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Am J Perinatol 2024; 41(S 01): e204-e211
DOI: 10.1055/a-1877-8918
Original Article

Association of Maternal Body Mass Index and Maternal Morbidity And Mortality

Mara J. Dinsmoor 
1   Departments of Obstetrics and Gynecology of Northwestern University, Chicago, Illinois
,
Lynda G. Ugwu
2   George Washington University Biostatistics Center, Washington, District of Columbia
,
Jennifer L. Bailit
3   Departments of Obstetrics and Gynecology, MetroHealth Medical Center-Case Western Reserve University, Cleveland, Ohio
,
Uma M. Reddy
4   The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
,
Ronald J. Wapner
5   Departments of Obstetrics and Gynecology, Columbia University, New York, New York
,
Michael W. Varner 
6   Departments of Obstetrics and Gynecology, University of Utah Health Sciences Center, Salt Lake City, Utah
,
John M. Thorp Jr.
7   Departments of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
,
Steve N. Caritis
8   Departments of Obstetrics and Gynecology, University of Pittsburgh, Pittsburgh, Pennsylvania
,
Mona Prasad
9   Departments of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
,
Alan T.N. Tita
10   Departments of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama
,
George R. Saade
11   Departments of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
,
Yoram Sorokin
12   Departments of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan
,
Dwight J. Rouse
13   Departments of Obstetrics and Gynecology, Brown University, Providence, Rhode Island
,
Sean C. Blackwell
14   Departments of Obstetrics and Gynecology, University of Texas Health Science Center at Houston, McGovern Medical School-Children's Memorial Hermann Hospital, Houston, Texas
,
Jorge E. Tolosa
15   Departments of Obstetrics and Gynecology, Oregon Health and Science University, Portland, Oregon
,
for the Eunice Kennedy Shriver National Institute of Child Health Human Development Maternal-Fetal Medicine Units (MFMU) Network* › Author Affiliations
Funding The project described was supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD; grant numbers: HD21410, HD27869, HD27915, HD27917, HD34116, HD34208, U10 HD36801, HD40500, HD40512, HD40544, HD40545, HD40560, HD40485, HD53097, and HD53118) and the National Center for Research Resources (grant numbers: UL1 RR024989 and 5UL1 RR025764). Comments and views of the authors do not necessarily represent views of the National Institutes of Health.
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Abstract

Objective This study aimed to assess the association of maternal body mass index (BMI) with a composite of severe maternal outcomes.

Study Design Secondary analysis of a cohort of deliveries on randomly selected days at 25 hospitals from 2008 to 2011. Data on comorbid conditions, intrapartum events, and postpartum course were collected. The reference group (REF, BMI: 18.5–29.9kg/m2), obese (OB; BMI: 30–39.9kg/m2), morbidly obese (MO; BMI: 40–49.9kg/m2), and super morbidly obese (SMO; BMI ≥ 50kg/m2) women were compared. The composite of severe maternal outcomes was defined as death, intensive care unit (ICU) admission, ventilator use, deep venous thrombosis/pulmonary embolus (DVT/PE), sepsis, hemorrhage, disseminated intravascular coagulation (DIC), unplanned operative procedure, or stroke. Patients in the REF group were matched 1:1 with those in all other obesity groups based on propensity score using the baseline characteristics of age, race/ethnicity, previous cesarean, preexisting diabetes, chronic hypertension, parity, cigarette use, and insurance status. Multivariable Poisson's regression was used to estimate adjusted relative risks (aRRs) and 95% confidence intervals (CIs) for the association between BMI and the composite outcome. Because cesarean delivery may be in the causal pathway between obesity and adverse maternal outcomes, models were then adjusted for mode of delivery to evaluate potential mediation.

Results A total of 52,162 pregnant patients are included in the analysis. Risk of composite maternal outcomes was increased for SMO compared with REF but not for OB and MO [OB: aRR=1.06, 95% CI: 0.99–1.14; MO: aRR=1.10, 95% CI: 0.97–1.25; SMO: aRR=1.32, 95% CI: 1.02–1.70]. However, in the mediation analysis, cesarean appears to mediate 46% (95% CI: 31–50%) of the risk of severe morbidity for SMO compared with REF.

Conclusion Super morbid obesity is significantly associated with increased serious maternal morbidity and mortality; however, cesarean appears to mediate this association. Obesity and morbid obesity are not associated with maternal morbidity and mortality.

Key Points

  • Super morbid obesity is associated with increased morbidity.

  • Cesarean appears to mediate the association between super morbid obesity and morbidity.

  • Obesity and morbid maternal obesity are not associated with morbidity.

Keywords

obesity - maternal morbidity - cesarean delivery - propensity score analysis

Note

Presented in part at the 38th annual meeting of the Society for Maternal-Fetal Medicine, January 29–February 3, 2018, Dallas, TX.


Supplementary Material



Publication History

Received: 12 July 2021

Accepted: 02 June 2022

Accepted Manuscript online:
16 June 2022

Article published online:
02 September 2022

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