Animal studies have failed to reveal evidence of embryofetal toxicity or teratogenicity; placental transfer of this drug and/or its metabolites was observed in rats. Placental transfer to the fetus has been reported as low to moderate (cord blood/maternal delivery plasma drug ratio up to 0.6). There are no controlled data in human pregnancy; however, based on human experience, this drug can cause congenital malformations when used during pregnancy.

To monitor maternal-fetal outcomes of pregnant women exposed to antiretroviral therapy, an Antiretroviral Pregnancy Registry (APR) has been established. Healthcare providers are encouraged to prospectively register patients. For additional information: apregistry.com

In the APR, an increased rate of congenital malformations with this drug compared to the general population was observed; the frequency of congenital malformations was higher in infants exposed during the first trimester than in unexposed infants. The prevalence of birth defects with first trimester and second/third trimester exposures was 4.7% and 4.3%, respectively, compared with the background rate of 2.7% in the reference population. After detailed review, no pattern of defects was detected; clinical significance is uncertain.

Fatal lactic acidosis has been reported in pregnant women who received this drug plus stavudine with other antiretroviral agents; coadministration of this drug with stavudine is contraindicated. Healthcare providers should be alert for early diagnosis of lactic acidosis/hepatic steatosis syndrome in HIV-infected pregnant women using this drug.

AU TGA pregnancy category B2: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.

US FDA pregnancy category B: Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women.

This drug should be used during pregnancy only if clearly needed and the benefit outweighs the risk.

AU TGA pregnancy category: B2
US FDA pregnancy category: B

Comments:
-A pregnancy exposure registry is available.
-According to some experts: Women using this drug during pregnancy should be switched to preferred (or alternative) nucleoside reverse transcriptase inhibitor regimens; in addition, this drug is not recommended for initial antiretroviral therapy in pregnancy due to toxicity.

See references

Breastfeeding is not recommended during use of this drug; if replacement feeding is not an option, a different drug may be preferred.

Excreted into human milk: Unknown
Excreted into animal milk: Yes

Comments:
-The effects in the nursing infant are unknown.
-The US CDC, American Academy of Pediatrics, and manufacturer advise HIV-infected women not to breastfeed to avoid postnatal transmission of HIV to a child who may not yet be infected.
-Local guidelines should be consulted if replacement feeding is not an option.

See references