Different maternal age patterns of preterm birth: Interplay of race/ethnicity, chronic stress, and marital status

The aim of this study was to examine whether the preterm birth (PTB) risks according to maternal age is altered by a woman's marital status and chronic stress among non-Hispanic (N-H) White, N-H Black, Hispanic, and Asian women. This researcher analyzed the Pregnancy Risk Assessment Monitoring System data for New York City and Washington State linked with the birth certificates for 2004-2007. The sample included 6344 singleton live births without birth defects to women aged 18 years or older identified as N-H White, N-H Black, Hispanic, or Asian. The outcome was PTB. Maternal age-specific PTB rates were calculated according to race/ethnicity, marital status, and chronic stress. Linear trends of PTB rates with maternal age were evaluated by the Mantel-Haenszel χ² test. Marriage had a protective effect against PTB at advancing maternal age across racial/ethnic groups. The health benefit of marriage was strong, particularly among the married N-H Black and Asian women, manifested as a maternal age-related decrease in the PTB rate (reverse-weathering). In contrast, women not married showed a maternal age-related increase in the PTB rate (weathering) across the racial/ethnic groups. Under higher chronic stress, married women generally experienced less weathering about PTB. These patterns were observed with noticeable racial/ethnic variations. Acknowledging the different dynamics among maternal age, marital status, and chronic stress by race/ethnicity could help shed light on the psychosocial mechanisms underlying the racial/ethnic inequalities in PTB in the United States. To that end, future studies should use more nuanced measurements of paternal support and chronic stress.