Impact of Maternal BMI on Urinary Pathology Severity in Pregnancy

The objective of this study is to compare the severity of urinary pathology among women of normal weight, class 1,2 and class 3 obesity. We conducted a retrospective cohort study of women with UTI (acute cystitis or asymptomatic bacteriuria) at a single healthcare system from 7/2013-5/2019. Demographic, infectious, antepartum, and intrapartum data were abstracted. Women with missing BMI or infection data were excluded. Subjects were categorized into < 25 BMI, 30-40 and > 40 based on BMI at their new prenatal visit. The primary outcome was progression to pyelonephritis, and secondary outcomes were recurrent UTI and pyelonephritis-related morbidities. Simple statistics were used to analyze the data and regression analyses were performed to control for confounders. Of 419 patients who met inclusion criteria, 171 had normal weight, 184 had BMI 30-40, and 64 had BMI > 40. As BMI increased, subjects were more likely to be Black, multiparous, and have chronic hypertension and diabetes mellitus type II (p < 0.001). Progression to pyelonephritis did not differ as BMI increased, nor did pyelonephritis-related morbidity, though these were rare (Table). Mothers with BMI 30-40 and > 40 had a slightly increased risk of recurrent UTIs compared to normal weight women (Table). When controlling for confounders, no increase in relative risk of developing pyelonephritis was seen (BMI 30-40:RR=1.06,95%CI 0.58-1.93; BMI > 40:RR=0.59,95%CI:0.24-1.41). Though women with BMI 30-40 did have increased risk of developing recurrent infection (RR=1.68,95%CI:1.10-2.59), this did not extend to women with BMI > 40 (RR=1.04,95%CI:0.62-2.07). Women with recurrent infection were not more likely to develop pyelonephritis or pyelonephritis-related morbidity (data not shown). In this cohort, BMI did not impact risk of developing pyelonephritis. Even among patients with recurrent UTI, BMI did not impact the risk of progressing to pyelonephritis. Larger studies are needed to further investigate these findings to better understand the relationship between increasing BMI and severity of urinary pathology.