Trichomonas vaginalis associated with low birth weight and preterm delivery. The Vaginal Infections and Prematurity Study Group.

BACKGROUND: Several studies have suggested that pregnant women infected with Trichomonas vaginalis may be at increased risk of an adverse outcome.

GOAL: To evaluate prospectively the association between T. vaginalis and risk of adverse pregnancy outcome in a large cohort of ethnically diverse women.

STUDY DESIGN: At University-affiliated hospitals and antepartum clinics in five United States cities, 13,816 women (5,241 black, 4,226 Hispanic, and 4,349 white women) were enrolled at mid-gestation, tested for T. vaginalis by culture, and followed up until delivery.

RESULTS: The prevalence of T. vaginalis infection at enrollment was 12.6%. Race-specific prevalence rates were 22.8% for black, 6.6% for Hispanic, and 6.1% for white women. After multivariate analysis, vaginal infection with T. vaginalis at mid-gestation was significantly associated with low birth weight (odds ratio 1.3; 95% confidence interval 1.1 to 1.5), preterm delivery (odds ratio 1.3; 95% confidence interval 1.1 to 1.4), and preterm delivery of a low birth weight infant (odds ratio 1.4; 95% confidence interval 1.1 to 1.6). The attributable risk of T. vaginalis infection associated with low birth weight weight in blacks was 11% compared with 1.6% in Hispanics and 1.5% in whites.

CONCLUSIONS: After considering other recognized risk factors including co-infections, pregnant women infected with T. vaginalis at mid-gestation were statistically significantly more likely to have a low birth weight infant, to deliver preterm, and to have a preterm low birth weight infant. Compared with whites and Hispanics, T. vaginalis infection accounts for a disproportionately larger share of the low birth weight rate in blacks.