Weighing the risk for severe maternal morbidity

PHOTO: TAREQ SALAHUDDIN

The U.S. obesity epidemic markedly affects pregnant women, but its consequences have not been well quantified. To explore the relation between pre-pregnancy body mass index (BMI) and severe maternal morbidity (stroke, renal failure, sepsis, shock, uterine rupture, intensive care unit admission, and maternal death), investigators analysed the outcomes of 743,630 singleton births in Washington state from 2004 to 2013. BMI distributions were 3% low (<18.5 kg/m2), 48% normal (18.5–24.9), 26% overweight (25.0–29.9), 13% obesity class 1 (30–34.9), 6% obesity class 2 (35–39.9) and 4% obesity class 3 (≥40).

Rates of severe maternal morbidity per 10,000 women were 172 (low BMI), 143 (normal BMI), 160 (overweight), 168 (class 1 obesity), 178 (class 2 obesity) and 203 (class 3 obesity). Adjusted odds ratios relative to normal BMI were 1.1 (low BMI), 1.1 (overweight), 1.1 (class 1 obesity), 1.2 (class 2 obesity) and 1.4 (class 3 obesity), all significantly different. These odds ratios were not adjusted for cesarean delivery rates, which ranged from 19% (low BMI) to 49% (class 3 obesity).