Weight gain between pregnancies risky

London: Women who gain weight between pregnancies raise their risk of suffering from complications such as high blood pressure, diabetes and stillbirth, researchers said on Friday.

Even mothers who are not overweight or obese but who increase their weight before their next pregnancy could be more likely to encounter problems.

"Weight gain increases the risk of a number of pregnancy complications and this further indicates that previously reported associations between obesity and pregnancy outcomes are causal," said Professor Sven Cnattingius, of the Karolinska Institute in Stockholm in Sweden.

In a study that looked at a population of more than 150,000 women in Sweden who had their first and second children between 1992 and 2001, Cnattingius and Eduardo Villamor of the Harvard School of Public Health in Boston, Massachusetts studied the association between interpregnancy weight gain and complications during pregnancy and delivery.

They found that the more weight the women gained between births, the higher their risks were for pre-eclampsia.

Pre-eclampsia is a complication that occurs in about 5 per cent of pregnancies- hypertension, diabetes, caesarean section, stillbirth and the delivery of a large baby.

"It turns out that women do not need to become overweight or obese in order to increase their chances of having poor gestational outcomes; only a relatively modest increase in weight between pregnancies could lead to serious illnesses," Villamor said in a statement.

However, if women lowered their weight, the risks decreased.

In the study published in The Lancet medical journal, the scientists calculated the difference in the women's body mass index (BMI) at the first and second pregnancies and the rate of complications during the second pregnancy and birth.

BMI is calculated by dividing weight in kilograms by height in metres squared. A BMI of 20-25 is healthy. From 25-30 is overweight and 30-40 is obese.

Although the baseline risk of suffering most of the complications was less than one percent, a gain of one to two BMI units increased the odds of diabetes and high blood pressure during pregnancy an average of 20 to 40 per cent. One BMI unit is 6.6 pounds (3 kg).

If a woman gained three or more BMI units, it was associated with a 63 percent greater chance of stillbirth compared to a gain of less than one BMI.

"My advice to women is to try to avoid gaining weight between pregnancies," Cnattingius said.