The effect of diabetes during pregnancy on fetal renal parenchymal growth.

Aims/hypothesis: Diabetes in pregnancy is thought to adversely affect the developing fetal kidneys. The rate of gestational diabetes is increasing globally with major consequences for future renal function. Very little is known about the impact of hyperglycaemia on the fetal renal parenchyma which contains the developing nephrons. The aim of this study was to measure the fetal renal parenchymal thickness and evaluate whether diabetes during pregnancy affects the growth of the fetal kidneys.

Methods: This prospective, observational study used serial ultrasound measurements to evaluate the fetal renal parenchymal growth of 55 pregnancies with diabetes compared to 72 control pregnancies. Mixed effects modelling was used to analyse the data.

Results: The renal parenchyma of fetuses from mothers with gestational diabetes was significantly thicker than those from the control group (LR Chisq = 4.8, df = 1, p = 0.029), however, the difference was proportional to the larger size of these fetuses. Fetuses of pregestational diabetics demonstrated no significant difference in renal parenchymal thickness compared to the control group even though they were also larger fetuses. Parenchymal growth slowed with increasing abdominal circumference in the pregestational diabetic group, suggesting an adverse effect on nephrogenesis, however this did not reach statistical significance.

Conclusions/interpretation: Our study provides unique data on how diabetes during pregnancy influences fetal kidney growth. Appropriate management of diabetic pregnancies may mitigate some of the adverse effects on the fetal kidneys. Increasing degrees of hyperglycaemia, as seen sometimes in pregestational diabetes, may affect nephrogenesis; however larger studies are needed.