Interrupted time series designs are frequently employed to evaluate program impact. Analysis strategies to determine if shifts have occurred are not well known. The case where statistical fluctuations (errors) may be assumed independent is considered, and a segmented regression methodology presented. The method discussed is applied to the assessment of changes in local and state perinatal postneonatal mortality to identify historical trends and will be used to evaluate the impact of the North Carolina Regionalized Perinatal Care Program when seven years of postprogram mortality data become available. The perinatal program region is contrasted with a control re-

We investigated whether work-related psychologic stress-defined as work characterized by both high psychologic demands and limited control over the response to these demandsincreases a woman's risk of delivering a preterm, low birthweight infant.We studied 786 employed pregnant women included in the National Longitudinal Survey of Labor Market Experience, Youth Cohort (NLSY), a nationally representative sample of 12,686 young adults. Data concerning work status, job title, and other factors affecting pregnancy outcome were obtained from the NLSY. Assessment of job experience was based on job title, using an estab-

BACKGROUND: Although maternal employment is considered a risk factor for low birthweight (LBW), the manner in which employment might affect birthweight is poorly understood. In this analysis, selected characteristics of employment during pregnancy were examined for effects on pregnancy outcomes. METHODS: Work characteristics included the number of hours per week, physical activities, and environmental conditions. The outcomes of interest were fetal growth retardation (less than 2500 grams at term) and preterm delivery (less than 37 weeks). The study population consisted of 2711 non-Black, married mothers who participated in the 1980 National Natality Survey (NNS). The NNS data were merged with data from the 1977 revision of The Dictionary of Occupational Titles (DOT) from which measures of occupational physical activities and environmental exposures were obtained. Logistic regression was used in the analysis. RESULTS: Those who worked 40 or more hours per week were more likely than women who worked fewer hours to have a low birthweight delivery at greater than or equal to 37 weeks. No physical or environmental characterics of work were associated with low birthweight or preterm delivery. CONCLUSIONS: Non-Black married American women may face a risk of delivering low-birthweight babies at or near term only if they work 40 or more hours each week. However, the lack of risk associated with other characteristics of work may be a function of measurement error in the DOT data source or of low levels of exposure in the analysis population.

Although many women work during pregnancy, the effect of maternal job experience on pregnancy outcome is controversial. We investigated whether work-related physical exertion increases a woman's risk of delivering a preterm, low birthweight infant. We studied 773 employed, pregnant women included in the National Longitudinal Survey of Labor Market Experience, Youth Cohort (NLSY), a nationally representative sample of young adults. Data concerning work status, job title during pregnancy, and other factors affecting the outcome of pregnancy were obtained from the NLSY. Assessment of physical exertion was based on job title, using an established catalogue of occupational characteristics. Women in jobs characterised by high physical exertion experienced a higher rate of preterm, low birthweight delivery, defined as maternal report of delivery more than 3 weeks early and birthweight under 2,500 g (adjusted RR = 5.1, 95% CI = 1.5, 17.7). These findings support a policy of limiting work-related physical exertion during pregnancy.

Effects of early and extended postpartum contact and paraprofessional home visits on maternal attachment, reports of child abuse and neglect, and health care utilization were determined by random assignment of 321 low-income women to intervention or control groups immediately after delivery. Observations of maternal attachment were made at four months and 12 months. Hospital, health and welfare agency records, and interviews were used to determine reports of child abuse and neglect and health care utilization. After establishing a control for maternal background variables, early and extended contact explained statistically significant but small amounts of variance in several of the attachment measures. There were no statistically significant effects of the home visit interventions on maternal attachment, and neither intervention was related to reports of child abuse and neglect and health care utilization. Although the study supported earlier findings that early and extended contact has a significant effect, additional interventions are needed to support mother-infant attachment.