What drug could have been administered during gestation that resulted in a baby being born with shortened limbs?

Thalidomide is a drug known for its teratogenic effects when taken during pregnancy, particularly during the first trimester. The medication was originally prescribed as a sedative and to treat morning sickness, but it was later discovered to cause severe birth defects, notably phocomelia, which is characterized by shortened limbs. The timing of exposure to thalidomide is critical; if taken during the crucial early weeks of organ development, it severely impacts limb formation.

In contrast, the other options listed have different primary effects or different types of birth defects associated with their use. Warfarin is associated with a range of birth defects, including fetal hemorrhage and specific malformations, but not specifically with shortened limbs. Valproic acid can cause neural tube defects and cognitive impairment but is not linked to limb shortening. Isotretinoin is associated with a variety of significant birth defects, particularly facial and cranial malformations, rather than limb abnormalities. Understanding the specific effects of thalidomide underlines its tragic history in maternity pharmacology, making it the correct choice in this context.