Assessment of the Association of Chlamydia trachomatis Infection and Adverse Perinatal Outcomes with the Use of Population-Based Chlamydia Case Report Registries and Birth Records.

OBJECTIVE: We assessed the relationship between Chlamydia trachomatis (CT) infections identified during pregnancy and adverse perinatal birth outcomes (including premature rupture of membranes, preterm delivery, and low birthweight) by matching CT reports and birth records.
METHODS: We merged California birth records from 1997, 1998, and 1999 with California CT reports from the same years to determine the proportion of birth records matched to a female CT report, using maternal last name, first name, date of birth, and county of residence. We used logistic regression to assess the crude and adjusted association between a CT report less than 10 months before the birth record date and premature rupture of membranes, preterm delivery, and low birthweight. These results were adjusted for age, race/ethnicity, level of education, and prenatal care.
RESULTS: Of 675,786 birth records and 101,296 female CT reports, 14,039 women had a CT case report and a birth record; 10,917 birth records (1.6%) were matched to a CT report during pregnancy, and 10,940 (10.8%) of CT reports were matched to a birth record date 10 months after date of diagnosis/report. For premature rupture of membranes, the adjusted odds ratio (AOR) was 1.2, 95% confidence interval (CI) 1.0, 1.3; for low birthweight, the AOR was 1.2, 95% CI 1.1, 1.3. The reduction in birthweight associated with prenatal CT infection was 31.7 grams.
CONCLUSIONS: The increased risk of adverse perinatal outcomes associated with prenatal CT infection supports current prenatal CT screening guidelines. Matching of surveillance and vital statistics data sources was an efficient method to assess this association.