Animal studies have shown visceral and skeletal malformations in rabbits in doses ranging from 10 to 20 times the human dose and a decrease in the number of live pups delivered by rats receiving up to 2 and 5 times the maximum recommended human dose of carbidopa and levodopa respectively, during organogenesis. Levodopa appears to cross the human placental barrier, enter the fetus and be metabolized; carbidopa concentrations in fetal tissue appear to be minimal. There are no adequate or well controlled studies in pregnant women.

AU TGA pregnancy category B3: 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 have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

This drug should not be used during pregnancy unless the benefit outweighs the risk to the fetus.

AU TGA pregnancy category: B3
US FDA pregnancy category: C

Comments: Women of childbearing potential should discuss use of contraception with their health care provider.

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

Excreted into human milk: Yes (levodopa)
Excreted into animal milk: Yes (carbidopa)

Comments: This drug in relatively low doses was used without apparent harmful effects in the nursing infant by 1 mother with Parkinson's disease; limited data indicate this drug is poorly excreted into breast milk.

Limited data suggest levodopa is poorly excreted into breast milk; the sustained-release product appears to transfer in smaller amounts than the immediate-release product. In a single mother with Parkinson's disease receiving sustained-release carbidopa 50 mg-levodopa 200 mg 4 times daily, peak breast milk levodopa concentrations measured at 4.5 months postpartum were 315 mg/L. Following a single dose of immediate-release carbidopa 50 mg-levodopa 200 mg, a peak concentration of 683 mcg/L was obtained. This data suggests an infant would receive 0.3% or 0.5% of the maternal weight-adjusted dose with the sustained release or the immediate-release product, respectively. Levodopa decreases serum prolactin; the prolactin level in a mother with established lactation may not affect her ability to breastfeed.

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