Histomorphological changes of the placenta and umbilical cord in pregnancies complicated by gestational diabetes mellitus

The objective of this study was to compare the histomorphological changes of placenta and umbilical cord (UC), between gestational diabetes mellitus (GDM) and non- GDM pregnancies. In this prospective study, 222 parturients were recruited (117 GDM and 105 non-GDM). GDM was confirmed at 24–28 weeks of gestation, using one-step strategy. A full record of demographic, laboratory, histologic and gross morphology data of placenta and UC was extracted and analyzed. Overall, 222 placentas/UCs met inclusion criteria. The mean (SD) of gestational age of GDM diagnosis was 20.68 (10.02) and the GDM duration was 16.76 (8.98) weeks. The mean HbA1C was 6.03 (0.41) % in the GDM group. The gross morphology findings including UC diameter and thick edematous UC differed significantly between two groups and more presented in GDM group, 1.41 (0.03) vs. 1.28 (0.03) centimeters; p-value = 0.006 and 34.19% vs. 16.19%; p-value = 0.002, respectively. The umbilical coiling index (UCI) was similar in two groups (p-value = 0.61). In the histological evaluation, persistence of central vessels differed significantly between two groups, more detected in non-GDM (47.62% vs. 32.97%; p-value = 0.04). No other significant histomorphological changes were detected between two groups. This study showed that gross morphologic features such as UC diameter increment and thick edematous UC happened more frequently, among the GDM parturients. Due to early diagnosis, diagnosis strategy, and optimal glycemic control, the histomorphological changes were less in GDM comparing of non-GDM group. •GDM could induce the histomorphological changes of placenta and umbilical cord.•The histomorphological changes depends on GDM duration and its glycemic control.•The histomorphological changes in GDM are inconsistent and somewhat controversial.•This longitudinal study allowed us to follow the prenatal and postnatal period.•The study population comprised GDM and normal pregnancy, providing valid comparison.