HIV perinatal
Dot point summary
Congenital HIV infection is very uncommon in Australia, largely due to the low prevalence of HIV in pregnant women
Chemoprophylaxis combined with other interventions such as elective caesarean section and avoidance of breastfeeding can reduce rates of transmission to less than 2%
HIV infection during pregnancy can safely be treated with zidovudine & other anti-retrovirals
Mother to baby transmission
HIV (Human Immunodeficiency Virus) may be transmitted from mother to baby at any time during the pregnancy, during labour, or as a result of breastfeeding. This type of transmission is called perinatal HIV transmission or vertical transmission or mother-to-child transmission of HIV. Without interventions the rate of mother to baby transmission is approximately 25-30%. Factors associated with increased risk of perinatal transmission include
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acute stage of the mother's illness
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high maternal viral load
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low CD4 (T cell) count
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prolonged rupture of the membranes
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vaginal delivery
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premature delivery
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breastfeeding
The rate of perinatal HIV transmission can be as low as 1-2% if the following strategies are used
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perinatal prophylactic antiretroviral therapy (to mother and newborn)
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elective Caesarean section
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formula feeding (one of the few indications in Australia)
Other strategies that are thought to be beneficial include the avoidance of
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artificial rupture of the membranes
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use of fetal scalp electrodes
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fetal blood sampling
All HIV positive antenatal patients should be referred to an Infectious Diseases consultant for continuation of maternal anti-retroviral treatment during pregnancy. Women who are HIV positive and pregnant require an integrated multidisciplinary approach to care. Experienced HIV physicians, obstetricians, midwives and social workers should work closely during the pregnancy, preferably as early as possible. This is important to
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establish an early rapport with the parents
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offer counselling on the current strategies to minimise the risk of perinatal HIV transmission
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prepare them for when the baby is born
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offer postnatal antiretroviral prophylaxis
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offer pneumocystis carinii pneumonia prophylaxis
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complete the testing process involved in establishing a diagnosis in the baby
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provide education to staff involved in the management of the woman
The privacy of the woman and family must be respected and care and attention to her needs should also be observed. Health care providers must not assume that partners, parents, relatives, friends or even other health care workers are informed of the woman's HIV status. Neither can they assume that the woman is prepared for any or all of these contacts to know. Health care professionals need to be guided by the woman's wishes in this regard.
Antenatal maternal management
Data from the AIDS Clinical Trials Group study demonstrated a significant decrease in perinatal HIV transmission (~ 70% reduction from 25% to 8%) when pregnant women and their babies received a 3 part AZT (zidovudine) regimen
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AZT during pregnancy (after the 14th week of gestation)
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intrapartum intravenous AZT
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6 weeks of AZT to babies
If the mother is not already receiving treatment, this should be started as soon as HIV status is confirmed positive. Ideally treatment should commence during the second trimester and no later than the beginning of the third trimester and continue throughout pregnancy. Prescribing of anti-retrovirals to pregnant women is complex and should be referred to an Infectious Diseases consultant.
Perinatal Management
AZT (Zidovudine - Retrovir®) is the anti-retroviral agent of choice for use during delivery to decrease perinatal transmission. For other anti-retroviral agents that may also be used during delivery to decrease perinatal transmission, consult an Infectious Diseases consultant for further advice.
Zidovudine is an anti-retroviral agent. It is used for the treatment of HIV infection and provides protection for the baby during delivery, and decreases perinatal transmission when taken by the baby for 6 weeks after birth. Each 20mL vial (for injection) contains 200mg zidovudine (available via Special Access Scheme (SAS) as it is not registered in Australia).
Elective Caesarean Section
A loading dose is usually required followed by a continuous infusion starting 4 hours prior to a planned caesarean. Once the umbilical cord is clamped, intravenous treatment can be ceased.
