Weight in early pregnancy and outcomes in early infancy

Overweight and obesity are increasing among women of childbearing age worldwide.1 Consequently, a sizable group of women begin pregnancy as overweight or obese, increasing the risk of complications in both mother and infant.2

In the linked cohort study based on national registers, Johansson and colleagues (doi:10.1136/bmj.g6572) assessed the association of maternal body mass index (BMI, weight (kg)/(height (m)²)) in early pregnancy with infant mortality risk in more than 1.8 million singleton live births in Sweden.3 Causes of infant death were also reported. Maternal BMI was calculated from measured body weight and self reported height at the first antenatal visit, and categorized as underweight (BMI ≤18.4), normal weight (18.5-24.9), overweight (25.0-29.9), obese grade 1 (30.0-34.9), obese grade 2 (35.0-39.9), and obese grade 3 (≥40.0).

Infants born to overweight or mildly obese women had an increased mortality relative to infants born to normal weight mothers. The increase was modest but statistically significant. Consistent with previous studies,4 5 the greatest risk of infant mortality …