Fatores associados à prova de trabalho de parto em primíparas com uma cesárea anterior Factors associated to the trial of labor in primipara women with one previous cesarean section

OBJETIVO: Identificar fatores médicos e não médicos associados à realização da prova de trabalho de parto na segunda gestação de primíparas com uma cesárea anterior. MÉTODOS: Estudo de caso-controle aninhado, com uma análise secundária de dados de um estudo de coorte retrospectivo previamente desenvolvido numa população de mulheres que deu à luz ao primeiro filho em Campinas, no ano de 1985. RESULTADOS: Os principais fatores que estiveram associados à realização da prova de trabalho de parto em 333 gestantes dentre as 1.352 secundigestas com uma cesárea anterior foram: renda familiar mensal inferior a 5 salários-mínimos, seguro-saúde pelo Sistema Único de Saúde, baixa idade materna, presença de rotura de membranas e ocorrência de trabalho de parto no primeiro parto. CONCLUSÃO: Os fatores socioeconômicos são fundamentalmente os principais determinantes da realização da prova de trabalho de parto em secundigestas, com uma cesárea anterior.OBJECTIVE: The purpose of this study was to identify medical and non-medical factors associated to the performance of a trial of labor during the second delivery of women with one previous cesarean section. METHODS: This was a nested case control study, with a secondary data analysis from a retrospective population based cohort study. It was primarily performed on a population of women who had had their first children in Campinas, SP, Brazil, during 1985. The study population was constituted of the 1,352 women of the cohort study who had had their first deliveries by cesarean section and also had their second deliveries no matter when. The group of cases (333 women, almost 25%) was constituted of those women who had a trial of labor during their second deliveries and the control group (1,019 women) of those who had not had it. For each possible associated factor evaluated, the Odds Ratio and its respective 95% Confidence Interval were calculated. For the ordered categorical variables, the chi² for trend was also calculated. Finally, a non conditional multivariate regression analysis was performed, identifying the significant factors and then estimating their adjusted Odds Ratio. RESULTS: The main factors associated with the trial of labor in this situation were a low monthly family income, having public medical insurance by the national health system, a low maternal age, the occurrence of rupture of membranes during the second delivery, and having been in childbirth during the first delivery. CONCLUSION: It is concluded that the main determinants for a trial of labor among primipara women with one previous cesarean section were basically social and economic factors, rather than medical ones