Objective: Although the state of the science is inconclusive regarding the impact of domestic violence on birth weight, abuse has been linked consistently to maternal health risks. Previous studies have been predominantly of low-income pregnant women, who are more likely to carry these risks. This study explored the impact of intimate partner violence on the health of mothers and newborns in a large and economically diverse sample, to enable nurses to distinguish the health needs of low-income and higher-income abused pregnant women.
Design: After prospectively instituting prenatal domestic violence screening by clinicians at study sites, records were reviewed retrospectively and a case control design was used for data analysis.
Population, Sample, Setting, Years: The target population for study was all prenatal clients at 13 eastern Massachusetts prenatal care sites from 1996-1999. Data were extracted from records of all clients in the target population. The sample for the present analysis consisted of the 2049 women who were screened for abuse, whose pregnancies continued beyond 20 weeks gestation, and for whom birth outcome data were available. Racial and ethnic background was 54% European-American, 22% Latina, 9% African-American, 6% Asian, and 8% other. Socioeconomic status was represented by 55% public health care funding and 45% private insurance. Average maternal age was 27 (range 13-45) and education was 11.7 years (range 0-20).
Variables Studied Together: Recent intimate partner abuse was measured by the Abuse Assessment Screen. Birth outcomes included low birth weight (<2500g), prematurity (gestational age <37 weeks), and low Apgar score (<7 at 5 minutes after birth). Public vs. private health insurance was used as a proxy for income level. Marital status, maternal age, education, racial origin, and parity were analyzed as covariates. The risk factors for low birth weight as defined by the Institute of Medicine were analyzed as maternal morbidities and included substance abuse, poor nutrition, and a range of medical and obstetrical complications.
Methods: Prenatal care providers were trained in use of the 5-item Abuse Assessment Screen (AAS) and screened prenatal clients at a regular prenatal visit. Trained project staff and students retrieved medical records after delivery and extracted data for all clients at each site for the 3-year study period. Frequencies, descriptive statistics, t-tests, crude and stratified odds ratios, and logistic regression analyses were used to analyze the data.
Findings: Seven percent of the sample (139 of 2047) reported abuse within the past year. Abused women were more likely to have public health insurance, be single, and have less than 12 years education, but abuse was not related to racial/ethnic background or parity. Abused women were younger than non-abused (24.6 vs.27.2 years), started prenatal care later (12.3 vs. 11 weeks), and had infants with lower birth weights (3267g vs. 3381g). However, when dichotomized birth outcomes were examined, abuse did not affect the odds of low birth weight, preterm delivery, or low 5-minute Apgar scores.
Abuse increased the odds of 11 maternal health risks and morbidities: poor nutrition, low weight gain, poor obstetrical history, infection, bleeding, hyperemesis, smoking, alcohol, and illicit drug use, preterm labor, and hypertension. In separate logistic regressions for the low-income group, after controlling for single marital status and low education, abuse increased the odds of hyperemesis, smoking, alcohol and drug use, poor nutrition, and hypertension. In privately insured women, abuse increased the odds of vaginal bleeding before 24 weeks and poor nutrition.
Conclusions: Recent intimate partner violence did affect infant birth weight but did not increase the clinically important risk of birth weight below 2500 grams. Abuse did, however, increase a number of obstetrical risks and had a more deleterious effect on low-income women than on those with private health insurance.
Implications: The link between abuse and low birth weight seen in other samples may be a result of the impact of abuse on maternal health and lifestyle factors. This impact may take different forms in different socioeconomic groups. Low-income women may have fewer material and coping resources with which to buffer the stressful effects of abuse, leading to substance abuse and other unhealthy coping responses. Poor nutrition may be a marker for abuse in both low- and higher-income women. Nurses can use this knowledge both to address health needs specific to abused low- and higher-income women, and to explore the possibility of intimate partner violence with pregnant women who show a pattern of stress-related adverse health behaviors.
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