The safety of valerian during pregnancy and breastfeeding has not yet been established through clinical (human) studies.[1]
While in vitro studies have noted that valerenic acid doesn’t cross the placenta, it’s important to consider that valerian comprises multiple constituents, some of which may not have been tested.[2]
Finally, one study on rats observed that high doses of postpartum valerian supplementation altered maternal milk composition.[3] These results should be further investigated by clinical studies.