Pre-pregnancy maternal obesity linked to severe morbidity and mortality: JAMA Study

Columbus: A new study in JAMA Network Open found that maternal pre-pregnancy obesity was related to an increased risk of severe maternal morbidity (SMM) and/or death. This association may be mediated by hypertensive disorders, suggesting that improved prevention and management of hypertensive disorders in pregnancy may reduce morbidity and mortality in obese people. 

According to the available research, the relationship between body mass index (BMI, which is computed as weight in kilograms divided by height in meters squared) and severe maternal morbidity and/or death is questionable. As a result, Heather A. Frey and colleagues conducted the study to investigate the relationship between pre-pregnancy BMI and SMM and/or mortality through 1 year postpartum, as well as to identify both the direct and indirect implications of maternal obesity for SMM and/or mortality by investigating hypertensive disorders and pre-gestational diabetes as potential mediators.

This population-based cohort research was carried out from March to October 2021, utilizing vital records and associated Medicaid claims data from January 1, 2012, to December 31, 2017. The group included pregnant Medicaid users who delivered at 20 weeks or later and had pre-pregnancy BMI data. The key risk factor was maternal BMI before pregnancy, which was classified,

1. underweight (18.5), 2. healthy weight (<18.5-24.9), 3. overweight (25.0-29.9), 4. class 1 obesity (30.0-34.9), 5. class 2 obesity (35.0-39.9), and 6. class 3 obesity (≥40.0).

The main result was a composite of SMM and/or maternal mortality during 20 weeks' gestation and 1 year postpartum (as defined by the Centers for Disease Control and Prevention). Additional time periods were studied, including 20 weeks' gestation to delivery hospitalization and 20 weeks' gestation to 42 days postpartum. The adjusted relative risks for the primary outcome based on BMI category were estimated using generalized estimating equation models. Maternal hypertension and pre-gestational diabetes were identified as possible mediators.

The key findings of this study were as follow:

1. The incidence of maternal obesity was 30.5% (n = 106 031) in a cohort of 347 497 pregnancies among 276 691 Medicaid participants.

2. In 5.3% of pregnancies (n = 18 398), the composite SMM and/or mortality result occurred.

3. Overweight and obesity were linked to an increased risk of SMM and/or death from pregnancy to one year postpartum as compared to healthy BMI.

4. Similar results were obtained when the follow-up period was reduced to 42 days postpartum or when the baby was hospitalized.

5. 65.1% of the link between obesity and the main outcome was mediated by hypertension.

In conclusion, hypertensive disorders were found to modulate this relationship, implying that better prevention and treatment of hypertensive disorders during pregnancy may lower morbidity and death in obese patients.

Reference:

Frey, H. A., Ashmead, R., Farmer, A., Kim, Y. H., Shellhaas, C., Oza-Frank, R., Jackson, R. D., Costantine, M. M., & Lynch, C. D. (2022). Association of Prepregnancy Body Mass Index With Risk of Severe Maternal Morbidity and Mortality Among Medicaid Beneficiaries. In JAMA Network Open (Vol. 5, Issue 6, p. e2218986). American Medical Association (AMA). https://doi.org/10.1001/jamanetworkopen.2022.18986