Multiple Maternal Chronic Conditions Increase Risk of Severe Neonatal Outcomes: Study

A new study published in the Journal of the American Medical Association showed that there was a dose-response relationship between the number of pre-existing maternal chronic illnesses and the likelihood of severe newborn morbidity or fatality.

Multiple chronic diseases (MCC) affect around 16% of pregnant women, and the number of prior conditions raises the risk of severe maternal morbidity and mortality in a dose-response fashion. Newborn outcomes in this cohort, however, are little understood. Thus, the purpose of this study was to investigate the relationship between the risk of severe neonatal morbidity or mortality (SNM-M) and the number of previous maternal chronic illnesses, as well as the presence of MCC complexity, cardiometabolic MCC, and MCC severity.

From 2012 to 2021, all live births in Ontario, Canada, were included in this population-based cohort study. From September 2024 until November 2025, data were examined. In the two years before to conception, maternal MCC was measured. The number of chronic conditions, MCC complexity (≥3 chronic conditions in ≥3 body systems), co-occurring cardiometabolic conditions, and MCC severity indicated by a prenatal hospitalization for a chronic illness were used to generate adjusted relative risks (aRRs) for SNM-M using modified Poisson regression. Age, parity, immigrant status, income quintile, and rurality were all taken into account while adjusting multivariable models.

The cohort consisted of 1,018,968 newborns, of which 20,934 were born to mothers with three or more chronic conditions, 73,768 to mothers with two chronic conditions, 276,765 to mothers with one chronic condition (mean [SD] maternal age, 30.7 [5.4] years), and 647,501 to mothers with none (mean [SD] maternal age, 31.0 [5.1] years).

Newborns of mothers with one (1.26; 95% CI, 1.24-1.28), two (1.58; 95% CI, 1.54-1.62), and three or more (2.01; 95% CI, 1.94-2.09) chronic illnesses showed a dose-response increase in the aRR for SNM-M. Additionally, complicated severe MCC (3.11; 95% CI, 2.55-3.79), MCC (1.97; 95% CI, 1.88-2.06) and cardiometabolic MCC (2.67; 95% CI, 2.24-3.19) all had higher aRRs.

Overall, for family doctors, pediatrics, and pregnancy care clinicians, this cohort study offers clinically significant findings. Maternal multiple chronic diseases and newborn problems are linked, which emphasizes the need to optimize chronic disease care prior to conception and eliminate modifiable risk factors such poverty, physical inactivity, and poor nutrition. 

Source:

Brown, H. K., Fung, K., Cohen, E., Dennis, C.-L., Grandi, S. M., Rosella, L. C., Varner, C., Vigod, S. N., Wigle, J., Wodchis, W. P., & Ray, J. G. (2026). Multiple maternal chronic conditions and risk of severe neonatal morbidity and mortality. JAMA Network Open, 9(1), e2555558. https://doi.org/10.1001/jamanetworkopen.2025.55558