Diabetes in pregnancy – gestational diabetes mellitus – is associated with increased risk of health complications for both mother and baby, including caesarean delivery, severe breathing problems, and excessive birth weight. Gestational diabetes develops when the mother’s body can’t produce sufficient insulin to control blood sugar levels during pregnancy.
Researchers at Central South University in China analysed data from 156 studies involving more than seven million participants that reported complications of pregnancy in women with gestational diabetes.
Studies were adjusted to take account of at least one of seven confounding factors:
To assess the effect of different severities of gestational diabetes, the researchers categorised studies by insulin use – considered standard treatment for gestational diabetes when adequate blood sugar levels are not achieved with diet and exercise.
Analyses were then performed based on study country – developed or developing – quality of the study, diagnostic criteria, and screening method used.
In studies with no insulin use, when adjusted for confounders, they found that women with gestational diabetes had increased odds of caesarean section, preterm delivery, low one minute Apgar score – a measure of an infant’s condition at birth – excessive birth weight, and infant born large for gestational age than those without diabetes.
In studies with insulin use, when adjusted for confounders, they found the odds of having an infant large for gestational age, or with respiratory distress syndrome, neonatal jaundice, or requiring admission to the neonatal intensive care unit were higher in women with gestational diabetes than in those without diabetes.
They found no clear differences in the odds of several other outcomes, including instrumental delivery (e.g., forceps), postpartum haemorrhage, stillbirth, neonatal death, and low birth weight between women with and without gestational diabetes, after adjusting for confounders.
These are observational findings, so can’t establish cause, and the researchers cannot rule out the possibility that other unmeasured factors may have affected their results. Differences in study definitions of diabetes and some pregnancy outcomes may also have had an impact.
Nevertheless, this is the most in-depth analysis of its kind to date, which the researchers said: “contribute to a more comprehensive understanding of adverse outcomes of pregnancy related to gestational diabetes mellitus. These findings support the need for an improved understanding of the pathophysiology of gestational diabetes mellitus to inform the prediction of risk and for precautions to be taken to reduce adverse outcomes of pregnancy.”