Psychosocial predictors of low birthweight: a prospective study

Objective To examine the role of psychosocial risk factors for low birthwei ght. Design A prospective study. Setting Obstetric outpatient clinics of the University Hospital Vrije Unive rsiteit, Amsterdam. Participants Three hundred and ninety-six nulliparous women. Methods Questionnaires on background variables, daily stressors, psychologi cal and mental wellbeing, social support and work factors were completed by the women in the first, second and third trimester of pregnancy. Low birth weight for gestational age was defined at different cut off points: 1. less than or equal to 10th customised birthweight centile (n = 69); 2. less tha n or equal to 5th customised birthweight centile (n = 54); 3. < 3rd customi sed birthweight centile (n = 35); and 4. less than or equal to the 10th Dut ch birthweight centile (n = 40). Multivariate logistic regression was appli ed and the results were expressed in odds ratios and their 95% confidence i ntervals. Results When the cut off level was defined less than or equal to 5th and < 3rd customised centile, the number of daily stressors in the first trimeste r was a statistically significant risk factor (OR 1.04, 95% CI 1.01-1.07 an d OR 1.04, 95% CI 1.01-1.08). No significant psychosocial risk factors coul d be identified when low birthweight for gestational age was defined less t han or equal to the 10th customised birthweight centile. When low birthweig ht for gestational age was defined less than or equal to the 10th Dutch bir thweight centile, number of hours housekeeping per week in the first trimes ter (OR 1.59, 95% CI 1.03-2.46), low subjective severity rating of daily st ressors in the first trimester (OR 0.41, 95% CI 0.17-0.97) and depressive m ood in the first trimester (OR 1.12, 95% CI 1.01-1.24) were statistically s ignificant psychosocial risk factors after controlling for maternal weight and height, number of cigarettes smoked per day and educational level. Conclusions In the first trimester of pregnancy maternal psychosocial facto rs are associated with an increased risk of low birthweight. The specific p sychosocial risk factors found were different when the definition of low bi rthweight was changed. Therefore, in this field of research, we suggest use of the most valid outcome measure for low birthweight, being the customise d birthweight centiles.