Animal studies have not been conducted. There are no controlled data in human pregnancy. A Brazilian case control study found no significant difference in the odds ratio of spontaneous abortion among vaccinated women compared to a similar unvaccinated group. In a study in Trinidad of immunization of 100 to 200 pregnant women, no pregnancy related adverse events were reported; of 41 cord blood samples from infants of mothers immunized in the first trimester, one tested positive for IgM antibodies in an infant that appeared normal at delivery with no subsequent adverse sequelae reported. The positive IgM result suggests transplacental infection with 17D viruses can occur. In a study of 101 Nigerian women, 88% of whom were in the third trimester, none of the 40 infants born in a hospital tested positive for IgM antibodies, however the percentage of women who seroconverted was reduced compared to a non-pregnant control group (38.6% versus 81.5%)

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 Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

Use is not recommended unless clearly needed.

AU TGA pregnancy category: B2
US FDA pregnancy category: Not assigned

See references

A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.

Use is contraindicated in lactating women providing breastmilk to infants under 9 months of age.

Excreted into human milk: Data not available
Excreted into animal milk: Data not available

Comments:
-As of July 2015, three reports of vaccine-associated neurotropic disease in exclusively breastfed infants have been reported worldwide with yellow fever vaccine; all were under 1 month of age at the time of exposure.
-Age less than 9 months is a risk factor for yellow fever vaccine-associated neurotropic disease.
-Discuss the risks and benefits of vaccination in women providing breastmilk to infants 9 months and older.

See references