Prenatal care represents an opportunity to screen for sexually transmitted infections (STIs) for the approximately 500,000 adolescents under the age of 20 who give birth each year.1 Spontaneous abortion, preterm birth, low birth weight, congenital infections, and abnormalities are all associated with STIs in pregnancy. Diagnosis and treatment of STIs, such as Chlamydia trachomatis and Neisseria gonorrhoeae, are important to improve obstetrical outcomes.2,3
Annual STI screening is recommended in this age group, regardless of pregnancy status.4 Nearly half of the 19 million new STIs diagnosed annually in the United States occur among young women and men aged 15 to 24 years. The greatest number of C. trachomatis and N. gonorrhoeae cases are reported among adolescent girls aged 15 to 19 years, with minorities disproportionately affected.5 A recent systematic review supports a rescreening interval of 3 to 6 months for women of all ages who screened positive for C. trachomatis or N. gonorrhoeae, given that median reinfection rates were 14% and 12%, respectively. Age less than 20 years was consistently associated with higher reinfection rates during this follow-up period.6 For those who test positive for an STI at entry to prenatal care, this 3- to 6- month window may occur during pregnancy.
Both the Centers for Disease Control and Prevention (CDC) and The American Congress of Obstetricians and Gynecologists advise STI screening at first prenatal visit and suggest rescreening those at increased infection risk during the third trimester. The CDC specifically advocates for third trimester C. trachomatis rescreening in pregnant women under age 25 and those at increased risk.4 Recent data suggest late pregnancy rescreening may diagnose either reinfection or new STIs.7–9 However, these studies are not specific to adolescents. Furthermore, optimal screening interval and recommended screening frequency among pregnant adolescents are not well-documented.
In this study, we examine the rates of 2 of the most common bacterial STIs, C. trachomatis and N. gonorrhoeae, among a cohort of pregnant adolescents. We report the prevalence of each infection on initial and repeat testing. Among adolescents with repeat prenatal testing, we identify reinfections and new infections.
This is a secondary analysis of a prospective cohort of pregnant adolescents. Patients beginning prenatal care between February 2003 and April 2005 with planned delivery at Washington Hospital Center in Washington, DC, were eligible for enrollment in a comprehensive adolescent parenting program, the Teen Alliance for Prepared Parenting. This program provides comprehensive obstetric and postpartum care, with integrated social work services at an urban academic medical center.10 Patients are seen by attending physician providers or by resident physicians with attending supervision. A substantial proportion of teens who give birth in Washington, DC, deliver at this clinical site. In 2006, 999 births to adolescents aged 15 to 19 years in Washington, DC, were documented; of these, 704 delivered at our hospital.
For study inclusion, individuals had no prior contact with the program, were 18 years of age or less at enrollment, and planned to deliver at the affiliated hospital. Enrolled individuals were excluded from final analysis if they did not complete prenatal care at the affiliated hospital. One person was excluded because results of STI testing were not available. Data for all patients were evaluated through retrospective chart review of medical records.
Routine STI screening was performed at entry to prenatal care, including testing for C. trachomatis and N. gonorrhoeae with either endocervical culture or urine nucleic acid amplification tests. Confirmed diagnosis was noted in the medical record by a provider, and treatment was provided for each STI diagnosis. Patients diagnosed with either were treated according to CDC guidelines. Standard clinic treatment is 1 g oral azithromycin for C. trachomatis and 125 mg intramuscular ceftriaxone for N. gonorrhoeae.
Repeat testing was performed in the third trimester of pregnancy. Some patients had more than 2 screenings for C. trachomatis and N. gonorrhoeae. If diagnosis occurred early in pregnancy, a test-of-cure was performed 4 weeks after diagnosis and treatment. Additional screening was then performed at approximately 36 weeks gestation.
Pertinent demographic characteristics were extracted from the medical record. We calculated percentages of either C. trachomatis or N. gonorrhoeae at initial and repeat screening. Descriptive and univariate statistics were performed with Stata 10 (College Station, TX). Institutional review board approval was obtained through Medstar Research Institute, Washington, DC.
During the study period, 227 pregnant adolescents aged 12 to 18 years were eligible for enrollment in the Teen Alliance for Prepared Parenting. Of those, 146 enrolled, and 125 met inclusion criteria for analysis. Twenty enrolled participants transferred care before delivery, and 1 participant did not have documented results of C. trachomatis or N. gonorrhoeae on medical record review. Nearly two-thirds (63%) of the sample initiated prenatal care before 20 weeks' gestation. The median age at delivery was 17 years. Eighty-four percent were black, 78% were nulliparous, and 88% delivered at term (Table 1).
More than one-fourth of the sample (26%; 32/125) was diagnosed with either C. trachomatis or N. gonorrhoeae infection at entry to prenatal care. Of them, 76% (95/125) had repeat testing for C. trachomatis and N. gonorrhoeae during prenatal care, regardless of initial test results. Reinfection occurred in 11% (10/95), and 7% (7/95) were positive only on repeat testing (Table 2). Nearly one-third of the sample (31%; 39/125) was diagnosed with an infection at least once during pregnancy. Thirty-one percent (10/32) of those who had an STI at initial testing had another infection diagnosed during pregnancy.
