also detects a protein called p24 in maternal blood, which is a specific component of the hiv virus itself and also acts as an early marker of an hiv infection. if this test is positive, the cdc recommends performing follow-up testing using a test called the hiv-1/hiv-2 antibody differentiation immunoassay that both confirms the diagnosis and determines the specific type of hiv infection the patient has to specifically tailor further management of the patient. sometimes, however, a person may be infected with hiv but the body has not produced enough antibodies to be detected by the test. if a woman has risk factors for hiv infection or symptoms of an acute infection but tests negative on the initial screening test, she should be retested in 3 months to confirm that she does not have hiv, or she should receive further testing with an hiv rna assay, which can be positive earlier than the antibody/antigen immunoassay. antiretroviral medications should be initiated at the time of maternal hiv diagnosis and they should be continued indefinitely. treatment/management prevention of mother-to-child transmission the risk of hiv transmission from mother to child is most directly related to the plasma viral load of the mother. untreated mothers with a high (hiv rna greater than 100,000 copies/ml) have a transmission risk of over 50%. for women with a lower viral load (hiv rna less than 1000 copies/ml), the risk of transmission is less than 1%. in general, the lower the viral load, the lower the risk of transmission. for this reason, art is recommended throughout the pregnancy so that viral load levels remain as low as possible and the risk of transmission is reduced. the usage of art drugs that effectively cross the placenta can also act as pre-exposure prophylaxis for the infant, as they can achieve adequate art drug levels in the fetus to prevent acquisition of the viral illness. finally, it is recommended that art drugs be administered to the infant following birth to continue to provide protection from the virus that the infant could have been exposed to during labor and delivery. modern-day antiretroviral therapy all pregnant women who test positive for hiv should begin and continue art therapy regardless of cd4 counts or viral load to reduce the risk of viral transmission. the earlier art is initiated, the more likely the viral load will be suppressed by the time of delivery. some women are concerned about using art early in the pregnancy, as babies are most susceptible to drug toxicities during the first trimester. however, delaying art initiation may be less effective in reducing infection transmission. antiretroviral therapy is most importantly used at the following times in pregnancy to reduce the risk of mother-to-child transmission of hiv: during pregnancy: pregnant women infected with hiv receive an oral regimen of at least three different anti-hiv medications. during labor and delivery: pregnant women infected with hiv who are already on triple art should continue with their oral regimen. if their viral load is high (hiv rna greater than 1,000 copies/ml), or there is question about whether medications have been taken consistently, then intravenous zidovudine (azt) is added at the time of delivery. pregnant women who have not been on art prior to delivery or who have been on art for less than four weeks should also be given intravenous azt or a single dose of nevirapin (sdnvp), tenofovir (tdf) and emtricitabine (ftc) and a three-hourly dose of azt. according to current recommendations by the who, cdc and u.s. department of health and human services (dhhs), all individuals with hiv should begin art as soon as they are diagnosed with hiv. the recommendation is stronger in the following situations: cd4 count below 350 cells/mm3 high viral load (hiv rna greater than 100,000 copies/ml) progression of hiv to aids development of hiv-related infections and illnesses pregnancy labor and delivery women should continue taking their art regimen on schedule and as prescribed throughout both the prenatal period and childbirth. the viral load helps determine which mode of delivery is safest for both the mother and the baby. according to the nih, when the mother has been receiving art and her viral load is low (hiv rna less than 1000 copies/ml) at the time of delivery, the risk of viral transmission during childbirth is very low and a vaginal delivery may be performed. a cesarean delivery or induction of labor should only be performed in this patient population if they are medically necessary for non-hiv-related reasons. if the maternal viral load is high (hiv rna greater than 1000 copies/ml) or if her hiv viral load is unknown around the time of delivery (more than 34 weeks gestation), it is appropriate to schedule a cesarean delivery at 38 weeks to reduce the risk of hiv transmission during childbirth. in these situations, this is the appropriate management guideline regardless of whether or not the mother has taken prenatal art. sometimes, women who have a high viral load who should receive a caesarean delivery will present to the hospital when their water breaks or they are in labor, and management for these patients is specific to each patient and will be determined at the time of presentation, as a cesarean delivery may not significantly reduce the risk of infection transmission. the nih recommends that healthcare providers in the united states contact the national perinatal hiv/aids clinical consultation center at 1-888-448-8765 for further recommendations in these situations. all women who present to the hospital in labor and their hiv status is unknown or they are at high risk of contracting an hiv infection but have not received repeat third trimester testing should be tested for hiv using a rapid hiv antigen/antibody test. if the rapid screening is positive, intravenous (iv) zidovudine should be initiated in the mother immediately and further confirmatory testing should be performed. iv zidovudine is an antiretroviral drug that should be administered to women at or near the time of delivery in the following situations: high viral load (hiv rna greater than 1000 copies/ml) unknown viral load clinical suspicion for maternal noncompliance with prenatal art regimen positive rapid hiv antigen/antibody test at labor or prior to a scheduled caesarean delivery administration of iv zidovudine can be considered on a case-by-case basis for women who have a moderate viral load (hiv rna greater than or equal to 50 copies/ml and less than 