Objectives: To analyze the relation between perinatal variables (gestational, neonatal, demographic, and social) at time of delivery. To evaluate differences between rural and urban areas --and differences between social status within these areas-- as an approach to studying health inequality. To identify variables associated with the risk of prematurity and low birth weight from onset of pregnancy.
Methods: A retrospective study was made of deliveries in a 4-year period (1993-1996) in a health-care district of the province of Cáceres (Spain) (population: 176,511 inhabitants). Data were obtained from hospital records (N = 5922 deliveries). Gestational (mother's age, multiparity), neonatal (sex, birth weigh, weeks of gestation, twin birth), and sociodemographic variables (mother's place of residence and social rank) were studied. A logistical regression analysis was made to identify the main risk factors.
Results: The percentage of infants with birth weight less than 2800 g (16.92%) or less than 2500 g (7.80%), and of preterm births (6.16%) in the health-care district of Cáceres were higher than those reported for other studies made in Spain and elsewhere. The risk of low birth weight (<2800 g) was greater for twin births (OR = 16.50; IC 95%: 9.67-28.15); female infants (OR = 1.36; IC 95%: 1.19-1.56), adolescent mothers (<20 years: OR = 1.54; IC 95%: 1.14-2. 09), older mothers (>35 years: OR = 2.12; IC 95%: 1.41-3.17), and first pregnancies (OR = 1.25, IC 95%: 1.09-1.44). The mother's social status was a risk factor for urban marginal groups compared with non-marginal groups (OR = 1.43, IC 95%: 1.12-1.82). The risk of preterm birth depended mainly on the mother's age and was greater in adolescents (OR = 1.84, IC 95%: 1.17-2.89) and older women (OR = 3. 08, IC 95%: 1.81-5.24), as well as for twin births (OR = 10.47; IC 95%: 6.49-16.89). Women in marginal urban groups had the highest rates of multiple pregnancies and adolescent pregnancies. Women in non-marginal urban areas had the highest rate of first pregnancies in older women. Women in rural areas showed intermediate characteristics.
Conclusions: The percentage of low-birth-weight or preterm newborns and of adolescent mothers was greater in women of lower socioeconomic level. The greatest differences in perinatal variables were observed in urban areas (marginal vs. non-marginal groups) and between regions and countries.