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 Ushaped 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 agerelated 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 agerelated 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 oldmothers; RR=1.31 (1.22-1.42) and 1.25 (1.20-1.31), respectively. The J/Ushaped 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 foreignborn Black mothers is warranted.