Severity of excessive gestational weight gain and risk of severe maternal morbidity

Both obesity and excessive gestational weight gain are associated with severe maternal morbidity, but there is limited literature evaluating whether the risk of severe maternal morbidity is further increased by the degree or severity of excessive gestational weight gain.

This study aimed to determine whether pregnant patients with excessive gestational weight gain who gained more than 50 lb were at increased risk of severe maternal morbidity compared with those who only moderately exceeded recommended gestational weight gain guidelines. A secondary objective was to determine whether patients who gained 10 lb more than the recommended upper limit of total weight gain for a given prepregnancy body mass index group were at increased risk of severe maternal morbidity compared with those who exceeded that upper limit by a lesser amount.

This was a retrospective cohort study of all patients with live, term, singleton deliveries with excessive gestational weight gain from 7 hospitals within a large health system in New York between January 2019 and February 2020. Excessive gestational weight gain was defined as exceeding the recommended upper limit of total weight gain for a given prepregnancy body mass index category using the National Academy of Medicine gestational weight gain guidelines: >40 lb for a body mass index of <18.5 kg/m², >35 lb for a body mass index of 18.5 to 24.9 kg/m², >25 lb for a body mass index of 25.0 to 29.9 kg/m², and >20 lb for a body mass index of ³30.0 kg/m². Patient height and weight data were self-reported at the time of delivery hospitalization and retrieved from the electronic medical record system. Patients were classified into 2 excessive gestational weight gain groups: moderate (≤50 lb) or severe (>50 lb). Patients with missing body mass index or gestational weight gain were excluded. The primary exposure was severe excessive gestational weight gain. The primary outcome was severe maternal morbidity, defined using the Centers for Disease Control and Prevention criteria. Logistic regression was used to model the likelihood of severe maternal morbidity, adjusting for race and ethnicity, nulliparity, advanced maternal age, gestational diabetes mellitus, and maternal mood disorder. For the secondary analysis, severe maternal morbidity rates were compared between patients who exceeded their body mass index-specific upper limit of total weight gain by ≥10 lb and those who exceeded it by <10 lb.

A total of 11,506 patients were included for analysis, and 1965 patients (17.1%) had severe excessive gestational weight gain. The overall rate of severe maternal morbidity was 3.3%. Severe maternal morbidity occurred in 85 of 1965 patients (4.3%) with severe excessive gestational weight gain and 292 of 9541 patients (3.1%) with moderate excessive gestational weight gain. On regression analysis, after adjustment for covariate factors, patients with a severe excessive gestational weight gain were 39% more likely to experience severe maternal morbidity than those with moderate excessive gestational weight gain (adjusted odds ratio, 1.39; 95% confidence interval, 1.08-1.79). Patients with excessive gestational weight gain of ≥10 lb above the recommended body mass index-specific upper limit for gestational weight gain were 32% more likely (adjusted odds ratio, 1.32; 95% confidence interval, 1.07-1.62) to experience severe maternal morbidity than patients who exceeded that upper limit by <10 lb.

Patients with live, term, singleton pregnancies who gain more than 50 lb are at increased risk of severe maternal morbidity compared with those who only moderately exceed gestational weight gain guidelines. Similarly, patients who gain ≥10 lb above the recommended body mass index-specific upper limit for gestational weight gain are at increased risk. Further study is warranted to determine the most effective interventions to manage gestational weight gain and mitigate maternal risk.