Risk factors associated with preterm birth in the Dominican Republic: a case-control study

Abstract

ObjectivesThis study aimed to identify the risk factors associated with preterm birth, and to determine the prevalence of preterm births in the Dominican Republic.DesignCase-control study.SettingsSeven National Reference Hospitals from different regions of the Dominican Republic.ParticipantsA probabilistic sampling of both cases and controls was performed with a ratio of 2.92:1, and a power analysis was performed with α=0.05, P1=0.5, P2=0.6, and β=0.08, to yield a distribution of 394 cases and 1150 controls. Estimation of gestational age was based on neonatologist reports.Primary outcome measuresA protocol was created to obtain maternal and obstetric information.ResultsThe main risk factors were a family history of premature births (p<0.001, OR: 14.95, 95% CI 8.50 to 26.29), previous preterm birth (p=0.005, OR: 20.00; 95% CI 12.13 to 32.96), advanced maternal age (over 35 years; p<0.001, OR: 2.21; 95% CI 1.57 to 3.09), smoking (p<0.001, OR: 6.65, 95% CI 3.13 to 13.46), drug consumption (p=0.004, OR: 2.43, 95% CI 1.37 to 4.30), premature rupture of membranes (p<0.001, OR: 2.5) and reduced attendance at prenatal consultations (95% CI 6 to 7, Z=−10.294, p<0.001).ConclusionMaternal age greater than 35 years, previous preterm birth, family history of preterm births and prelabour rupture of membranes were independent risk factors for preterm birth. Adolescence, pregnancy weight gain and prenatal consultations, on the other hand, were protective factors for preterm birth. Although the prevalence of premature births in this study was 25%, this could have been biased.