Diagnosis of C. trachomatis and N. gonorhoeae was also evaluated separately. For C. trachomatis, 19% (24/125) were diagnosed at entry to prenatal care. Nine percent (9/95) had a recurrent infection, and 4% (4/95) were diagnosed with new C. trachomatis only on repeat testing. Ten percent (13/125) were diagnosed with N. gonorrhoeae at entry to prenatal care. Three percent (3/95) had a recurrent infection, and 4% (4/95) were diagnosed with new N. gonorrhoeae only on repeat testing (Table 2).
One participant was diagnosed with N. gonorrhoeae on initial testing and was then diagnosed with both STIs on repeat testing. Two other participants who were diagnosed with both infections on initial testing were found to have only one on repeat testing. One of these had C. trachomatis and the other had N. gonorrhoeae on repeat testing. No patients who were initially diagnosed with one evaluated STI were diagnosed with only the other on repeat testing.
A test-of-cure was documented as negative in some of these reinfections. Among the 9 who had a second C. trachomatis diagnosis, 3 had a documented negative test-of-cure before diagnosis of reinfection. Among the other 6, the subsequent screening interval occurred between 4 and 14 weeks after initial diagnosis. Among the 3 who had a second N. gonorrhoeae diagnosis, 2 had a documented negative test-of-cure before diagnosis of reinfection.
In this sample of urban pregnant adolescents, just over one-fourth tested positive for either C. trachomatis or N. gonorrhoeae at initial screening, and nearly one-third tested positive at least once during prenatal care.
Sexual risk behavior does not decrease even after an adolescent becomes pregnant. Young pregnant women are one-fifth as likely to use condoms compared with those who have never been pregnant.11–13 According to a recent systematic review of risk behavior among pregnant adolescents and adolescent mothers, between 19% and 39% of pregnant adolescents had at least one STI in pregnancy.12
Urban areas such as Washington, DC have particularly high numbers of STI diagnoses. During the years included in this analysis, 2003 to 2005, the prevalence of C. trachomatis and N. gonorrhoeae were 6.4% and 3.3%, respectively, among 15 to 19-year-old black females in the Washington, DC area.14 The prevalence of each STI we report is substantially higher among pregnant, sexually active females of similar age and ethnicity. Prenatal care may present a critical period to screen, treat, and counsel sexually active adolescents.
The strengths of this study include our high retention rate (86%). Twenty patients who were not analyzed did not complete care at our clinical site, typically due to a change in living situation or insurance that required a transfer of care. Only one participant was followed through delivery and did not have a documented C. trachomatis or N. gonorrhoeae result identified during medical record review.
Our primary limitation is the possibility of persistent infection instead of reinfection with either C. trachomatis or N. gonorrhoeae. Although this cannot be entirely eliminated, concerted clinical efforts were made to ensure appropriate treatment. The 6 patients with suspected C. trachomatis reinfection but no negative test-of-cure had documented prescriptions for azithromycin in the medical record, notations of patient contact, discussion of diagnosis, or copies of mail notification. Similarly, for the single patient with suspected reinfection with N. gonorrhoeae but no negative test-of-cure, the medical record notes a prescription of cefixime. Although it is not a standard clinical protocol to treat N. gonorrhoeae with oral cefixime, this may have been the most effective means of treating that patient. The likelihood of persistent infection after treatment with oral azithromycin, intramuscular ceftriaxone, or oral cefixime for these infections is low, as each is considered effective treatment, with approximately 92% to 95% documented cure rates.4,15 To decrease this persistent infection concern further, expedited sexual partner treatment may be implemented, as it has been shown to be more effective for both N. gonorrhoeae and C. trachomatis treatment when compared to standard partner referral.16
Adolescents without an STI when they began care appeared to benefit from retesting. The importance of screening can be recognized by the fact that approximately one-third of adolescents had either C. trachomatis or N. gonorrhoeae infection at some point during pregnancy. Efforts to develop targeted interventions to reduce acquisition of STIs, in conjunction with routine prenatal care, should be supported and strengthened. Partnering with local health departments and community organizations that reach at-risk adolescents may be an integral component to identifying at-risk pregnant adolescents. These young pregnant women, as well as their sexual partners, must be a priority in STI prevention.
Pregnancy represents an opportune time to intervene for adolescents at risk for STIs. Routine screening at start of prenatal care is an opportunity for counseling on safe sexual behavior, regardless of infection status. Condom use as well as testing and treatment of all sexual partners should be encouraged. Data on sexual behavior were not specifically collected for this study but should be documented during prenatal care. Information about patient's number of sexual partners, sexual activity before and after STI diagnosis, and frequency of condom use may help identify patients at increased infection risk.
Overall, repeat STI screening for all adolescents may be warranted, given the high prevalence of infection, suspected reinfection, and new diagnosis only on repeat testing. We encourage prenatal providers to routinely rescreen pregnant adolescents for STIs, even those not infected at entry to prenatal care.
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