Female adolescents who have a sexually transmitted disease (STD) are more likely to have recently acquired a new sex partner than their sexually active peers who do not have an STD, according to a longitudinal study of teenagers receiving care at public health clinics in Connecticut.1 One in four adolescents acquired a new partner during the 12-month follow-up, and these women had three times as high odds of receiving a new chlamydia or gonorrhea diagnosis as others. Adolescents with a new partner were less likely than those with an established partner to know their partner’s history of STDs and of sex with others. A second study by the same team of researchers using the same data indicates that teenagers who have recently given birth are at greater risk for an STD than their peers who have not given birth.2 The STD infection rate was stable for teenagers who did not give birth during the follow-up period, but increased between six and nine months postpartum among females who gave birth, especially among those who acquired new partners.
Adolescents with New Sex Partners
To examine associations between the acquisition of new sex partners and STD risk in young women, the researchers recruited females between the ages of 14 and 19 from health clinics serving predominantly low-income populations in New Haven, Hartford and Bridgeport, Connecticut. Between 1998 and 2000, adolescents who had had sexual intercourse, had not given birth, were HIV-negative and were receiving gynecologic or obstetric care at one of the 10 participating clinics were invited to participate in face-to-face interviews. The interviews, which lasted 60-90 minutes, were repeated six and 12 months later. At each interview, the researchers asked about sexual history, sexual risk behavior, partnership characteristics and other factors, and collected urine samples to be tested for chlamydia and gonorrhea. To determine if a new partner was acquired, they asked if participants’ current partner was the same one as at last interview.
Of the 411 adolescents in the sample, 44% were black and 42% Hispanic. Eighty-three percent were in high school or had graduated. On average, the adolescents were 17.3 years old, had been 14.5 years old at first intercourse and had had 4.1 lifetime partners. The vast majority of young women who were currently sexually active reported having had only a single sex partner in the past 30 days (97%). Of the 363 adolescents who completed interviews at six or 12 months, 24% acquired a new partner during follow-up; 15% of those with STD results from the follow-up period had a new chlamydia or gonorrhea infection diagnosed.
A significantly greater proportion of those with a new partner than of those without a new partner had an STD (27% vs. 12%). New partner acquisition was more common among 14-16-year olds than among older adolescents (31% vs. 19%); more common among those who had been 14 or younger at first intercourse than among those who had been older (34% vs. 16%); and more common among those who had used alcohol or drugs before sex in the past 30 days than among those who had not (42% vs. 20%). A greater proportion of nonpregnant than pregnant adolescents acquired a new partner (31% vs. 17%), and the same was true for adolescents who had not had a pregnancy in the past compared with those who had (28% vs. 18%).
A multivariate analysis showed that adolescents with an STD were significantly more likely than those without an STD to have a new partner (odds ratio, 3.0). Other factors associated with the acquisition of a new partner were younger age (1.8), younger age at first intercourse (2.7) and alcohol or drug use before sex in the past 30 days (2.7).
Twenty-two percent of adolescents in new partnerships said they did not know their partner’s STD history, compared with 8% of those in established partnerships. Twenty-three percent of those with new partners said their partner had had sex with someone else in the past six months, and 20% did not know if he had, compared with 10% and 8%, respectively, of those with established partners. Adolescents with new partners were significantly more likely than their peers in established relationships to say they had used alcohol or drugs before sex in the past 30 days (38% vs. 20%) and were less likely to say they had had unprotected intercourse in the past 30 days (35% vs. 48%).
The findings suggest that the acquisition of a new partner is an important predictor of STD, the authors conclude. To help reduce STD infections in adolescents, clinicians "should ascertain if their adolescent patients are in new relationships and, if so, test them and their partners for STDs," they write.
Adolescents in the Postpartum Period
In the second study, the researchers compared data for the 203 adolescents who were pregnant at baseline (whose initial interview took place during the third trimester) and the 208 nonpregnant adolescents. At baseline, significantly greater proportions of pregnant adolescents than of others had dropped out of school (23% vs. 11%), said they had been older than 14 at first intercourse (58% vs. 47%) and had had a previous pregnancy (53% vs. 24%). All previous pregnancies had ended in spontaneous or induced abortion; the study criteria excluded females who had already given birth.
For adolescents in the postpartum period, the proportion with new STD infections increased between the six- and 12-month follow-up visits from 7% to 14%; by contrast, the rate of new infections was stable among their peers who had not given birth (8-9%). In a logistic regression analysis of a subgroup of teenagers with STD test results at baseline, six and 12 months (126 pregnant and 133 not pregnant at baseline), the prevalence of infection was 1.9 times as high in adolescents who were nine months postpartum as in adolescents who had not been pregnant at baseline. STD prevalence did not differ between the groups in the six months preceding the baseline interview; approximately one-third of both pregnant and nonpregnant adolescents had had a diagnosis of chlamydia or gonorrhea, according to a review of medical and of state health department records.
Chi-square testing pointed to two potential predictors of postpartum STD: the acquisition of a new partner (reported by 45% of postpartum adolescents with STDs vs. 11% of STD-free adolescents) and a history of two or more sex partners per year of sexual activity (77% vs. 52%). Age, race, education and condom use at last sex were not significantly related to the likelihood of a postpartum STD diagnosis in adolescents pregnant at baseline.
Results of multivariate analysis confirmed these findings. Adolescents in the postpartum period who had a new partner were 6.3 times as likely as those without a new partner to have an STD; those with a higher average number of sex partners per year of sexual activity were 3.0 times as likely to have an STD as were those with a lower average number of partners.
The findings suggest that clinicians can target STD prevention messages to high-risk adolescents by focusing on those in new sex partnerships or in the postpartum period, the authors conclude. "Routine prenatal and postpartum care provide unique opportunities to promote condom use and other risk reduction interventions among adolescents," they write. —T. Tamkins
1. Niccolai LM et al., New sex partner acquisition and sexually transmitted disease risk among adolescent females, Journal of Adolescent Health, 2004, 34(3):216-223.
2. Ickovics JR et al., High postpartum rates of sexually transmitted infections among teens: pregnancy as a window of opportunity for prevention, Sexually Transmitted Infections, 2003, 79(6):469-473.