Lowering the target blood sugar level for moms with gestational diabetes did not lessen the chance of large newborns, but it did reduce the risk of death or injury to the baby during birth, according to a recent study.

Research led by Caroline Crowther of the University of Auckland, New Zealand, and a team, the findings were published in the journal PLOS Medicine. Gestational diabetes is a significant and growing health problem worldwide, which often causes the birth of especially large babies who face a high risk of obesity and type 2 diabetes later in life. Women can change their diets and take medication to control their blood sugar, but currently, it is unknown how tightly those levels should be controlled to minimise the risks to the mother and baby.

To determine if stricter control is better, researchers conducted a study of 1,100 pregnant women with gestational diabetes seen at 10 hospitals in New Zealand. During the study, each hospital switched from higher to lower blood sugar targets, and outcomes for women and babies in each group were compared.

While tighter blood sugar control did not lead to babies being larger than expected, it did reduce the risk of infant death, trauma, and shoulder dystocia during birth by half. However, tighter control almost doubled the risk of serious health outcomes for the mother, such as a major postpartum haemorrhage, among other complications.

The new results can help doctors decide what blood sugar level individual patients should strive for while managing their gestational diabetes. The study is the largest randomised comparison of two blood sugar level targets reported to date in a diverse population. However, the researchers point out that there is still a need to confirm their findings through additional randomised trials and in different healthcare settings.

Crowther adds, "This unique trial allowed for the sequential implementation of the newly, recommended tighter treatment targets for women with gestational diabetes and assessed if there are true benefits, without harm, to use of tighter treatment targets."