Microbicides are substances, like gels or foams, being developed that can be applied before intercourse to prevent transmission of HIV. Research has shown that pregnant women are still at risk of sexual transmission of HIV, and some research has suggested that pregnant women may be at increased risk of HIV infection. Microbicides may also aid in preventing mother-to-child transmission of HIV, because they might be a feasible alternative to oral or intravenous medications in regions where these methods are difficult to implement. In tests on healthy women the vaginal microbicide tenofovir 1% gel has been safe and well tolerated. This study will test the safety of tenofovir 1% gel in healthy, pregnant women and healthy, lactating women.~Participation in this study will last approximately 3 to 10 weeks. Pregnant women will be followed until approximately 2 weeks after delivery of their children, and lactating women will be followed for 3 weeks. Pregnant women will be given either the tenofovir 1% gel or a placebo gel to be applied daily for 7 days. Groups of pregnant women will be further divided according to how late into pregnancy they enroll.~Pregnant women will have study visits at enrollment, 6 days after enrollment, and at delivery. They will also participate in phone assessments 1, 3, and 14 days after enrollment and at delivery.~Lactating women will be given tenofovir 1% gel and have study visits at enrollment and 6 days after enrollment. They will also participate in phone assessments 1, 3, and 14 days after enrollment.~All participants will complete blood tests, physical exams, and assessments of adverse events.
Tenofovir 1% gel is an investigational vaginal microbicide intended to reduce the risk of transmission of HIV. Pregnant women and mothers who have recently given birth often maintain sexual activity, and research has shown that they may be at greater risk of HIV infection during pregnancy. Microbicides may be able to prevent HIV infection during pregnancy, which would also prevent fetal exposure to HIV. This study will test the safety of using tenofovir 1% gel in healthy, pregnant women and healthy, breastfeeding women.