Maternal History of Maltreatment and Infant Birth Weight
Pregnancy during adolescence is associated with later adversities for both mother and child, including low birth weight. Although the mechanisms remain unclear, low birth weight among infants born to teenage mothers may be attributable to health behaviors, access to reproductive health services, or unmeasured maternal selection effects. Pregnant teens with a history of maltreatment may have an acute vulnerability to poor birth outcomes. This presentation explores maternal maltreatment history as an independent predictor of low birth weight among infants born to teenage mothers.
METHODS:
This study uses vital birth records probabilistically matched to administrative child protective service (CPS) records for the state of California. The records of all singleton infants born between 2007 and 2009 to mothers aged 12–19 years were extracted from vital birth files. These records were linked to CPS data to identify teenage mothers for whom an allegation of maltreatment victimization had been substantiated after age 10 and before birth. Low birth weight was based on a gestational weight threshold of 2,500 grams. To isolate the potential effect of maternal maltreatment, a number of potential confounders were included: maternal age; birth order; maternal race/ethnicity; cigarette smoking during pregnancy; birth payment method; prenatal care initiation; Women, Infant, Children (WIC) utilization; and infant gender. Descriptive statistics were computed and χ2 tests used to compare the distribution of maternal maltreatment and other sociodemographic characteristics stratified by infant birth weight. To examine the effect of maternal maltreatment, a log Poisson regression model with a robust variance estimation was specified.
RESULTS:
Of the 153,762 singleton births to teenage mothers in California between January 1, 2007 and December 31, 2009, 7.1% (n = 10,886) were low birth weight. Among teenage mothers, 13.6% had been substantiated as a victim of maltreatment after age 10 and before giving birth. Maternal maltreatment history was associated with a 10% increased risk of low birth weight (RR: 1.10; 95% CI: 1.04-1.16). Maternal smoking, prenatal care, and other confounders modestly attenuated the association between maternal victimization and infant birth weight, yet after adjusting for these other factors, the risk of low birth weight was still 6% greater among infants born to adolescent mothers with a maltreatment history (RR: 1.06; 95% CI: 1.01-1.12). Bivariate associations observed for covariates continued to emerge in the multivariable model, with the largest relative differences in birth weight associated with race/ethnicity, smoking, and WIC utilization.
CONCLUSIONS AND IMPLICATIONS:
This study identified the maltreatment history of adolescent mothers as a significant and independent hazard associated with low birth weight. This finding aligns with research which suggests that maltreatment and other adversities negatively affect health and well-being throughout the life course. The association between a history of maltreatment victimization and infant birth weight may reflect physiological changes or chronic maternal stress responses. Regardless of the mechanism and despite the modest effect relative to other risk factors, these findings are provocative in that they suggest that maltreatment not only impacts the health and emotional well-being of individual victims, but may also contribute to intergenerational health disparities.