PRENATAL-CARE AND PREVENTION OF PRETERM BIRTH - A CASE-CONTROL STUDY IN SOUTHERN SPAIN

The value of prenatal care is controversial and difficult to establish . A national policy for improving perinatal outcomes was proposed and applied throughout Andalusia (Southern Spain) in 1984. Here we report the results of an evaluation of this health care program as regards th e prevention of preterm delivery. Effectiveness of prenatal care was a ssessed on the basis of two case-control studies in a hospital setting ; one performed before the program was implemented (1981-1982) and the second one six years after the program began (1990-1993). A total of 229 cases and 395 controls for the period 1981-1982, and 207 cases and 381 controls for 1990-1993 were selected. Prenatal care was assessed based on the number of prenatal care visits, the date of the first vis it, and an American composite index adjusting for gestational age. Mul tiple-factor adjusted odds ratios and their 95% confidence intervals ( CI) were estimated using unconditional logistic regression analysis. T he use of prenatal care significantly improved across time: the propor tion of women receiving no prenatal care decreased from over 30% to le ss than 5%, and the proportion of women starting prenatal care in the first trimester for 1990-1993 was three times greater than the figure for 1981-1982. In the 1981-1982 case-control study, the date of first visit and the composite index were shown to be unrelated to preterm bi rth risk; and the number of visits yielded a significant association, although no definite trend could be established. In the 1990-1993 case -control study, a clear and significant relationship was observed betw een the number of prenatal care visits, the trimester of the first vis it, and the adequacy of care according to the composite index. This la tter variable, reflecting a more stringent standard of prenatal care, was selected by a stepwise logistic regression analysis as the best pr edictor for preterm birth risk. The results suggest that the present A ndalusian program helps prevent preterm delivery. Nonetheless, its min imum standards should be raised to further decrease preterm birth risk .