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Higher BMI before, during pregnancy increased risk for fetal, infant death
Higher maternal BMI before or during early pregnancy increases the risks for fetal death and stillbirth, as well as neonatal, perinatal and infant death, according to a review published in JAMA.
The meta-analysis by Dagfinn Aune, MS, of the Imperial College London, and colleagues examined 38 cohort studies published on PubMed and Embase databases that reported adjusted RRs for fetal death, stillbirth or infant death by at least three categories of maternal BMI. The combined studies included 10,147 fetal deaths, more than 16,274 stillbirths, more than 4,311 perinatal deaths, 11,294 neonatal deaths and 4,983 infant deaths.
From each study, researchers extracted the number of participants or pregnancies, number of deaths, BMI by subgroup, cutoff values for BMI categories, RR (95% CIs) and adjustment for co-founding factors. Summary RRs were calculated using a random-effects model.
The summary RR per 5-unit increase in maternal BMI for fetal death was 1.21 (95% CI, 1.09-1.35); for stillbirth, 1.24 (95% CI, 1.18-1.3); for perinatal death, 1.16 (95% CI, 1-1.35); for neonatal death, 1.15 (95% CI, 1.07-1.23); and for infant death, 1.18 (95% CI, 1.09-1.28). The researchers found a significant nonlinear association in all analyses, with fetal the most pronounced.
Even modest increases in maternal BMI were associated with higher risks for fetal death, stillbirth, neonatal death, perinatal death and infant death, according to the findings. Severely obese women had the greatest risk; women with a BMI of 40 had were approximately two to three times more likely to experience these outcomes vs. women with a BMI of 20.
“Weight management guidelines for women who plan pregnancies should take these findings into consideration to reduce the burden of fetal deaths, stillbirths, and infant deaths,” the researchers wrote. Still, the optimal BMI for prevention is not yet known, according to the study.
Disclosure: This project was supported by a grant from the Norwegian SIDS and Stillbirth Society, Oslo, Norway.