Workout warning to women

Pregnant women who refuse to ease back in the gym are warned today that they risk having smaller babies.

New research suggests working out vigorously while pregnant can seriously damage foetal growth, and that babies of women who continue with activities such as weight-training are at significant risk of being affected.

Childbirth charities say modern-mothers, under intense pressure not to lose their figures, take unnecessary risks to keep fit. The findings follow an American study, which examined the effect of exercise on the development of unborn babies.

Volunteer mothers-to-be were divided into groups and given different exercise programmes, which they followed from the eighth week of pregnancy until the birth. Their babies were then weighed and measured.

The babies of those assigned to a high volume of exercise in mid-to-late pregnancy were significantly lighter and thinner than those born to women who eased off their fitness programme. Women who continued to use weights and take part in aerobic exercise late into their pregnancies gave birth to babies weighing an average 7lb5oz, with 8.3 per cent of body fat, while babies whose mothers gave up intensive workouts weighed an average of 8lb7oz, with 12.1 per cent body fat.

Professor James Clapp, who led the research at Case Western Reserve University in Ohio, said: "These findings indicate that a high volume of moderate intensity, weight-bearing exercise in mid and late pregnancy reduces foetal growth. A reduction in exercise enhances growth, with a proportionately greater increase in fat mass than in lean body mass."

The findings will concern women eager to follow in the footsteps of celebrity mothers such as Madonna and Catherine Zeta- Jones, who famously regained their figures within weeks of giving birth.

Previous research has suggested that regular vigorous exercise such as aerobics in the first six months of pregnancy has significant positive health effects, including cutting the risk of premature birth by up to 50 per cent.

Other studies have indicated that women who exercise during pregnancy lose weight more quickly after the birth, and enjoy improved mood and sleep patterns.

Melinda Nicci, a London- based personal trainer who specialises in exercise programmes for pregnant women and new mothers, said: "It is all about getting a realistic balance.

"If a woman is in good condition, then she can exercise vigorously quite safely late into the pregnancy, as long as she is careful about risks such as dehydration. I do not believe it is dangerous.

"But if a pregnant women is not that fit, she should not overdo it."