I'm pregnant and getting conflicting advice about whether or not it is safe to exercise. I was fit before, so it feels alien not to exercise now.

For many years, the consensus was against exercising while pregnant. However, in 2002 the American College of Obstetricians and Gynecologists stated that in the absence of contra-indications (risk of pre-term labour, bleeding after the first four months of pregnancy, or history of lung disease or an unstable heart), pregnant women should be encouraged to engage in regular moderate-intensity exercise.

Exercise has a hugely positive role to play in pregnancy and labour, improving body image and overall wellbeing at a time when it can feel as if your body is out of control. Pregnancy is not a disease and with few exceptions (avoid scuba-diving, high-altitude activities and those that carry a risk of a fall or of abdominal discomfort), most women do not need to change what they are doing because they are pregnant. If you are currently sedentary, try moderate, low-impact activity such as swimming or brisk walking, three times a week for 30 minutes. If you're a regular exerciser, three to five sessions a week of moderately hard-exertion, low-impact exercise for 30-60 minutes is acceptable. And if you're an elite athlete, aim for four to six sessions a week, 60-90 minutes in duration, at 70-80% of maximum heart rate.

Check with your GP first and do listen to your body as you exercise. Stop immediately if you experience vaginal bleeding, dizziness, chest pain, muscle weakness, calf pain, swelling or uterine contractions.

Joanna Hall is a fitness expert (joannahall.com). Send your exercise questions to Weekend, 119 Farringdon Road, London EC1R 3ER (weekend@theguardian.com).