Maternal Migration Background and Mortality Among Infants Born Extremely Preterm.

Importance: Extremely preterm infants require care provided in neonatal intensive care units (NICUs) to survive. In the Netherlands, a decision is made regarding active treatment between 24 weeks 0 days and 25 weeks 6 days after consultation with the parents.

Objective: To investigate the association between maternal migration background and admissions to NICUs and mortality within the first year among extremely preterm infants.

Design, Setting, And Participants: This cross-sectional study linked data of registered births in the Netherlands with household-level income tax records and municipality and mortality registers. Eligible participants were households with live births at 24 weeks 0 days to 25 weeks 6 days gestation between January 1, 2010, and December 31, 2017. Data linkage and analysis was performed from March 1, 2020, to June 30, 2023.

Exposure: Maternal migration background, defined as no migration background vs first- or second-generation migrant mother.

Main Outcomes And Measures: Admissions to NICUs and mortality within the first week, month, and year of life. Logistic regressions were estimated adjusted for year of birth, maternal age, parity, household income, sex, gestational age, multiple births, and small for gestational age. NICU-specific fixed effects were also included.

Results: Among 1405 live births (768 male [54.7%], 546 [38.9%] with maternal migration background), 1243 (88.5%) were admitted to the NICU; 490 of 546 infants (89.7%) born to mothers with a migration background vs 753 of 859 infants (87.7%) born to mothers with no migration background were admitted to NICU (fully adjusted RR, 1.03; 95% CI, 0.99-1.08). A total of 652 live-born infants (46.4%) died within the first year of life. In the fully adjusted model, infants born to mothers with a migration background had lower risk of mortality within the first week (RR, 0.81; 95% CI, 0.66-0.99), month (RR, 0.84; 95% CI, 0.72-0.97), and year of life (RR, 0.85; 95% CI, 0.75-0.96) compared with infants born to mothers with no migration background.

Conclusions: In this nationally representative cross-sectional study, infants born to mothers with a migration background at 24 weeks 0 days to 25 weeks 6 days of gestation in the Netherlands had lower risk of mortality within the first year of life than those born to mothers with no migration background, a result that was unlikely to be explained by mothers from different migration backgrounds attending different NICUs or differential preferences for active obstetric management across migration backgrounds. Further research is needed to understand the underlying mechanisms driving these disparities, including parental preferences for active care of extremely preterm infants.