Acquired immunodeficiency syndrome (AIDS) was first described in 1981, when several patients developed defective cellular immunity and Pneumocystis jiroveci (formally Pneumocystis carinii) pneumonia.¹ Through attacking the body’s own immune system, HIV places the patient at risk for opportunistic infections. HIV can be transmitted through blood and other bodily fluids, including amniotic fluid and saliva.

The incidence of AIDS in the United States is depicted in Figure 29-1. According to the Centers for Disease Control and Prevention (CDC), 1.2 million people in the United States were living with HIV in 2015.² A total of 19% of infected individuals are women, and 1 in 8 patients do not know that they carry the disease.² Each year, 8500 HIV infected women give birth, so it is important for OB/GYN hospitalists to know how to manage these patients.³

Perinatal transmission, or passage of the virus from mother to infant, can happen anytime during the antepartum, intrapartum, or postpartum period. Risk of vertical transmission is related to the maternal viral load (VL) at the time of exposure (Figure 29-2).⁴

All pregnant women, regardless of VL, are encouraged to be on antiretroviral therapy (ART). Through decreasing the VL and providing preexposure prophylaxis to the fetus, this treatment can dramatically decrease the risk of transmission.⁵ The six classes of ART are listed in Table 29-1. The OB/GYN hospitalist must be familiar with the nucleoside reverse transcriptase inhibitors, zidovudine/lamivudine, also known as azidothymidine (AZT), which is the mainstay medication given perinatally to decrease transmission. With minimal toxicity and ability to cross the placenta, AZT is the first-line medication for preventing exposure to the neonate.⁶

With the implementation of universal HIV testing, ART, and conscious efforts to minimize exposure to the virus, the rates of perinatal transmission have decreased by 90% over the past two decades. Following appropriate protocols, the risk of transmission is now around 1% (Figure 29-3).³

The goal of the OB/GYN hospitalist in treating pregnant women infected with HIV is to decrease vertical transmission. Appropriate interventions for pregnancy include universal screening for HIV in pregnancy, prenatal combined ART, selected delivery method based on VL, appropriate medications during labor and delivery (L&D), avoidance of breastfeeding in the postnatal period, and neonatal prophylaxis. The combination of these interventions decreases transmission to 1%.

THE PREVIOUSLY UNSCREENED PATIENT

All patients presenting for delivery who have not previously been screened for HIV should have rapid HIV screening performed. This rapid screen checks for antibodies and the results should take approximately 20 minutes to return. It has >98% sensitivity and specificity.⁵ If this test is positive, confirmatory testing should be sent, and the patient should be presumed HIV positive until confirmatory testing returns days later. This treatment includes intravenous (IV) AZT, cesarean section (C-section) for delivery, and avoidance of breastfeeding. Along with confirmatory testing, an HIV workup should be done, including CD4 counts, VL, and genotype testing.

All pregnant women should be screened in early pregnancy for HIV (opt-out screening), and those with risk factors should be rescreened at 36 weeks gestation. Risk factors that may increase the incidence of infection are presented in Table 29-2.⁷ For those deemed at risk who have not been rescreened in the third trimester, rapid screening upon admission for delivery should be performed.

WOMEN WHO HAVE RECEIVED ANTIRETROVIRAL THERAPY DURING PREGNANCY WITH VL < 1000 COPIES/ML

For those women who have had appropriate care during pregnancy and who have been on ART, delivery planning is based on the recent VL. In women on ART during pregnancy and with a recent VL < 1000 copies/mL, vaginal delivery is an option. In this select group of virally suppressed patients, C-section has not been shown to provide additional protection from vertical transmission.^8–11 These women should continue their ART medications throughout L&D, taking care not to miss any doses.

Newer data supports the idea that there is no additional benefit of receiving IV AZT in this population. There have been three recent cohort studies that stratified the risk of transmission based on ART treatment, VL, and IV AZT at delivery.^8,9,12 These studies all showed that in women who were on ART and had recent VL < 1000 copies/mL, when IV AZT was not given peripartum, there was no increase in the rate of transmission. Based on this new data, IV AZT does not appear to provide any added benefit for this group of women to prevent perinatal transmission. If there is any concern about compliance with the medication regimen or if there is no recent VL, then IV AZT should still be given. However, regardless of VL, the clinician may elect to use intrapartum IV AZT after discussion with the patient and based on individualized clinical assessment.

WOMEN WITH VL > 1000 COPIES/ML, WOMEN WITH UNKNOWN VIRAL LOADS, AND WOMEN WITH NO CURRENT HIV TREATMENT OR NEW DIAGNOSIS

Women with an unknown VL or VL > 1000 copies/mL should deliver by C-section, and this is ideally scheduled at 38 weeks gestation, prior to the onset of labor. Antiretroviral medications should be continued throughout the preoperative process except for oral AZT, which need not be given while IV AZT is being given. Medications can be taken with a sip of water. Those that need to be taken with food can be taken with liquid dietary supplements as cleared with anesthesia. Stopping medications should be avoided, as it can increase the risk of drug resistance.¹³ If, for some reason, medications need to be stopped temporarily, they should all be stopped together and all restarted together, again to decrease the risk of drug resistance.⁵ IV AZT should be given at least 3 hours prior to scheduled C-sections and until delivery. This includes a 1-hour loading dose, followed by a continuous IV infusion for 2 hours (3 hours total) before scheduled C-section time. This is based on pharmacokinetic data of AZT in pregnant women during pregnancy and intrapartum.¹⁴

C-sections have been shown to decrease the transmission risk when the VL is >1000 copies/mL in randomized clinical trials and a large meta-analysis.^8–11,15,16 Studies have shown a decreased vertical transmission risk in babies delivered via C-section in the earlier years of HIV perinatal transmission, and prior to the routine use of antiretroviral medications during pregnancy (Table 29-3).

WOMEN WHO ARE RESISTANT TO AZT OR ARE NOT ON AZT AS PART OF THEIR ANTIRETROVIRAL THERAPY REGIMEN

Women who have had resistance testing and are documented to have AZT resistance should still receive IV AZT if it is indicated preoperatively, even if their antepartum drug regimen does not include AZT. They should also continue their routine ART drug regimen intrapartum, in addition to the IV AZT.⁵ Women with resistance to AZT can have mixed populations of the virus, and not all are resistant to AZT.¹⁷ There are many factors of AZT that, regardless of resistance, afford benefits, including a high placenta penetration, conversion to active triphosphate within the placenta, and the benefit to the newborn of receiving AZT immediately prior to delivery (high exposure time) and after delivery (newborn prophylactic AZT).^18–22 The ideal neonatal prophylaxis regimen for infants of women with AZT resistance should be discussed with a pediatric infectious disease specialist, preferably prenatally.

RUPTURE OF MEMBRANES OR LABOR PRIOR TO SCHEDULED CESAREAN SECTION

For patients requiring C-section who present in labor or with ruptured membranes prior to scheduled delivery, especially those who are not virally suppressed, care should be individualized. IV AZT should be started immediately upon presentation, while the plan of care is being formulated. Management should take into account the stage of labor, duration of the rupture of membranes, current ART regimen, and the HIV RNA level if known. Consultation with a HIV specialist and Maternal Fetal Medicine (MFM) specialist is recommended.

PRETERM LABOR AND PRETERM PREMATURE RUPTURE OF MEMBRANES

Preterm labor should be managed as clinically indicated for routine obstetric indications. Corticosteroids for fetal lung maturity are given for routine obstetric indications.