Researchers study gestational diabetes mellitus and its association with maternal and fetal outcomes

Gestational diabetes mellitus (GDM) is a chronic disease and the most common health complication associated with pregnancy, affecting many millions of women worldwide. The number of pregnant women being diagnosed with DG is increasing and it is thought to be associated with the rising incidence of obesity worldwide.

In a recent systematic review published in the BMJ journal, researchers quantify outcomes of pregnancies complicated by GDM.

Study: Gestational diabetes mellitus and adverse pregnancy outcomes: systematic review and meta-analysis. Image Credit: Doro Guzenda/


The 2008 HAPO (Hyperglycemia and Adverse Pregnancy Outcome) study defined the risks associated with adverse effects related to hyperglycemia. Here, maternal hyperglycemia was found to independently increase the risk of preterm birth, cesarean delivery, large-for-gestational-age infants, admission to a neonatal intensive care unit (NICU) , neonatal hypoglycemia and hyperbilirubinemia.

Despite these results, the HAPO study did not adjust for major confounding variables, such as maternal body mass index (BMI). In addition to a lack of data on rates of stillbirth and neonatal respiratory distress syndrome, the HAPO study also failed to provide clear reports of preterm birth, neonatal death, and low score. Apgar in infants born to mothers with DG in their large cohort.

About the study

A total of 44,993 studies were identified for the current review, of which 156 were included in the final analysis. Together, data from more than seven million women were analyzed for the current meta-analysis.

Of the included studies, neonatal outcomes were reported in 151 studies, while maternal outcomes were reported in 133 studies. Most of the studies included in this meta-analysis were conducted in Asia, Europe and North America.

Consistent with the Newcastle-Ottawa Scale, 50 of the 156 included studies were at low or medium risk of bias, while 106 were at high risk of bias. In 35 of the included studies, patients had never received insulin therapy during their GD. In comparison, patients in 63 of the studies received insulin therapy in varying proportions. The remaining 58 studies reported no data on insulin use.

Thus, each study was classified into the following categories: no insulin use, insulin use, or insulin use not reported.

Study results

Studies in the insulin-free group found that women with DG had an increased risk of preterm birth and caesarean section, as well as giving birth to infants with macrosomia, low Apgar score at one minute and large for their gestational age. In addition, a strong association was observed between the number of GDM patients who received insulin and the estimated effect size of adverse outcomes, including caesarean section and preterm birth.

In studies of insulin use, after adjusting for confounders, the likelihood that a baby will be born large for gestational age, have respiratory distress syndrome or neonatal jaundice, or require admission in NICU was higher in women with GDM than in those without.

Women with DG in studies that did not report insulin use were associated with an increased risk of induction of labor, premature rupture of membranes, preeclampsia, cesarean section, and preterm delivery. Infants born to these mothers also had an increased risk of macrosomia, birth defects, neonatal hypoglycemia, and NICU admission.

Overall, no significant association was identified between GDM and mortality events. Although there was an increased incidence of neonatal death in infants born to mothers with DG, its incidence was low at 3.75%. Some of the potential mechanisms that may increase the risks of neonatal death from GDM could include respiratory distress syndrome, neonatal hypoglycemia, and jaundice, all of which can increase the likelihood of an infant being admitted to NICU.


The results of the current study provide an updated review of the adverse effects associated with DG in pregnancy. Taken together, these findings can be used to counsel and educate women diagnosed with gestational diabetes before they give birth.

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