Exploring Weathering: the Relation of Age to Low Birth Weight Among First Generation and Established United States-Born Mexican–American Women

To determine the age-related patterns of low birth weight, preterm birth, and intrauterine growth retardation among first
generation and established US-born Mexican–American mothers. We performed stratified analyses on an Illinois transgenerational
dataset of Mexican–American infants (1989–1991) and their mothers (1956–1976) with appended U.S. census income information.
In Cook County, Illinois established (second or higher generation) US-born Mexican–American women (N = 2,006) had a low birth
weight (<2,500 g) rate of 6.2% compared to 4.8% for first generation US-born Mexican–American women (N = 1,450), RR = 1.3
(1.0–1.6). In both subgroups, low birth weight, preterm, and intrauterine growth retarded components rates did not increase
with advancing maternal age. First generation 30–35 year old US-born Mexican–American women (N = 159) had a low birth weight
rate of 3.1% compared to 4.2% for their teen counterparts (N = 386), RR = 0.8 (0.3–2.0). Established 30–35 year old US-born
Mexican–American women (N = 330) had a low birth weight rate of 4.9% compared to 7.4% for their teen counterparts (N = 459),
RR = 0.7 (0.4–1.2). There was no evidence of weathering among US-born Mexican–American mothers with a lifelong residence in
lower income neighborhoods, with a general downward trend in low birth weight rates with increasing age until age 30–35. Rates
of low birth weight, preterm birth, and intrauterine growth retardation do not increase with advancing age among first generation
and established US-born 15–35 year old Mexican–American women. This trend persists among both generations of women with a
lifelong residence in lower income neighborhoods.