There are many biological changes that occur during pregnancy, some of which may affect the way HIV medications are absorbed, distributed and removed within the body. Some medications have been used for HIV treatment during pregnancy, but little is known about how pregnancy affects the class of drugs being used in this study. To participate in this study, patients must be receiving 600mg of TMC114 (darunavir) taken with 100mg ritonavir twice daily or 800mg of TMC114 (darunavir) with 100mg of ritonavir once daily or 800 mg of darunavir taken with 150mg of cobicistat taken once daily or 200mg of TMC125 (etravirine) (with or without darunavir/ ritonavir) taken twice daily or 25mg of TMC278 (rilpivirine) taken once daily plus additional antiretroviral drugs needed to construct an active antiretroviral regimen. Darunavir and ritonavir, darunavir and cobicistat, etravirine, or rilpivirine will be supplied to study participants. Darunavir and ritonavir are human immunodeficiency virus (HIV) protease inhibitors (PIs); cobicistat is a pharmacoenhancer which boosts the levels of darunavir but has no anti-HIV activity; etravirine and rilpivirine are non-nucleoside reverse transcriptase inhibitor (NNRTI) of HIV. Twelve-hour or twenty four-hour blood sampling will be done for each patient at each of three study visits: Visit 4 (2nd trimester), Visit 5 (3rd trimester), and Visit 8 (6-12 weeks postpartum). Eight blood draws will be taken during each visit: One prior to intake of study medication, and one for each of seven post-dose sampling time-points (hours 1, 2, 3, 4, 6, 9 and 12). The study is designed primarily to examine the pharmacokinetics of darunavir/ritonavir (darunavir/r), darunavir/ cobicistat, etravirine or rilpivirine during the second and third trimesters of gestation, as well as postpartum. Pharmacokinetics measures how the body absorbs, distributes and excretes medication. The study will also examine any changes in anti-viral activity during pregnancy, and the postpartum period. It will note any safety and tolerability of the medications used by the mother, and will measure the level of darunavir/ritonavir, darunavir/ cobicistat, etravirine or rilpivirine in the newborn's cord blood at the time of delivery; outcomes for both mother and child will be assessed as well. During the treatment period, patients will be seen at regular visits in the clinic, where the investigator will assess the patient's medical condition, any Adverse Events and study drug compliance. Laboratory evaluations for efficacy and safety will be done at regular visits as well as blood pressure monitoring. Up to forty-eight (48) HIV positive pregnant women will participate in this study. Study enrollment will be closed once 12 evaluable patients taking darunavir/ritonavir once daily, 12 evaluable patients taking darunavir/cobicistat once daily, 12 evaluable patients taking darunavir/ritonavir twice daily, 12 evaluable patients taking etravirine taking twice daily and 12 evaluable patients taking rilpivirine once daily have been enrolled. The study will be conducted at approximately 14 research centers in the United States and 1 in Puerto Rico. In order to participate, patients must be pregnant for 13-24 weeks. The primary purpose (or outcome) of the study is to assess the influence of pregnancy on the pharmacokinetics of darunavir/ritonavir, darunavir/ cobicistat, etravirine or rilpivirine during the second and third trimesters of gestation, as well as postpartum. Darunavir: One 600 mg or two 300 mg tablets taken twice daily by mouth (two or four tablets a day total). Ritonavir: 100mg tablet taken twice daily by mouth (two tablets a day total), together with darunavir. Darunavir: Two 400 mg tablets taken once daily by mouth (two tablets a day total). Ritonavir: 100mg tablet taken once daily by mouth (one tablet a day total), together with darunavir. Darunavir/ cobicistat: a fixed dose combination containing 800mg of darunavir and 150mg of cobicistat. Etravirine: Two 100 mg tablets taken twice daily by mouth (four tablets a day total). Rilpivirine: One 25mg tablet taken once daily by mouth (one tablet a day total). Study medication will be given from the baseline visit (second pregnancy trimester) until Visit 8 (up to 12 weeks after delivery).