Maternal dose:
Starting 4 hours prior to planned caesarean (see IV dose calculation below)
Loading dose: administer zidovudine at 2 mg/kg over one hour and continue Maintenance: at 1 mg/kg/hour until the umbilical cord is clamped
IV infusion (Maternal)
With Onset of Labour
This is applicable in the following scenarios
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the mode of delivery opted for after counselling is via normal vaginal delivery
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spontaneous labour occurs before the date of elective Caesarean section. AZT should commence in the time interval during the preparation for a semi-urgent Caesarean section (however, the Caesarean section should not be delayed to complete the intravenous course of AZT)
Loading dose: administer zidovudine at 2 mg/kg over one hour and continue Maintenance: at 1 mg/kg/hour until the umbilical cord is clamped
Maternal Weight
(Kg)
Loading dose rate of infusion
(to be run over 60mins)
mL/hr = (wt in kg x 2mg) / 4
Maintenance rate of infusion
( to run after loading dose and
until the umbilical cord is clamped)
mL/hr = (wt in kg x 1mg) / 450
25
12.5
55
27.5
13.75
60
30
15
65
32.5
16.25
70
35
17.5
75
37.5
18.75
80
40
20
85
42.5
21.25
90
45
22.5
Incompatibilities: check with pharmacy if intending to co-administer with another drug via a Y site. AZT (Zidovudine) infusion bags are stable for 8 hours after reconstitution.
Pregnancy/breastfeeding safety
AZT (Zidovudine) is rated as Category B3 during pregnancy by the Australian Drug Evaluation Committee, Therapeutic Goods Administration (ADEC TGA). There is now good data on zidovudine use in pregnancy. The potential benefits to the mother and fetus far outweigh potential risks to the fetus.
Breastfeeding is NOT recommended in women with HIV due to the risk of viral transmission through breast milk. Formula feeds are preferred. However, skin-to-skin contact between mother and baby should still be encouraged.
Other perinatal management issues
There are no known contra indications to the use of short-term steroids to promote fetal lung maturity in women with HIV.
There are no known contraindications to an HIV positive woman having either a general or epidural anaesthetic.
Obstetric/Perinatal aspects of management which may reduce vertical transmission
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avoid early artificial rupture of membranes (ARM)
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if artificial rupture of membrane (ARM) is undertaken, careful use of the amnihook is necessary so that scalp integrity is maintained
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assess fetal well being using non-invasive methods - avoid the use of fetal scalp electrodes and fetal blood sampling. An open wound may allow direct entry of HIV from mother to infant
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the use of forceps or Ventouse extraction may cause a loss of skin integrity increasing the risk of transmission, however this does not preclude their use as required
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on delivery of the head, gently wipe the baby's eyes free of secretions
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suction is not generally required, but if it is, be gentle to avoid damage to mucous membranes
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clamp the cord as soon as possible, milking between the clamps in a direction away from the baby
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place a sponge over the cord before cutting to prevent spurting of blood
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once born, towel dry the baby. Cleanse the baby as soon as possible
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prior to any procedures on the neonate that will disrupt skin or mucous membrane integrity, ensure the area is thoroughly cleaned. An example is the administration of IMI Vitamin K
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ensure that standard precautions are utilised when handling/cleaning up blood/body fluid spillage
Neonatal Management
Neonatal management should always be in consultation with an Infectious Disease Consultant
Diagnosis of HIV in neonates
Whilst the diagnosis of HIV infection in adults is readily established by the detection of HIV antibodies, the situation is more complex in babies born to HIV positive women. During the pregnancy, the fetus passively acquires maternal HIV antibodies across the placenta. This does not mean the fetus is infected but rather has "acquired" the antibodies from the mother.
The babies will always test "HIV antibody positive" as the test will detect antibodies derived from the mother. Therefore, the HIV antibody test alone cannot be relied on in these babies, since all babies born to HIV positive women will test positive to HIV antibodies (and in the vast majority of cases are unlikely to be infected). It can take up to 12 -18 months for a baby to clear these maternal antibodies.
For this reason, a sensitive nucleic acid based technique called the "PCR" (polymerase chain reaction) is used to detect the presence of HIV in babies. Multiple negative tests to age 6 months are required to confirm an "uninfected" status in exposed infants. In uninfected babies, it is recommended that the child have a "final" test at 18 months (the HIV antibody test) to show that the baby has cleared all the passively acquired HIV antibodies. If a PCR is positive, the test is always repeated as soon as possible (on a new sample) before it is confirmed that the baby is infected. All babies born to HIV positive women should be followed into adulthood by a Paediatrician.
