Predicting pregnancy risk in women attending an STD clinic.

Background: Although sexually transmitted disease (STD) clinics focus mainly on STD treatment and prevention, women attending these clinics are also at high risk for pregnancy.

Goal: To evaluate the relationship between certain demographic and behavioral characteristics and the probability of pregnancy in women attending an urban STD clinic.

Study Design: Non-contraceptive-using women in an STD clinic-initiated randomized controlled contraception study (n = 877) were interviewed at baseline, and incident pregnancies within 1 year of enrollment were measured. Association between baseline demographic and behavioral characteristics with incident pregnancy was assessed by chi-square analysis, and logistic regression was used to assess factors associated with an incident pregnancy.

Results: Among the 673 women (76.7%) for whom follow-up pregnancy information was available, 220 (32.7%) incident pregnancies occurred within 1 year. By logistic regression controlling for study assignment, incident pregnancy was associated with age < or =19 years (odds ratio [OR], 2.8; 95% CI: 1.5-5.2), previous abortion (OR, 3.1; 95% CI: 1.7-5.4), frequency of sexual encounters of at least once a week (OR, 1.8; 95% CI: 1.2-2.6), and having a chlamydial infection at the time of enrollment (OR, 1.8; 95% CI: 1.0-3.2). With a combination of demographic and behavioral characteristics correlated by univariate analysis with incident pregnancy (i.e., age < or =19 years, nonwhite race, high school/general equivalency diploma or less education, previous pregnancy, no use of birth control with last intercourse, sex at least once a week, previous abortion, > or =3 partners within the past month, and <17 years of age at first pregnancy), the cumulative risk of pregnancy with 6 or more of the 9 characteristics was 51%, compared with 25.6% for women with < or =5 characteristics.

Conclusion: For this STD clinic population, a combination of demographic and behavioral characteristics was useful when combined for identifying a subgroup of women at higher risk for subsequent pregnancy. Targeted intervention by STD care providers should include the provision for both pregnancy and STD prevention counseling.