That’s the conclusion of a study of 150,000 Swedish mothers, presented in the medical journal The Lancet this week.
It has long been known that obesity increases the risk of toxaemia, or pre-eclampsia, and high blood pressure.
But the new research shows that just a few kilos’ weight gain between pregnancies increases the risk of other complications – even among mothers of a normal weight.
For the group of women whose weight increases by nine kilos or more, the danger was greatest. Indeed, the research showed that the risk of pre-eclampsia and high blood pressure rose by 80 percent, while the risk of stillbirth went up by 60 percent.
But the risk of complications increased after a weight gain of only three kilos. An rise of between three and six kilos increased the risk of high blood pressure, pregnancy diabetes and overweight children by 20 to 40 percent.
“What we found was that the amount of the weight increase really didn’t matter,” said Sven Cnattingius, professor at the Karolinska Institute who carried out the study with the Harvard School of Public Health.
“Our results ought to serve as the basis for proposing weight loss to overweight women who plan to get pregnant, but above all, when it comes to preventing women of a normal weight from increasing between pregnancies.”