as active as possible – how you do it is up to you.
Whatever it is, any activity that warms you up, makes you feel a bit out of breath and lasts at least 10 minutes counts towards your total.
When you're thinking about what activities to do, don't forget stomach strengthening exercises (to strengthen your abdominal muscles and help to guard against pregnancy backache) and those for your pelvic floor,
Dr Mountfield says: 'We'd encourage pregnant women to also do pelvic floor exercises regularly to help strengthen these muscles. During pregnancy, pelvic floor muscles are put under strain, and these exercises can help with labour and aid recovery after birth.'
Some forms of gym-style exercise equipment are safe to use during pregnancy, including stair climbers, treadmills, ellipticals and rowing machines, as well as weight machines.
There are also those you can buy to use at home, including resistance bands and free weights, as well as a birthing ball, which you can also use when you're in labour.
The important thing with gym machines is to adjust the speed, tension and incline to a comfortable level, as well as paying close attention to where you are stepping so that you don't stumble.
When it comes to free weights, there isn't specific guidance about which ones you should use but it's best to use weights that feel light to moderate to you, rather than heavy. Tommy's says: 'A good rule of thumb is that you should do more repetitions with lighter weights.'
It is best to speak to an instructor or a member of staff at the gym before you start any exercises when pregnant, so they can advise you of what is safe to use and what you should avoid.
Yes, it's safe to exercise throughout pregnancy (although do follow your doctor or midwife's advice if you're one of a small group who may have issues – see below).
The first trimester can be one of the hardest for women, either because they're suffering with sickness, or because of extreme tiredness. If that's the case, opt for gentle exercise such as a walk, swimming or yoga.
It may seem hard to believe, but activity can actually boost energy levels, especially if it's outdoors.
However, don't beat yourself up if you can't maintain the levels of activity you had before you got pregnant, or find just getting out of bed each day is a struggle. Energy levels usually return by the second trimester.
The Royal College of Nursing says: 'There are very few absolute contraindications to exercise during pregnancy and these are mostly related to the pregnancy itself, eg risk of premature labour or presence of pre-eclampsia.'
Some of the contraindications include those with persistent bleeding in the second or third trimester.
Generally, if you have an uncomplicated pregnancy, you're encouraged to keep active during pregnancy. However, Dr Mountfield says: 'Anyone who has any concerns about exercising whilst pregnant should speak to their doctor or midwife.'
If you are exercising and start to feel dizziness, headache, chest pain, muscle weakness affecting balance, calf pain or swelling, vaginal bleeding, regular painful contractions or amniotic fluid leakage then stop immediately.
These include football, rugby, hockey, squash or martial arts such as judo or kickboxing. This is because there's a risk of your bump being hit.
Tommy's says that exercise or activity where there's a risk of falling, such as skiing, horse riding or climbing, can be risky because your centre of gravity will be altered as your bump grows, making it harder to keep your balance.
The NHS says you shouldn't exercise at altitudes of more than 2,500 metres above sea level because you and your baby are at risk of altitude sickness.
Certain types of yoga are great for pregnancy but hot yoga – which takes place in a room heated to as much as 42°C – might cause overheating. Take care if exercising during hot weather, too, and remember to keep well hydrated.
This is not safe during pregnancy because nitrogen gas bubbles can travel across the placenta, and your baby doesn't have any protection against decompression sickness and gas embolism (gas bubbles in the bloodstream).
For example, you should avoid certain exercises or positions, such as those that require you to lie on your back after 16 weeks because the weight of your baby on key blood vessels could reduce blood flow to your heart – and therefore your baby. Weighted sit-up exercises should be avoided after 12 weeks.
Although light weights can be safe to use in pregnancy, there are certain other kinds that aren't. Cross-fit type training (using heavy weights in a timed circuit), general circuit classes using fast movements and bar bells, exercises using heavy bar bells behind your neck after 12 weeks (it's best to use dumbbells instead) and deadlifts using a large barbell should be avoided.