1000 copies/ml) near the time of delivery. iv zidovudine is only not administered if women are both compliant with their prescribed art regimen throughout pregnancy and have maintained a low viral load near the time of delivery (hiv rna less than 50 copies/ml between 34 and 36 weeks gestation). further considerations for managing hiv positive women during labor and delivery include the following recommendations to reduce the risk of hiv transmission: avoid fetal scalp electrodes for fetal monitoring, particularly if the maternal viral load is greater than 50 copies/ml. avoid artificial rupture of membranes and operative vaginal delivery (using forceps or a vacuum extractor) if at all possible, particularly in women who have not achieved viral suppression. if these methods need to be employed, they should be conducted carefully and following obstetric standards. the potential interactions between the specific art drugs taken by the mother and those administered during labor should be considered by healthcare providers prior to drug administration. immunizations all pregnant women should receive the inactivated influenza vaccine and the tdap vaccine, which covers tetanus, diphtheria, and pertussis (whooping cough) during the first trimester, regardless of their hiv status. if a pregnant woman tests positive for hiv, she should also be administered the pneumococcal vaccine, meningococcal vaccine, and hepatitis a vaccine and hepatitis b vaccine following a conversation with her provider. vaccination is important to prevent serious infectious complications associated with the aforementioned diseases, which patients with hiv are at higher risk of contracting. pregnant women should notably not receive live vaccines, including the human papilloma virus (hpv) vaccine, measles mumps and rubella (mmr) vaccine, live influenza vaccine, and varicella (chicken pox) vaccine regardless of their hiv statuses, as these vaccines can potentially harm the fetus. further evaluation the following monitoring tests are recommended for women who are diagnosed with hiv prior to or during pregnancy: hiv viral load (via hiv rna levels) at the initial prenatal visit, 2–4 weeks after starting or changing art, monthly until viral load is undetectable, at least every 3 months subsequently throughout pregnancy, and between 34 and 36 weeks to inform decisions regarding labor and delivery. cd4 count at the initial prenatal visit. this lab should be repeated every 3 months for pregnant women have been on art for less than 2 years, have inconsistent art compliance, cd4 counts less than 300 cells per millimeter cubed, or a high viral load. otherwise, cd4 count does not need to be monitored following the initial visit. hiv drug resistance testing should be performed prior to initiating art in any pregnant woman including those who have and have not taken antiretroviral medications before, and when modifying failing art regimens for pregnant women. note, art should be initiated prior to receiving the results of drug resistance testing. standard glucose screening to monitor for gestational diabetes. liver function tests within 2–4 weeks after initiating or changing art drugs and every 3 months subsequently. monitoring for art toxicities based on the specific drugs that have been prescribed. aneuploidy screening should initially be offered via noninvasive methods. if these tests are abnormal or an abnormal ultrasound is performed, invasive testing via amniocentesis or chorionic villus sampling can be performed once an art has been initiated and the hiv viral load is undetectable. hepatitis a, b, and c screening should be performed in all pregnant women with hiv because coinfection is common. further sexually transmitted infection (sti) screening should be performed as hiv positive women are at a higher risk for co-infection than the general population, and exposure to other stis is associated with stillbirth, preterm delivery, low birth weight, and other complications. screening should include syphilis, gonococcal, chlamydial, and trichomonal infection. tuberculosis testing as hiv positive patients are at high risk for developing active tuberculosis. testing for prior toxoplasma exposure should be performed in hiv infected pregnant women, as reactivation of toxoplasma gondii infection can occur with a low cd4 count (less than 100 cells per microliter), and has the potential to cause congenital toxoplasmosis in the fetus, which has many associated birth complications. testing for cytomegalovirus (cmv) exposure should similarly be performed, as cmv is the most common congenital infection and is associated with congenital hearing loss, major handicaps, and death in exposed infants. antiretroviral medications the goals of antiretroviral administration during pregnancy are to reduce the risk of transmission of hiv from mother to child, to slow maternal disease progression, and to reduce the risks of maternal opportunistic infection and death. it is important to choose medications that are as safe as possible for the mother and the fetus, and are effective at decreasing the total viral load. certain antiretroviral drugs carry a risk of toxicity for the fetus. however, the overall benefits of an effective art regimen outweigh the risks and all women are encouraged to use art for the duration of their pregnancy. it is important to note that the associations between birth defects and antiretroviral drugs are confounded by several important factors that could also contribute to these complications, for example: exposure to folate antagonists, nutritional and folate status, and tobacco, alcohol, and drug use during pregnancy. the recommended art regimen for hiv-positive pregnant women is similar to that of the general population. in the united states, the favored art regimen is a three-drug routine in which the first two drugs are nrtis and the third is either a protease inhibitor, an integrase inhibitor, or an nnrti. nucleoside reverse transcriptase inhibitors (nrtis) are considered the "backbone" of art and 2 of these medications are generally used in combination. due to its known safety profile and extensive use in pregnant patients, zidovudine-lamivudine is the preferred choice as the nrti backbone. zidovudine may worsen anemia so anemic patients are advised to use an alternative agent. for women who are coinfected with hepatitis b, tenofovir with either emtricitabine or lamivudine is the preferred nrti backbone. nrti use may cause a life-threatening complication called lactic