There's no time like the present – as long as your GP or midwife says it's alright. Always warm up and start slowly – don't attempt a 5K for the first time! Swimming may be ideal, especially as your pregnancy progresses. The water supports you and makes you feel lighter. Walking is also fabulous exercise.

Pelvic floor exercises can shorten the intense 'pushing' stage of labour – if you make these easy exercises a habit during pregnancy. Pretend you're stopping yourself from peeing. Squeeze those muscles for a few seconds, then relax. Try to do 3 sets of 8 squeezes each day.

You can do pelvic floor exercises anywhere – sitting in traffic, waiting at the bus stop, even at your desk.

There's room for improvement! According to US research, only one out of six pregnant women say they get moderate exercise – like brisk walking – at least half an hour per day.

What keeps the active women going? Exercise in pregnancy helps you feel better, sleep better and stay within your doctor's weight guidelines. Gaining too much weight can be unhealthy for you and your baby.

If you're a committed runner and you're healthy, you can continue to run while you're expecting. Just be sure to ask your doctor how you should adjust your distance or other routines. Marathon world-record holder Paula Radcliffe ran 14 miles a day while pregnant. Now, however, is not the time to sign up for your first marathon!

A good, supportive bra is going to become your favourite piece of clothing. Your breasts will be sensitive and change in shape and size throughout your pregnancy. The right bra ensures a comfortable workout. Slings or belts for a pregnant belly help some women with back pain in the final stretch, but a good bra will be your best friend for all 40 weeks.

Doctors say that after the first 16 weeks, moves such as crunches that are done while lying on your back are not a great idea. That doesn't mean ignoring your abs. Look for pregnancy-safe core moves, including those done on hands and knees, which can help ease an aching back, too.

Lying on your back after the third month of pregnancy can limit blood flow to the baby and make you feel faint.

You know you're exercising at the right intensity if you recover fully in the time it takes for a tea break: 15-20 minutes. The benefits of your workout will stay with you much longer:  increased energy, a better mood, less stress and less swelling. 

After-baby bonus: It's easier to get back in shape if you've been active during pregnancy.

Stay near the surface of the water! Scuba diving puts your baby at risk of the 'bends', harmful gas bubbles in the baby's blood vessels.

Swimming and water aerobics, on the other hand, are good exercises for pregnant women. They're safe, buoyant ways to get your heart pumping – and the water supports your growing tummy. Snorkeling is fine, too.

Contact sports – where there is a risk of being hit – are not advised when you're expecting. If you collide with someone or fall, it could harm your baby. Other exercises to postpone until after the baby arrives include skiing, gymnastics, cycling and horse-riding as there is a risk of falling. Spin classes and low-impact aerobics are two ways to keep fit without risking a tumble.

No need to worry. For healthy women, exercise does not increase the chances of an early delivery or having an underweight baby.

Salsa and belly dancing are not only safe – they're fun ways to work out when pregnant. You'll find videos and classes to guide your pregnant shape through both types of dance. Dancing is fine in most forms – just keep in mind your changing centre of gravity! 

Stay away from Bikram, a 'hot' yoga. The studio can be over 32°C (90°F), and that may be too hot for your baby. Other kinds of yoga can be great when you're pregnant. The breathing techniques can help you get ready for labour. Also, the poses can help relieve back pain and even morning sickness.

Look for yoga classes designed especially for pregnant women.

It's generally fine to start simple exercises a few days after a vaginal delivery. Be sure you feel up to it. Pushing a pram is an easy start, which may help both you and your new baby relax. Don't stress out about getting back to the gym – those first weeks are exhausting!

With more challenging workouts it’s probably best to wait until after your six-week check-up with your GP or midwife.