Suggested testing regimen for infants at risk
All babies who have been perinatally exposed to HIV should have close follow up. Blood tests will be done at
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week 1 - (prior to discharge from hospital)
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week 6
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week 12
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6 months
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12 months - clinical review (testing optional)
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18 months - final clinical review (if HIV antibodies have cleared)
Infant AZT dosages
After clamping of umbilical cord or within 6 to 8 hours of delivery, start oral zidovudine and continue for 6 weeks
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2mg/kg/dose every 6 hours or
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4mg/kg/dose twice a day
If infant vomits more than 15 minutes after dose, give next dose at next scheduled time. If infant vomits within 15 minutes of a dose, give another dose if possible. Ensure that the entire bottle of Retrovir® syrup is sent home with the infant (it is sufficient to complete the six weeks of therapy). Each 5mL of zidovudine syrup contains 50mg zidovudine.
If infant unable to tolerate oral feeds, start zidovudine infusion.
Infant IV infusion - 1.5mg/kg/dose over 30 minutes every 6 hours, dilute to 4mg/ml, compatible with 5%Dextrose or N Saline
Zidovudine side effects
Parenteral zidovudine is generally well tolerated at the doses recommended for this indication.
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blood counts should be monitored for anaemia, neutropenia and leucopenia
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anaemia in the infant generally resolves within 6 weeks after completion of zidovudine therapy. Follow-up blood work should be performed at 2 and 4 weeks after birth to check for these side effects
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liver functions tests for elevated bilirubin and transaminase levels
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other side effects include
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nausea
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vomiting
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headache
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fever
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myalgia
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Depending on severity, it may require a reduction in dose or change in the therapy.
Zidovudine Contraindications
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avoid in patients exhibiting abnormally low neutrophil counts (less than 0.75 x 109/L) or
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abnormally low haemoglobin levels (less than 75g/L)
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contact Infectious Diseases consultant when newborn infants
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have hyperbilirubinaemia requiring treatment other than phototherapy or
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have increased transaminase levels (above 5 times the upper limit of normal)
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Other treatment
The mother and the baby may require other anti-retroviral agents (given orally). An infectious diseases physician or clinical microbiologist would make this decision on an individual case basis.
Pneumocystis (PCP) prophylaxis
PCP prophylaxis is recommended for all babies born to HIV infected women. It is commenced at 6 weeks and continues until testing at 3 months confirms the absence of HIV infection in formula fed infants. This is discussed with the parents to assist them in making informed decision. Treatment is with Co-Trimoxazole. There are several regimens. One suggested regimen is 0.5 ml/kg/day for 6 weeks (dose based on the trimethroprim component).
Immunisations
Routine childhood immunisations (DTPa -hep B, Hib, poliovirus vaccine, MMR, meningococcal and pneumococcal disease) should be given to all babies according to the schedule. Inactivated injectable polio vaccine given subcutaneously is administered instead of the oral polio vaccine to all babies born to HIV infected mothers to minimise the risk of OPV strains being transmitted to immunocompromised members of the family. MMR is safe for contacts and for all patients except those with severely compromised immune function. It is preferable to give MMR rather than expose a child to the risk of infection with wild type measles. Varicella vaccine is recommended for children aged 12 months or more with normal immune function.
Links
- CDC: HIVAIDS Treatment
- American HIV Treatment Information Service (AIDSinfo)
- AIDSinfo: Treatment Regimens for HIV Positive Pregnant Women
- British HIV Association
References
Connor EM, Sperling RS. Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine (AZT) treatment. N Engl J Med 1994; 331:1173-1180.
The mode of delivery and the risk of vertical transmission of human immunodeficiency virus type 1--a meta-analysis of 15 prospective cohort studies. The International Perinatal HIV Group. N Engl J Med 1999; 340:977-987.
Breastfeeding and the use of human milk: Policy Statement. American Academy of Pediatrics. Pediatrics, February 2005; 115 (2): 496-506.
HIV infection in pregnancy and neonatal diagnosis: A guide to management. Sydney Children's Hospital, Royal Hospital for Women and Albion Street Centre
Updated 28 February 2011
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