Genitourinary tract infections in pregnancy and low birth weight: case-control study in Australian aboriginal women.

OBJECTIVE: To investigate the association between genital and urinary tract infections in pregnant Aboriginal women and low birth weight. DESIGN: Retrospective case-control study controlling for potential confounding variables. SETTING: Western Australia from 1985 to 1987. SUBJECTS: All Aboriginal women (n = 269) who had given birth to singleton infants weighing 2250 g or less (cases), and 269 randomly selected Aboriginal women who had given birth to singleton infants weighing 3000 g or more (controls). MAIN OUTCOME MEASURES: Proportions of women in case and control groups who had had genital and urinary tract infections; odds ratios for low birth weight when genitourinary tract infection was present; population attributable fraction of low birth weight to genitourinary tract infection. RESULTS: At the time of delivery 51% of women in the case group (109/215) had genitourinary tract infections compared with 13% of controls (35/266). After controlling for potential confounding variables the odds ratio for giving birth to infants weighing 2250 g or less when genitourinary tract infection was present was 4.0 (95% confidence interval 2.3 to 7.0). The proportion of infants with low birth weight attributable to genitourinary tract infection in the whole population of Aboriginal women was 32% (95% confidence interval 17% to 49%). CONCLUSIONS: There was a strong association between low birth weight and the presence of genitourinary tract infections in Aboriginal women both during pregnancy and at the time of delivery. A community intervention trial of screening and treatment of genitourinary infections in this population is recommended.