Kidney disorders associated with adverse birth outcomes across conception methods

A population-based retrospective study in Human Reproduction examined conception methods and perinatal outcomes in New South Wales and the Australian Capital Territory between 2009 and 2017. Researchers linked perinatal, hospital, assisted reproduction and national claims records for 911,229 babies from 898,084 pregnancies among 606,488 mothers. Kidney disorders diagnosed before delivery were identified through hospital diagnostic codes.

Overall, 10,858 babies were born to 7,634 mothers with kidney disorders. Among these births, 3.3% followed assisted reproductive technology, 1.9% followed intrauterine insemination or ovulation induction, and 94.8% were spontaneously conceived. Renal tubulo-interstitial diseases and urolithiasis were the most common kidney disorders.

After adjustment for maternal characteristics, multiple births and selected pre-existing conditions, kidney disorders were associated with higher odds of preterm birth versus no kidney disorder: adjusted OR 2.09 (95% CI 1.62–2.70) after medically assisted reproduction and 1.76 (1.64–1.89) after spontaneous conception. Corresponding odds ratios for low birthweight were 1.69 (1.27–2.27) and 1.54 (1.41–1.67). Caesarean delivery and low Apgar scores were also more likely in both conception groups.

The findings support attention to pregnancy risk among women with kidney disorders regardless of conception method, but do not establish causality. The cohort included only pregnancies resulting in live birth or stillbirth, excluding unsuccessful fertility treatment and miscarriage; medically assisted reproduction success rates therefore could not be assessed.