Pregnant? Then you'll need some exercise

Getting fitter as you get bigger brings a bundle of benefits before the birth, says Gavanndra Hodge. And as a bonus, it will help you slim down afterwards, too

Many women regard preg-nancy as the ultimate excuse to throw away their trainers and embark on a dedicated campaign of sitting on the sofa eating chocolate. Any flickers of guilt will have been extinguished last month when the results of a study conducted at Southampton University on the effects of exercise during pregnancy were announced. These indicate that women who take part in excessive physical exercise in late pregnancy increase the risk of their babies growing up to develop the bone disease osteoporosis.

"If they undertook heavy weight-bearing activity in late pregnancy, the bone-mineral content of their baby was around eight per cent lower," said Professor Cyrus Cooper, who headed the research, in which 150 pregnant women took part. But this is no excuse for pregnant women to stop exercising altogether. Although shifting pianos in the very last weeks of pregnancy may be harmful, keeping fit, particularly during the first two trimesters, is undoubtedly beneficial.

Studies indicate that pregnant women who exercise sensibly tend to have babies on the smaller side of the healthy range, making post-partum recovery quicker, and they find it much easier to regain their figure (women tend to put on between 25 to 35lb during pregnancy, and it usually takes about six months for the body to return to normal). There is also some evidence that exercising while pregnant results in a shorter labour.

Exercise can also relieve morning sickness, help regulate sleeping patterns and improve mood. As the pregnancy progresses increased pressure is put on the spine, and the lower abdominal area is stretched and strained. Exercise mobilises and strengthens the spine, lessening back pain, and also fortifies the abdominal muscles. Labour itself demands prolonged physical exertion, and women who have built up their strength, stamina and cardiovascular fitness will find the ordeal much easier.

However, there are a number of important precautions to bear in mind before embarking on a fitness regime. Women who were active before their pregnancy should continue, but with a lighter regime, while those who did no exercise previously should take the advice of a doctor or midwife.

Pregnant women have less oxygen available for aerobic exercise, and therefore should stick to 60 per cent of their maximum heart-rate, making sure their average heart-rate does not exceed 140 beats per minute. They should never exercise to the point of breathlessness, as this could indicate that they and the baby are not getting enough oxygen.

During the second and third trimester, women should avoid exercises that involve lying flat for more than two minutes, because the weight of the baby presses on the vein that returns blood to the mother's heart, and the danger is that the supply of nutrients and oxygen to the baby could be restricted.

It goes without saying that sports that present any risk of abdominal injury – polo, downhill skiing and most contact sports – should be avoided. The first 14 to 16 weeks of pregnancy is the time most women are vulnerable to miscarriage. For that period, pregnant women should not take part in sports where there is the potential for sudden shocks, such as horse-riding or squash. Finally, the body requires more fluid during pregnancy, so be sure to keep hydrated.

However, exercise is not safe for all pregnant women. Women who have experienced obstetrical complications, or have a history of medical problems such as high blood pressure, diabetes, heart disease and thyroid disease, should only exercise with their doctor's approval.

Yoga

Recommended by midwives and fitness professionals alike. The deep-breathing method taught in yoga increases the intake of oxygen by up to a third, and hence increases the supply of oxygen to the developing foetus. A pregnant woman's body releases more of the hormone relaxin, which promotes flexibility (this also means that pregnant women should be careful to stretch thoroughly before and after exercising, as loose joints make them more vulnerable to injury). "Yoga helps the pregnant woman hold herself better and breathe properly, making pregnancy more comfortable and labour easier," says Jessica James, a yoga teacher who specialises in instructing pregnant women. "But it is very important that they go to a proper pre-natal yoga class. It would be a very bad idea, particularly for someone who has never done it before, to go to something like an Astanga class."

Pilates

Another very beneficial exercise that strengthens the abdominal muscles, improves mobility and can be done right up to the birth of the child. However, some of the mat-based exercises are not suitable for pregnant women. "It is essential that you warn the teacher of your condition before the start of the class," says pilates teacher Noel Butler.

Swimming

Works both large muscle groups – the arms and legs – and the water supports your weight. Importantly, there is little threat of overheating. Exercise increases body temperature. Some studies have shown that fevers during the first trimester can affect the development of the baby. It is not a good idea to dive in the later months of pregnancy, though.

Gyrotonics

This is an exercise based on yoga, tai chi and dance that was devised in the Eighties. It is designed to lengthen and strengthen abdominal muscles, stimulate the nervous system and cleanse organs and glands. Very popular in America, and increasingly available in this country.

Running

Numerous studies have been done on the safety of running while pregnant, and the results are reassuring. The Melpomene Institute completed a study on 195 pregnant women who were averaging 24.8 miles a week three months before conception. All the babies were born healthy, with an average weight of 6lb 7oz. If you feel Braxton Hicks contractions (contractions of the lower abdomen) stop running and walk until they stop. It is recommended to cut back your running by about 40 per cent during the second trimester and 70 per cent during the third.

Abdominal exercises

The abdominal muscles support the whole body. The stronger they are the more stress they can take. Also, because blood supply to a developed muscle is greater than that toward an untoned one, a toned abdomen will repair faster. During pregnancy it is best to concentrate on stomach exercises that engage the traversus abdominus, the deepest layer of muscle. This will help stop the spine arching.

For details of yoga teachers who specialise in classes for pregnant women, visit www.activebirthcentre.com, or call 020 7482 5554. Accredited pilates teachers can be found at www.pilates.co.uk. Fitness kit is available from www.mothers-in-motion.com. The National Register of Personal Trainers, 0208 944 6688, can provide trainers who specialise in fitness for the pregnant.