Pre-pregnancy kidney function and subsequent adverse pregnancy outcomes.

BACKGROUND

Renal insufficiency is associated with pregnancy complications including fetal growth restriction, preterm birth (PTB), and pre-eclampsia.

OBJECTIVE

To determine the effect of preconception kidney function within the normal range on pregnancy outcome.

METHOD

1043 (50% black, 50% white) women who participated in the CARDIA study who had kidney function and biochemical analyses measured before at least one pregnancy delivered during the 20 years post-baseline period were included in analysis. Kidney function estimated as glomerular filtration rate (eGFR) via modified CKD-EPI equations, serum creatinine, and urinary albumin/creatinine ratio were evaluated as predictors of infant birthweight, gestational age, birthweight-for-gestational-age, and hypertensive disorders of pregnancy via self-report, using multiple regression with adjustment for confounders (age, race, smoking, BMI, center, parity, systolic blood pressure at baseline). Serum uric acid was also examined at both baseline and year 10.

RESULTS

Unadjusted pre-pregnancy eGFR (baseline) was associated with lower average birthweight-for-gestational-age, but this disappeared after adjustment for confounders. A decline in GFR from baseline to year 10 was associated with lower birthweight (adjusted estimate -195 g, p = 0.03 overall), especially among whites. After adjustment for confounders, no association was found with gestational age or hypertensive disorders.

CONCLUSIONS

No strong evidence for an association between preconception kidney function in the normal range and birthweight or gestational age was found. Possible racial differences in these relationships warrant further examination.