Exercise and fitness Heather Welford Exercise boosts your immune system and provides the circulation and energy levels needed to help you conceive, enjoy your pregnancy and prepare your body for labour.

In this article

Exercises to avoid

Enjoyable activities

Your pelvic floor

You don't have to be an Olympic athlete, but it's important you're able to climb stairs comfortably and lift reasonable weights, such as a sleeping child. Women gain an average of two stone during pregnancy, so your muscles and posture are going to be seriously overworked and under strain - even before you go through childbirth.

The good news is that the better your cardiovascular system (heart and lungs), the more stamina you'll have for the birth.

Exercise also helps with:

• Constipation
• Backache
• Fatigue
• Varicose veins
• Circulation problems
• Meeting other mums-to-be

Contact sports are best avoided, as are activities involving heights. And scuba diving isn't recommended, as no one knows what effect it can have on your pregnancy or baby.

Anything that puts a strain on your joints or ligaments - such as high-impact aerobics, difficult yoga positions or jogging on the road - should be done more gently.

There's a higher risk of strains during pregnancy because hormones are released to loosen your joints and ligaments in preparation for the birth, when your pelvis needs to open to allow your baby to be born.

Activities such as brisk walking, swimming, and gentle toning and stretching classes are ideal during pregnancy.

Cycling is good exercise, too. As you get bigger, you'll find you have to get used to the changes in the distribution of your weight, and you may need to adjust your saddle and handle bars. In late pregnancy, it's safer to use an exercise bike, in case you fall.

If you were already attending an exercise class before your pregnancy, tell your instructor you're pregnant. They'll be able to advise you on any parts of the class that are now unsuitable.

Water baby

Exercising in water is safe and enjoyable during pregnancy - and it's great for late pregnancy backache. The water supports your whole body, and you can be as energetic or relaxed as you want. Many public and private pools offer antenatal classes, often run by trained midwives or physiotherapists. Swimming several lengths gives you a good, safe workout.

The pelvic floor is formed of layers of muscle that support the uterus, bowel and bladder. Pregnancy and childbirth put pressure on these muscles, and you may find that you urinate slightly when you sneeze or cough - this is called 'stress incontinence'.

You can tone these muscles so they maintain their strength - and regain it quicker after the birth - by doing regular 'invisible' exercises.

Pull in and tense your pelvic floor muscles, as if stopping the flow of urine. Hold for five seconds, then relax. Aim to do ten sets of five exercises each day, although don't do them while you're actually urinating.

Disclaimer: The BBC Parenting site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. The BBC is not responsible or liable for the contents of any websites of third parties which are listed on this site.