Prospective randomised controlled trial of an infection screening programme to reduce the rate of preterm delivery.

OBJECTIVE To evaluate whether a screening strategy in pregnancy lowers the rate of preterm delivery in a general population of pregnant women. DESIGN Multicentre, prospective, randomised controlled trial. SETTING Non-hospital based antenatal clinics. PARTICIPANTS 4429 pregnant women presenting for their routine prenatal visits early in the second trimester were screened by Gram stain for asymptomatic vaginal infection. In the intervention group, the women's obstetricians received the test results and women received standard treatment and follow up for any detected infection. In the control group, the results of the vaginal smears were not revealed to the caregivers. MAIN OUTCOME MEASURES The primary outcome variable was preterm delivery at less than 37 weeks. Secondary outcome variables were preterm delivery at less than 37 weeks combined with different birth weight categories equal to or below 2500 g and the rate of late miscarriage. RESULTS Outcome data were available for 2058 women in the intervention group and 2097 women in the control group. In the intervention group, the number of preterm births was significantly lower than in the control group (3.0% v 5.3%, 95% confidence interval 1.2 to 3.6; P = 0.0001). Preterm births were also significantly reduced in lower weight categories at less than 37 weeks and <or= 2500 g. Eight late miscarriages occurred in the intervention group and 15 in the control group. CONCLUSION Integrating a simple infection screening programme into routine antenatal care leads to a significant reduction in preterm births and reduces the rate of late miscarriage in a general population of pregnant women.