Treasure McGuire, the author of the article, comments:
For a drug to be considered teratogenic, it must demonstrate a dose-related disturbance on embryo or fetus development, producing an irreversible defect present at birth, with a temporal relationship to organ formation.
Shatavari contains steroidal saponins (shatavarins). In ayurvedic medicine, the root is considered a reproductive tonic, with adaptogenic and hormonal activity. Despite long traditional use, data on reproductive use in humans are limited. When Shatavari root was given orally in a therapeutic human equivalent dose (20 g/day) adjusted for body weight (30 mg/100 g/day) to rats, guinea pigs and rabbits, it produced oestrogenic effects on mammary glands and genital organs, and a competitive blockade of oxytocin-induced contractions.2,3 In a randomised study of pregnant rats given Shatavari root 10 mg/100 g/day or a control treatment for 60 days, there was an increased resorption of fetuses, and pups showed teratogenic disorders, gross malformations (e.g. swelling in legs) and intrauterine growth retardation. Live pups showed a significant decrease in body weight and developmental delay. The investigators concluded that the herb be used cautiously in pregnancy, as its exposure during that period may cause damage to the offspring.4
Herbal teas often contain a mix of herbs and doses tend to be much lower than amounts used therapeutically. However, until there is clearer evidence of doses that are safe in pregnant women, it seems prudent to avoid Shatavari in the first trimester (during organogenesis). This does not preclude use in later trimesters or during breastfeeding.