Subclinical postpartum renal structure after hypertensive pregnancy disorders

Abstract

[Abstract] Background: Hypertensive pregnancies are associated with increased risks of renal failure in pregnancy and later life. However, traditional markers of renal function normalize postpartum, making identification of those at future disease risk difficult. We studied whether the type and severity of hypertensive pregnancy associated with postpartum renal structure.

Methods: One hundred and twenty-five women from interventional trials (61 preeclamptic, 33 gestational hypertension, and 31 normotensive pregnancy), aged ≥18 years, were imaged using magnetic resonance imaging 6 to 12 months postpartum. Anthropometric, demographic, blood pressure, and blood sample data were collected during pregnancy and postpartum. Kidney volume indexed to body surface area and corticomedullary differentiation were compared between groups using a 1-way ANCOVA, whereas associations with other outcomes were assessed using correlation tests.

Results: Postpartum total kidney volume indexed to body surface area was smaller in women who had preeclampsia compared with those who had gestational hypertension or a normotensive pregnancy (P=0.049). Total kidney volume postpartum correlated with estimated glomerular filtration rate at delivery (P<0.001). However, smaller volumes were not explained by reduced corticomedullary differentiation, which only differed in women with gestational hypertension compared with preeclamptic (P=0.02) and normotensive women (P=0.007). There were no associations between renal measures and blood pressure during or after pregnancy.

Conclusions: At 6 to 12 months postpartum, preeclamptic women have smaller kidney volumes than women with gestational hypertension or normotensive pregnancies. These smaller volumes relate to lower renal function at delivery but not corticomedullary differentiation, which only differed in women with gestational hypertension.