Pregnancy weight gain linked to stillbirths

03 December 2015
University of Auckland, Head of Department of Obstetrics and Gynaecology, Professor Lesley McCowan
University of Auckland, Head of Department of Obstetrics and Gynaecology, Professor Lesley McCowan

Better awareness of the importance of healthy diets and physical activity for the ideal weight in pregnancy may be an important strategy to reduce the risk of stillbirths and infant deaths, according to University of Auckland researchers.


In a Lancet editorial published today Professor Lesley McCowan, Head of Obstetrics and Gynaecology at the University and Dr Chris McKinlay, a neonatal paediatrician from the Liggins Institute, say that “We need effective fiscal and public health strategies to improve the awareness and implementation of the benefits of healthy diets and physical activity in young people.”


“In turn this improvement would reduce obesity and excessive pregnancy weight gain in pregnant women, mitigate postpartum weight retention, and potentially reduce stillbirth and infant death.”


They were commenting on research published in the same issue of the Lancet that shows weight gain between pregnancies (even in healthy weight women) increases the risk of stillbirth and infant death.


That research involving more than 450,000 Swedish women, (led by Professor Sven Cnattingius from the Karolinska Institute in Stockholm and Professor Eduardo Villamor from the University of Michigan, School of Public Health), revealed an incremental increase in the risk of stillbirth with weight gain between pregnancies.


Babies of mothers who gained more than four BMI units (around 11 kg in Swedish women of average height) between first and second pregnancies had about a 50 percent greater risk of stillbirth than babies whose mothers had weight between pregnancies (BMI change from -1 to less than 1 kg/m²).


Importantly, among women of healthy weight during their first pregnancy who gained even a moderate amount of weight (around six kg in a woman of average height) by their second pregnancy there was a 30 percent increase in the risk of their baby dying in its first year of life.


The risk was even greater in those women who gained more weight between pregnancies.


Overweight women who lost only a modest amount of weight (around seven kg or more) before a second pregnancy had a 50 percent reduction in the risk of their baby dying in the first month of life.


Professor McCowan and colleagues highlighted that progress in reducing stillbirth rates was poor, but that weight gain between pregnancies might be an important “modifiable target to reduce stillbirth and neonatal death substantively.”


“This may be important for mums too as retention of weight after pregnancy is a major risk factor for obesity in women,” she says.


“We need better information on why some women regain their pre-pregnancy weight and others do not. Excessive weight gain in pregnancy may not be the only factor,” says Professor McCowan. “We know that a mother’s life after birth is both physically and mentally challenging.”


“The benefits of preventing weight gain between pregnancies may be even more important in New Zealand where rates of stillbirth are higher than in Sweden”, she says.


“While the risk for an individual woman is low the potential impact for a population, of these findings is significant.”


Professor McCowan, Dr McKinlay and a team of researchers in South Auckland are actively looking at ways to achieve healthy weight in pregnant women, particularly in women who start pregnancy already overweight or obese.


“This problem has reached epidemic levels with more than 40 percent of mothers in South Auckland overweight or obese,” says Professor McCowan.


They are conducting the HUMBA (Healthy Mums and Babies) trial of dietary education and probiotics in overweight women in South Auckland with the aim of reducing pregnancy weight gain. If HUMBA is successful it could also reduce weight gain between pregnancies (