A large population-based study published in JAMA Network Open reports that newborns born to mothers with multiple chronic conditions face a higher risk of severe neonatal morbidity or mortality, with risk increasing as the number, complexity, and severity of maternal conditions rise.
The study analyzed data from 1,018,968 singleton live births in Ontario, Canada, between 2012 and 2021. Using linked administrative health records, researchers identified maternal chronic conditions documented in the two years before conception and examined their association with severe neonatal morbidity or mortality (SNM-M), a validated composite outcome that includes serious neonatal diagnoses, critical procedures, and death within 28 days of birth.
Maternal chronic conditions were defined using diagnostic codes for 22 physical and mental health conditions, including diabetes, chronic hypertension, cardiac disease, obesity, inflammatory bowel disease, mood and anxiety disorders, and autoimmune conditions. Mothers were categorized as having zero, one, two, or three or more chronic conditions.
The analysis showed a clear dose-response relationship. Compared with newborns of mothers without chronic conditions, the adjusted relative risk of SNM-M increased to 1.26 for one maternal condition, 1.58 for two conditions, and 2.01 for three or more conditions. Similar trends were observed for preterm birth and major congenital anomalies.
Risk varied by condition profile. Newborns of mothers with complex multiple chronic conditions – defined as three or more conditions affecting at least three body systems – had nearly double the risk of SNM-M. Cardiometabolic conditions, including diabetes, hypertension, obesity, and cardiovascular disease, were associated with particularly elevated risk. The highest risk was seen when maternal chronic conditions were severe enough to require hospitalization during pregnancy, with more than a threefold increase in SNM-M risk.
The study highlights the importance of structured maternal health data in neonatal risk stratification. SNM-M was measured using the Neonatal Adverse Outcomes Indicator, which captures diagnoses such as seizures and respiratory failure as well as procedures including newborn resuscitation – events commonly documented in neonatal intensive care and pathology workflows.
The authors note that chronic disease burden may influence neonatal outcomes through mechanisms such as placental dysfunction, impaired fetal growth, medication interactions, and clinician-initiated preterm delivery. Because maternal conditions were identified before pregnancy, the findings support a role for preexisting maternal health in shaping neonatal risk.
Although limited by reliance on administrative diagnostic codes and the absence of laboratory severity markers, the study used validated algorithms and showed consistent results across sensitivity analyses. The findings underscore the value of integrating maternal chronic disease history into prenatal assessment and postnatal diagnostic interpretation.
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