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Burosumab Pregnancy and Breastfeeding Warnings

Burosumab is also known as: Crysvita

Medically reviewed by Last updated on April 24, 2020.

Burosumab Pregnancy Warnings

Benefit should outweigh risk

US FDA pregnancy category: Not assigned

Risk Summary: There is no available human data to inform a drug-associated risk of developmental outcomes; adverse effects were observed in animal studies at an exposure estimated to be 64-fold higher than human exposure.

-Serum phosphate levels should be monitored throughout pregnancy.
-Some authorities advise against use in women of childbearing potential not using contraception.
-Pregnancies should be reported to the manufacturer's (Kyowa Kirin, Inc) adverse event reporting line (US; 1-888-756-8657).

Studies in cynomolgus monkeys without X-linked hypophosphatemia (XLH) found no evidence of teratogenic effects in fetuses or offspring when dosed at 1, 7, and 64-fold the expected human exposure. Maternal hyperphosphatemia and placental mineralization were observed along with increased late fetal loss, a shortened gestation period, and an increased incidence of preterm births at doses 64-fold the expected human exposure. This drug has been detected in the serum of fetuses and offspring of dams exposed to 64-fold human dose. There are no controlled data in human pregnancy.

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.

See references

Burosumab Breastfeeding Warnings

There is no information on the effects of this drug on milk production or on the breastfed infant. This drug is a large protein molecule and therefore the amount excreted into human milk is likely to be very low and absorption unlikely because it will probably be destroyed in the infants gastrointestinal tract. Due to lack of clinical data, the developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for this drug and any potential adverse effects on the breastfed infant from the drug or from the underlying maternal condition.

Safety has not been established

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

-The effects in the nursing infant are unknown.

See references

References for pregnancy information

  1. "Product Information. Crysvita (burosumab)." Ultragenyx Pharmaceutical, Novato, CA.

References for breastfeeding information

  1. "Product Information. Crysvita (burosumab)." Ultragenyx Pharmaceutical, Novato, CA.
  2. National Library of Medicine (US) "Drugs and Lactation Database (LactMed) Available from: URL:" (2006):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.