Spatiotemporal patterns and surveillance artifacts in maternal mortality in the United States: a population-based study

K S Joseph; Sarka Lisonkova; Amélie Boutin; Giulia M Muraca; Neda Razaz; Sid John; Yasser Sabr; Sophie Simon; Johanna Kögl; Elizabeth A Suarez; Wee-Shian Chan; Azar Mehrabadi; Justin S Brandt; Enrique F Schisterman; Cande V Ananth

doi:10.1016/j.lana.2024.100902

Spatiotemporal patterns and surveillance artifacts in maternal mortality in the United States: a population-based study

Lancet Reg Health Am. 2024 Oct 4:39:100902. doi: 10.1016/j.lana.2024.100902. eCollection 2024 Nov.

Authors

K S Joseph^{1

2}, Sarka Lisonkova^{1

2}, Amélie Boutin³, Giulia M Muraca⁴, Neda Razaz⁵, Sid John¹, Yasser Sabr¹, Sophie Simon¹, Johanna Kögl^{1

6}, Elizabeth A Suarez^{7

8}, Wee-Shian Chan⁹, Azar Mehrabadi¹⁰, Justin S Brandt¹¹, Enrique F Schisterman¹², Cande V Ananth^{8

13

14

15}

Affiliations

¹ Department of Obstetrics and Gynaecology, University of British Columbia and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver, Canada.
² School of Population and Public Health, University of British Columbia, Vancouver, Canada.
³ Department of Pediatrics, Faculty of Medicine, Université Laval and CHU de Québec-Université Laval Research Center, Québec City, Canada.
⁴ Departments of Obstetrics and Gynecology, and Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Canada.
⁵ Clinical Epidemiology Division, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
⁶ Department of Obstetrics and Gynecology, Medical University Innsbruck, Innsbruck, Austria.
⁷ Center for Pharmacoepidemiology and Treatment Science, Rutgers Institute for Health, Health Care Policy and Aging Research, New Brunswick, NJ, USA.
⁸ Division of Epidemiology and Biostatistics, Department of Obstetrics, Gynecology, and Reproductive Sciences, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA.
⁹ Department of Medicine, University of British Columbia and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver, Canada.
¹⁰ Perinatal Epidemiology Research Unit, Departments of Obstetrics & Gynaecology and Pediatrics, Dalhousie University, Halifax, Canada.
¹¹ Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, NYU Grossman School of Medicine, New York, USA.
¹² Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
¹³ Department of Biostatistics and Epidemiology, Rutgers School of Public Health, Piscataway, NJ, USA.
¹⁴ Cardiovascular Institute of New Jersey and Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA.
¹⁵ Environmental and Occupational Health Sciences Institute, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA.

Abstract

Background: Reports of high and rising maternal mortality ratios (MMR) in the United States have caused serious concern. We examined spatiotemporal patterns in cause-specific MMRs, in order to obtain insights into the cause for the increase.

Methods: The study included all maternal deaths recorded by the Centers for Disease Control and Prevention from 1999 to 2021. Changes in overall and cause-specific MMRs were quantified nationally; in low-vs high-MMR states (i.e., MMRs <20 vs ≥26 per 100,000 live births in 2018-2021); and in California vs Texas (populous states with low vs high MMRs). Cause-specific MMRs included those due to unambiguous causes (e.g., selected obstetric causes such as pre-eclampsia/eclampsia) and less-specific/potentially incidental causes (e.g., "other specified pregnancy-related conditions", chronic hypertension, and malignant neoplasms).

Findings: MMRs increased from 9.60 (n = 1543) in 1999-2002 to 23.5 (n = 3478) per 100,000 live births in 2018-2021. The temporal increase in MMRs was smaller in low-MMR states (from 7.82 to 14.1 per 100,000 live births) compared with high-MMR states (from 11.1 to 31.4 per 100,000 live births). MMRs due to selected obstetric causes decreased to a similar extent in low-vs high-MMR states, whereas the increase in MMRs from less-specific/potentially incidental causes was smaller in low- vs high-MMR states (MMR ratio (RR) 5.57, 95% CI 4.28, 7.25 vs 7.07, 95% CI 5.91, 8.46), and in California vs Texas (RR 1.67, 95% CI 1.03, 2.69 vs 10.8, 95% CI 6.55, 17.7). The change in malignant neoplasm-associated MMRs was smaller in California vs Texas (RR 1.21, 95% CI 0.08, 19.3 vs 91.2, 95% CI 89.2, 94.8). MMRs from less-specific/potentially incidental causes increased in all race/ethnicity groups.

Interpretation: Spatiotemporal patterns of cause-specific MMRs, including similar reductions in unambiguous obstetric causes of death and variable increases in less-specific/potentially incidental causes, suggest misclassified maternal deaths and overestimated maternal mortality in some US states.

Funding: This work received no funding.

Keywords: Cause of death; Epidemiology; Maternal mortality; Pregnancy complications; Surveillance; United States.