Abstract
Objective
This study aimed to evaluate the association of increasing birth weight above 4,000
grams and adverse obstetric outcomes and explore the influence of key maternal risk
factors, including prepregnancy body mass index (BMI) and gestational weight gain
(GWG), among births not complicated by diabetes.
Study Design
This was a retrospective cohort study of singleton, non-anomalous, live births between
37 and 42 weeks' gestation in the United States between 2012 and 2021. Births complicated
by diabetes or with birth weights less than 3,000 g were excluded. Births were stratified
into four weight categories: 3,000 to 3,999 g (referent group), 4,000 to 4,499, 4,500
to 4,999, and ≥5,000 g. We performed stratified analyses by prepregnancy BMI and GWG
per the National Academy of Medicine guideline recommendations. Analyses were performed
via chi-square and adjusted incidence risk ratios for statistical comparisons.
Results
There were 23,487,820 births included in this analysis. Higher birth weights were
significantly associated with a higher risk of adverse perinatal outcomes, including
cesarean delivery, blood transfusion, unplanned hysterectomy, maternal ICU admission,
and obstetric anal sphincter injury. Additionally, the adjusted risk of all adverse
neonatal outcomes also increased with increasing birth weight. When stratified by
maternal risk factors, including BMI and GWG groups, we similarly found higher risk
of adverse outcomes among higher birth weight categories, particularly among births
complicated by maternal obesity or GWG above the National Academies of Medicine (NAM)
recommendations.
Conclusion
Among births without diabetes, birth weights above 4,000 g were associated with an
increasingly higher risk of adverse perinatal outcomes, and adverse outcomes remained
higher even after stratification by BMI and GWG.
Key Points
-
Increasing birth weight is associated with higher rates of adverse outcomes.
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Perinatal outcomes by severity of macrosomia have not been thoroughly studied.
-
Obesity and excessive weight gain in pregnancy is associated with adverse neonatal
outcomes.
Keywords
macrosomia - obstetrics - gestational weight gain - body mass index - obesity - cesarean
delivery
