The relation of age to low birth weight rates among foreign-born black mothers: a population-based exploratory study.

BACKGROUND

In stark contrast to the J or U- shaped relationship between age and low birth weight rates (< 2500g) seen among non-Latino White and Mexican American mothers, low birth weight rates among US-born Blacks are lowest in their teens and rise with increasing age (ie, weathering). The age-related pattern of low birth weight rates among foreign-born Black mothers is unknown.

OBJECTIVE

To determine the relationship between age and low birth weight rates among foreign-born Black mothers.

DESIGN

Stratified analyses were performed on the 2003-2004 National Center for Health Statistics vital record datasets of foreign-born Black mothers. Maternal age was categorized into six subgroups. Potential confounding variables examined included marital status, parity, and prenatal care usage.

RESULTS

Foreign-born Black mothers (N = 143,235) demonstrated a J/U-shaped age-related pattern of low birth weight rates with the lowest rates observed among those in their twenties and early thirties. The subgroups of 15-19 and 35-39 year old mothers had low birth weight rates of 12.0% and 11.4% compared to 9.1% for 25-29 year old mothers; RR = 1.31 (1.22-1.42) and 1.25 (1.20-1.31), respectively. The J/U-shaped age-related pattern persisted independent of marital status, parity and prenatal care usage.

CONCLUSIONS

Foreign-born black mothers do not exhibit a weathering pattern of rising low birth weight rates with advancing age regardless of traditional individual-level risk factors. Further research into the age-related pattern of birth outcome among impoverished foreign-born Black mothers is warranted.