The effects of family functioning on infant birthweight.

A prospective cohort study was undertaken to evaluate the relationship of family functioning to infant birthweight adjusted for length of gestation. The mother's perception of family functioning was assessed at the initial prenatal visit using the Family Adaptability and Cohesion Evaluation Scales (FACES II). All obstetric patients at four family medicine clinics from April 1984 through April 1987 whose initial prenatal visits occurred by the 28th week of gestation were invited to participate; 95% chose to do so. Information was obtained on 833 mother-infant pairs. Listwise deletion on any one variable reduced the sample to 772 with no apparent bias in the dependent or predetermined variables. Twelve percent of the families were considered to be dysfunctional by scoring on the extremes of both the cohesion and adaptability continua of the self-report FACES II questionnaire. Infant birthweight was regressed on length of gestation and other known biomedical, anthropometric, risk-behavior, and sociodemographic determinants, as well as family functioning. Women who perceived their families as dysfunctional were delivered of infants who weighed on the average 126.4 g (95% CI 37.4, 215.4) less than infants born to women from functional families (P = .0055), after adjusting for other known determinants. Family functioning also was found to modify the effects of prepregnancy weight and infant sex on infant birthweight.