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Congenital HIV
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Congenital HIV infection is very uncommon in Australia, largely due to the low prevalence of HIV in pregnant women.
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HIV infection during pregnancy can safely be treated with zidovudine & other anti-retrovirals.
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Effect of maternal HIV infection on pregnancy
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Chemoprophylaxis combined with other interventions such as elective caesarean section and avoidance of breastfeeding can reduce rates of transmission to less than 2%.
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Without interventions the rate of mother to child transmission is approximately 25 - 30%. Factors associated with increased risk of transmission have included high maternal viral load, low CD4 count, prolonged ruptured membranes, vaginal delivery, premature delivery and breastfeeding.
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Pediatric AIDS Clinical Trial Group Protocol 076 Study Group proved chemoprophylaxis (zidovudine) administered to HIV infected women & their newborn, reduces the risk of perinatal transmission by approximately two-thirds (from 25.5% to 8.3%).
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All HIV positive antenatal patients should be referred to Infectious Diseases consultant for continuation of maternal anti-retroviral treatment during pregnancy.
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Ante-Partum
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Zidovudine
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If not receiving zidovudine already, start as soon as HIV status is confirmed positive and continue throughout pregnancy. If already receiving zidovudine, continue throughout pregnancy. Consult infectious diseases specialist for further detail.
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Pregnancy / breastfeeding safety
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- 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.
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- Breastfeeding is NOT recommended in women with HIV due to the risk of viral transmission through breastmilk. Formula feeds are preferred.
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Other anti-retrovirals
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The prescribing of anti-retrovirals to pregnant women is complex, refer to a Infectious Diseases consultant.
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At delivery: Mother-infant rapid intervention
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Zidovudine is the anti-retroviral agent of choice for use during delivery to decrease perinatal transmission.
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For other anti-retroviral agents that may also be used during delivery to decrease perinatal transmission, consult an Infectious Diseases consultant for further advice.
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Zidovudine
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Brand name: Retrovir®
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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.
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Injection: each 20mL vial contains 200mg zidovudine (available via Special Access Scheme (SAS) as it is not registered in Australia).
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Please contact pharmacy for SAS Category A form and Patient Consent form when expected date of caesarean is known. These forms need to be completed and returned to pharmacy so that pharmacy can organise supplies prior to patient admission.
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Syrup for infant: each 5mL contains 50mg zidovudine
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Intra-partum (prevention of maternal-fetal transmission)
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A loading dose is usually required followed by a continuous infusion starting 4 hours prior to a planned caesarean.
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Once the umbilical cord is clamped, intravenous treatment can be ceased.
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Maternal dose: Starting 4 hours prior to planned caesarean (see IV dose calculation below).
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Loading dose: administer zidovudine at 2 mg/kg over one hour and continue.
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Maintenance: at 1 mg/kg/hour until the umbilical cord is clamped.
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IV infusion (Maternal):
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- first withdraw 40mL of sodium chloride 0.9% from the 100mL normal saline bag
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- add 400mg (40mL zidovudine solution) to this 100mL sodium chloride 0.9% bag
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 | - this solution gives a total dose = 400mg in 100mL (ie 4milligram/mL)
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Maternal dose calculation guide:
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| Loading dose rate of infusion
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| mL/hr = (wt in kg x 2mg) / 4
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| Maintenance rate of infusion
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| mL/hr = (wt in kg x 1mg) / 4
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Incompatibilities: check with pharmacy if intending to co-administer with another drug via a Y site.
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Zidovudine infusion bags are stable for 8 hours after reconstitution.
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Management of the infant
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Consult with Infectious Diseases consultant for management of the infant.
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Infant dose:
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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
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or
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(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.)
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Ensure that the entire bottle of Retrovir® syrup is sent home with the infant (it is sufficient to complete the six weeks of therapy).
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If infant unable to tolerate oral feeds, start zidovudine infusion:
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Infant IV infusion:
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1.5mg/kg/dose over 30 minutes every 6 hours
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NB: For dilution and administration details contact pharmacy.
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Zidovudine side effects and contraindications
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Side effects:
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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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Other side effects are nausea, vomiting, headache, fever and myalgia. Depending on severity, it may require a reduction in dose or change in the therapy.
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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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Comments:
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- 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.
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Links
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The American Center for Disease Control and Prevention
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Maternal-Child Transmission: Aids Info (The living document).
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Royal Women's Hospital Clinical Practice Guidelines (CPGs) are intended to provide guidance to health care professionals, based on a thorough evaluation of research evidence, on the practical assessment and management of specific clinical issues or situations. The guidelines allow some flexibility on the part of the health care professional based on the needs of the specific patient for whom they are caring.
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