Maternal obesity is associated with congenital anomalies of the kidney and urinary tract in offspring.

BACKGROUND: Congenital abnormalities of the kidney and urinary tract (CAKUT) are diagnosed in up to 1 % of pregnancies and account for 20-30 % of the abnormalities identified in the prenatal period. In previous studies, maternal obesity has been associated with congenital malformations in offspring. Our aim was to evaluate the association between maternal obesity [body mass index (BMI) ≥ 30 kg/m2] and CAKUT in offspring. METHODS: We conducted a population-based, case-control study using linked birth-hospital discharge records from Washington State, 2003-2012. We identified 3093 CAKUT cases using International Classification of Diseases, Ninth Revision (ICD-9) codes. Controls were defined as births without any ICD-9 codes denoting congenital malformations, matched to cases by year of birth in an approximate 4:1 ratio. RESULTS: Compared to controls, mothers giving birth to infants with CAKUT were more likely to be obese [odds ratio (OR) 1.24, 95 % confidence interval (CI) 1.11-1.38]. We found a significant positive trend between odds of CAKUT in offspring and increasing severity of obesity (score test for trend of odds p < 0.001). This association remained significant in offspring with isolated CAKUT (OR 1.19, 95 % CI 1.06-1.35) and upper urinary tract anomalies (OR 1.26, 95 % CI 1.13-1.41). Maternal overweight (BMI 25-29.9 kg/m2) was not associated with CAKUT in offspring. CONCLUSIONS: Our results demonstrate a positive association between maternal obesity and CAKUT in offspring, as well as between obesity severity and the odds of CAKUT in offspring. These findings provide additional evidence for the public health importance of obesity, particularly as a potentially modifiable risk factor.