I'm four months pregnant but I'm keen to keep running for as long as possible. Should I go on how I feel or is there a sensible time to stop?

Health bodies recommend two and a half hours of moderate exercise per week during pregnancy, and evidence suggests that this will increase your chances of a healthy term, a healthy baby and a good recovery after birth. Further regular exercise can reduce the chances of diabetes and high blood pressure, while improving your mood, strength, physical capacity and possibly the birth weight of your baby. Your birth may also be less complicated.

So can you run to achieve this? If you are a regular runner then yes, but if not then start with walking. Either way, exercise needs to be moderate. High intensity and prolonged exercise such as racing, running for more than 40 minutes and exhaustive training can all, in theory, stress blood flow to the baby and raise the body temperature excessively, which has potential consequences of premature labour and bleeding.

If you are intending to run, make sure you warm up properly and start out steadily. After your first trimester – ie from three to four months onwards – your body shape will be changing, putting extra strain on your back, pelvis and joints. Furthermore, your cardiovascular system will have to cope with the extra load. Therefore, consider switching to lower-impact exercise such as power walking, static cycling, cross-training, low-impact aerobics and swimming, and avoid weights and activities that dictate you need to lie on your back.

Pregnancy can become complicated so you should check with your doctor that your circumstances are suited to running. A starting point for advice can also be found from the American College of Obstetricians and Gynaecologists.