Thanks to various public health campaigns, an increasing number of women and their health care providers are aware of the medication Truvada as PrEP (pre-exposure prophylaxis). But a recent study suggests that pregnant women at risk for HIV and therefore eligible for PrEP, the pill that when taken daily can reduce a woman’s risk of contracting HIV by as much as 90 percent, represent a sorely missed target when it comes to HIV prevention. This is because women who contract the virus during pregnancy are more likely to pass on HIV to their children during gestation and delivery and via breast-feeding.

Results from the study, which were published in the journal Obstetrics & Gynecology, examined a group of pregnant women at high risk for HIV in the Baltimore metropolitan area. Eligibility for PrEP was determined using Centers for Disease Control and Prevention (CDC) guidance.

Heterosexual women not living with the virus were considered eligible if they had a partner living with HIV, a sexually transmitted infection or a high number of sex partners; if they practiced inconsistent or no condom use or engaged in commercial sex work; or if they lived in a high-prevalence area. Because all the women lived in Baltimore, which has the third highest incidence of HIV in the United States, the study excluded this last risk factor.

Among the 1,637 eligible women in the final analysis, all of whom gave birth during the 2012 study year, 10 percent were eligible for PrEP. Seven percent were eligible during their first prenatal visit, and 3 percent became eligible at a later visit, indicating a change in their HIV risk during pregnancy.

Factors associated with PrEP eligibility included being African American, single and having more than one child. Scientists concluded that clinicians should consider these demographic factors when promoting HIV prevention messages. Additionally, researchers pointed out that because pregnant women are more likely than nonpregnant women to believe that their primary male sexual partner is monogamous, they may not be aware of his HIV status or risk behaviors, such as injection drug use and having sex with men. (Less than 30 percent of pregnant women use condoms during sex, according to the researchers.)

Investigators concluded that addressing HIV risk and recommending PrEP to eligible pregnant women only at a first medical visit would not suffice. In high-prevalence areas, each health care consultation with a pregnant woman should include an HIV risk assessment and clinicians should at least broach the subject of PrEP.