Original ResearchSevere maternal morbidity and mortality during delivery hospitalization of class I, II, III, and super obese women
Introduction
More than one-third (35% or 78.6 million) of adults in the United States have obesity.1 Obesity is defined as a body mass index (BMI) of 30 kg/m2 or higher.1 Obesity leads to multiple preventable conditions, including hypertension, diabetes, cardiovascular disease, and stroke. Women who are overweight (BMI, 25–29.9 kg/m2) or obese are more likely to suffer from complications in pregnancy. A 2015 study in California showed that women with obesity had a significantly higher risk for pregnancy-related mortality owing to cardiovascular disease and venous thromboembolism.2 In this population, women with morbid obesity (BMI >40) were at highest risk of pregnancy-related mortality.2 A review by Campbell et al3 of maternal mortality during delivery hospitalization in New York City from 1995 to 2003 showed that women with obesity were 190% more likely to die during delivery hospitalization than women without obesity.
For every maternal death, there are many more severe complications that are associated with pregnancy, labor, and delivery that do not result in death. These events are identified as severe maternal morbidity (SMM).4
A preliminary analysis from Michigan found that pregnancy-related deaths were 3.7 times more common in the obese vs nonobese population.5 The rates of women with a BMI of >40 and >50 has increased by over 70% in the last 20 years in the United States population.6 The surgical literature has included the class of super obesity, defined as BMI >50 kg/m2 or 225% of ideal body weight.7 Rates of super obesity have rapidly increased over time.8 Studies on the super obese population in obstetrics demonstrate a 5-fold increased risk of maternal intensive care unit admission;9 5-fold increased risk of neonatal morbidity; and increased risks of wound complications, postpartum hemorrhage, prolonged hospital stay, preeclampsia, cesarean delivery, and macrosomia.10, 11, 12, 13 In addition, there is a dose-response relationship in the relationship between BMI and adverse perinatal outcomes for both the neonate and the mother.9,10 Lisonkova et al14 examined the association between increasing BMI categories and SMM events and found that women with higher BMI were at increased risk of SMM events.
However, data are limited regarding the impact of super obesity on the overall risk of SMM and on the individual Centers for Disease Control and Prevention (CDC) SMM indicators.
In our study, we sought to examine the effects of increasing classes of obesity and super obesity on SMM and mortality at the time of delivery hospitalization in a racially and ethnically diverse population.
Section snippets
Materials and Methods
We conducted a retrospective cohort study on all singleton births from 20 to 45 weeks of gestation in New York City from 2008 to 2012, using birth certificate records linked to hospital discharge data from the Statewide Planning and Resource Cooperative System. Information regarding mother's age, race, and pregnancy information were derived from the birth certificate, and information regarding length of stay, diagnoses, and procedure codes were obtained from the hospital discharge data. A more
Results
There were 588,232 live singleton births in New York City from 2008 to 2012. After excluding women without available information on prepregnancy BMI (n=7316), multiple gestations (n=9309), implausible gestational age (n=125), or maternal age (n=384), our final analytical sample included a total of 570,997 women (Figure). Approximately 1.2% of deliveries were excluded because of missing information regarding prepregnancy BMI.
The overall rate of SMM in our sample was 20.3 per 1000 deliveries. In
Principal findings
This large population-based study of singleton births in New York City from 2008 to 2012 found that women with class II, class III, and super obesity were all at significantly increased risk of SMM during delivery hospitalization. Increasing classes of obesity were also significantly associated with individual SMM events defined using the CDC indicators.
Results
Based on our findings, there is a significant dose-response relationship between increasing obesity class and risk of SMM at the time of delivery hospitalization. These risks seem to be highest in women with BMI >40, specifically those women with class III and super obesity. The odds of increased SMM remained significant even when transfusions were excluded. These findings are consistent with previous studies regarding the increased risks of adverse maternal outcomes in obese women.2,3,9,14
Conclusions
Maternal morbidity and mortality continue to rise in the United States and are often preventable.2 Identification of potentially modifiable risk factors, prevention of the development of obesity, and early screening for underlying comorbidities in a high risk population are crucial steps in preventing maternal deaths and improving maternal healthcare in the United States.
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2023, American Journal of Perinatology
The authors report no conflict of interest.
The findings of the article were presented at the 40th annual meeting of the Society for Maternal-Fetal Medicine, Grapevine, TX, February 7, 2020.
Cite this article as: Platner MH, Ackerman CM, Howland RE, et al. Severe maternal morbidity and mortality during delivery hospitalization of class I, II, III, and super obese women. Am J Obstet Gynecol MFM 2021;XX:x.ex–x.ex.