Researchers from the Karolinska Institute in Stockholm, Sweden found that the risk of stillbirth and infant death may be raised by mothers’ weight gain between pregnancies.
In the study – published December 2 in the journal the Lancet – the researchers looked at data on about 450,000 women who had been pregnant twice between 1992 and 2012.
They found that women whose weight gain remained stable between pregnancies were 50 percent less likely to have stillbirths, compared with those whose body mass index (BMI) got at least four points higher by the second pregnancy. For a woman who has an average height, four BMI points equates to 24 pounds (11 kilograms).
According to the researchers, women who had a normal body weight in their first pregnancies, or a body mass index less than 25, and who gained 13 to 24 pounds (6 to 11 kilograms) between pregnancies had a 27 to 60 percent higher risk of infant death.
However, among women who were already overweight during their first pregnancies, weight gain between the first and the second pregnancy was not linked to higher risk of stillbirth or infant death. In the study, the researchers define stillbirth as death of the foetus at twenty-eight weeks of pregnancy or later on.
Children of overweight women who lost approximately 13 pounds (6 kilograms) or more between pregnancies, were 50 percent less likely to experience infant death in the first month of their lives, compared with children of overweight women who neither lost, nor gained weight between pregnancies.
The researchers from Sweden said that about 15 percent of the women in the study gained 13 pounds (6 kilograms) or more between the first and second pregnancy. Considerable weight gain before pregnancy needs to be prevented in both healthy and overweight women, and weight loss should be encouraged among overweight women.
Two out of 1,000 women who maintained a stable weight during pregnancy had infant deaths, and two out of 1,000 had stillbirths, the researchers noted. Among those who gained 24 pounds (11 kilograms) or more, three out of 1,000 had infant deaths and four out of 1,000 had stillbirths. Researchers said that overall the numbers were still relatively low.
Although the researchers are not sure exactly why weight gain between pregnancies may lead to higher risk of infant death or stillbirth, it is known that being overweight or obese increases the risk of birth defects and preterm birth.
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