Women with morbid obesity with BMI of ≥ 40 kg/m2 or suspected large for gestational age (LGA) fetus or polyhydramnios with normal glucose screening in the second trimester, should be retested for gestational diabetes, suggests a new study published in the March 2023 issue of the Journal of Obstetrics and Gynecology Research.¹

In this study from Israel, researchers analysed pregnancy outcomes of 238 women with normal glucose screening at 24-28 weeks of gestation. Of these 54.6% underwent late repeat oral glucose tolerance tests (OGTT) after 34 weeks due to suspicion of a large for gestational age (LGA) fetus, while 45.4% took a repeat test because of suspected polyhydramnios. The objective of the study was to determine association of maternal obesity with late GDM among women who had had normal OGTT.

The overall rate of late diagnosis of GDM was 22.2%, which climbed up to 33% among women with morbid obesity. The chances of fetal macrosomia, induction of labor due to large-for-gestational-age fetus, neonatal hypoglycemia, jaundice and phototherapy requirement were higher among women with late gestational diabetes compared to those who had normal late OGTT results. A higher pregestational BMI in women diagnosed with late GDM was associated with adverse maternal and fetal outcomes. The outcomes were also compared between women with late trimester GDM and mid-trimester GDM. Again, the risk of macrosomia as well as cesarean section due to macrosomia were higher among women with late gestational diabetes.

Women gain more weight during the later months of pregnancy than in the earlier stages. A normal OGTT screening early in pregnancy may be falsely reassuring. Hence, women with a history of GDM or fasting blood glucose level >95 mg/dL or BMI of ≥ 35 kg/m2 in late third trimester should undergo repeat screening for GDM in later stages of pregnancy after testing negative when screened earlier. Doing so may disclose gestational diabetes and allow appropriate intervention to avoid risks of adverse maternal and perinatal outcomes.

Reference

1. Shqara RA, et al. Third trimester re-screening for gestational diabetes in morbidly obese women despite earlier negative test can reveal risks for obstetrical complications. J Obstet Gynaecol Res. 2023 Mar;49(3):852-862. doi: 10.1111/jog.15515.