About half the cases of gestational diabetes, a common pregnancy complication, could be avoided if body weight was maintained in the normal range, according to a study that followed almost two million births in Sweden from 2000 to 2020.

Gestational diabetes, in which a pregnant woman develops high blood sugar levels, can increase the risk of type 2 diabetes later in life. Obesity and overweight, indicated by a higher-than-30 body mass index, have been studied to have adverse pregnancy outcomes.

In this study, researchers at Linköping University, Sweden, estimated the extent to which pregnancy complications could be averted if women had normal weight before conceiving.

Healthy weight before pregnancy

"For example, we concluded that about half of all cases of gestational diabetes could potentially be prevented. This applies to both women born in Sweden and foreign-born women," Maryam Shirvanifar, a PhD student at Linköping University and first author of the study published in The Lancet Public Health journal, said.

The researchers also found that over a quarter of pre-eclampsia cases could be avoided if a healthy weight is maintained prior to pregnancy. The condition involves high blood pressure and can be accompanied with severe headaches, vision problems such as blurring, and swelling in feet and ankles, among others.

The study looked at both women born in Sweden and those who had moved to the country from regions around the world, including Europe, Latin America and South Asia.

Efforts to promote a healthy weight could be beneficial to all women, regardless of ethnicity, according to lead researcher Pontus Henriksson, a senior associate professor at the Department of Health, Medicine and Caring Sciences at Linköping University.

"A healthy weight is good for everyone. The earlier in life the better, because once obesity is established, it is difficult to treat," Henriksson said.

Further about the study

Of the nearly two million pregnant women studied, close to 17,000 were born in South Asia.

"The number of cases of gestational diabetes attributable to overweight and obesity was about four times higher for women born in South Asia, sub-Saharan Africa, and North Africa and the Middle East than for Swedish-born women, which is probably due to a higher prevalence of gestational diabetes in the former birth regions," the authors wrote.

Some of the other complications the researchers looked at included infant death in the first year of life, premature births and unusual baby sizes at birth. They took data from national registers to analyse the relationship between a woman's body mass index prior to pregnancy and complications depending on which region of the world she was born in.

"Promotion of a healthy weight in pregnancy has the potential to reduce the burden of adverse pregnancy outcomes and possibly reduce inequalities in reproductive health," the authors wrote.