Benefits of PrEP as an Adjunctive Method of HIV Prevention During Attempted Conception Between HIV-uninfected Women and HIV-infected Male Partners

Abstract

Background: Data on effectiveness of preexposure prophylaxis (PrEP) for human immunodeficiency virus (HIV)-uninfected women attempting conception with HIV-infected male partners are limited to observational studies.

Methods: To explore the benefits of PrEP for conception, we developed a model to estimate the average annual probability of a woman remaining HIV-uninfected and having a child ("successful" outcome) via condomless sex with an HIV-infected male. The outcome likelihood is dependent upon parameters defining HIV-1 infectivity. We simulated 2 scenarios: optimal (condomless sex acts limited to the ovulation window), and suboptimal (acts not limited to ovulation).

Results: In the optimal scenario when the male is on antiretroviral therapy (ART), the average annual probability of the successful outcome is 29.1%, increasing to 29.2% with the addition of PrEP (P = .45). In the suboptimal scenario, the probability is 26.8% with ART alone versus 27.3% with ART/PrEP (P < .0001). Older maternal age reduces the probability of success in both scenarios, particularly after age 30.

Conclusions: In our model, PrEP provides little added benefit when the HIV-infected male partner is on ART, condomless sex is limited to the ovulation window, and other modifiable transmission risks are optimized. Older female age decreases the probability of success by increasing the number of condomless sex acts required for conception.

Keywords: antiretroviral therapy; mathematical model; preexposure prophylaxis; safer conception.

Figure 1.

Average annual probabilities of successful and unsuccessful outcomes in the optimal scenario (condomless sex is limited to the window of ovulation) for each of the 4 clinical interventions modeled. A, Probability of a successful outcome (female remains HIV-uninfected and has a child). B, Probability of an unsuccessful outcome (female becomes HIV-infected and does not have a child). Within each panel, all pairwise comparisons of means are statistically different at the P < .0001 level except for ART compared to PrEP and ART in the successful outcome (29.1% versus 29.2%) Lines represent one standard deviation above and below the mean. Abbreviations: ART, antiretroviral therapy; HIV, human immunodeficiency virus; *NS, nonsignificant; PrEP, preexposure prophylaxis.

Figure 2.

Average annual probabilities of successful and unsuccessful outcomes in the suboptimal scenario (condomless sex occurs throughout the month and is not limited to the window of ovulation) for each of the 4 clinical interventions modeled. A, Probability of a successful outcome (female remains HIV-uninfected and has a child). B, Probability of an unsuccessful outcome (female becomes HIV-infected and does not have a child). Within each panel, all pairwise comparisons of mean are statistically different at the P < .0001 level. Lines represent one standard deviation above and below the mean. Abbreviations: ART, antiretroviral therapy; HIV, human immunodeficiency virus; PrEP, preexposure prophylaxis.

Figure 3.

Comparison of average annual probabilities in the optimal (condomless sex limited to the window of ovulation) versus suboptimal (condomless sex occurs throughout the month) scenarios for each of the 4 clinical interventions modeled. A, Comparison of optimal (dark gray bars) versus suboptimal (light gray bars) scenarios for the annual probability of the successful outcome of the female remaining HIV-uninfected and having a child. B, Comparison of optimal (dark gray bars) versus suboptimal (light gray bars) scenarios for the annual probability of the unsuccessful outcome of the female becoming HIV-infected and not having a child. Within each panel, the comparison between optimal and suboptimal for each strategy is statistically significant at the P < .0001 level. Abbreviations: ART, antiretroviral therapy; HIV, human immunodeficiency virus; PrEP, preexposure prophylaxis.

Figure 4.

The annual probability of each outcome (successful and unsuccessful) for optimal and suboptimal scenarios when different clinical interventions are modeled (PrEP vs ART vs PrEP and ART), by maternal age. A, Optimal scenario, successful outcome. B, Optimal scenario, unsuccessful outcome. C, Suboptimal scenario, successful outcome. D, Suboptimal scenario, unsuccessful outcome. Abbreviations: ART, antiretroviral therapy; PrEP, preexposure prophylaxis.