Serologic evidence of Chlamydia trachomatis infection and risk of preterm birth.

OBJECTIVE

To determine whether serologic evidence of Chlamydia trachomatis during pregnancy is a risk factor for preterm delivery (before 37 weeks' gestation).

DESIGN

Chart review.

SETTING

Antenatal clinics associated with a teaching hospital.

PATIENTS

A group of 103 unselected consecutive patients presenting for routine prenatal care.

OUTCOME MEASURES

Pregnancy outcome and C. trachomatis serologic status.

RESULTS

A total of 21 women (20%) were found to be seropositive for IgG antibodies to C. trachomatis. They were similar to the seronegative women with respect to maternal age, parity, history of preterm birth, obstetric or medical problems, smoking status, history of drug abuse, educational status and psychosocial stressors. The seropositive women were significantly more likely than the seronegative women to have a preterm birth (24% [5/21] v. 7% [6/82]i p = 0.029, odds ratio 3.96, 95% confidence interval 1.08 to 14.57), an infant with a lower mean gestational age at birth (262 [standard deviation (SD) 19] days v. 273 [SD 15] days; p = 0.0052) and an infant with a lower mean birth weight (3125 [SD 692] g v. 3473 [SD 696] g; p = 0.0434). The positive predictive value of a seropositive result for preterm birth was 31% (5/16); the negative predictive value of a seronegative result for preterm birth was 8% (6/76).

CONCLUSION

Women with serologic evidence of C. trachomatis may be at risk for preterm birth. Further study is required to determine whether serologic testing for C. trachomatis should be a routine part of prenatal care.