It is a canon of medicine that especial care and caution be taken with medicating expctant mothers. The problem is that this guideline is too often overriden by prescribing drugs that are insufficiently tested or experimental.
Thalidomide was first used as a sedative and later for morning sickness (nausea of pregnancy). It was first approved in Germany in the 1950s and later in other countries and declared by doctors, nurses and pharmacists to be “safe” - even in pregnancy because it was assumed the drug would not reach the foetus. Many countries used the “safe wonder drug” for a limited time until adverse drug reaction reports started to mount and it was realised the drug could produce major limb deformities and even death on a single dose. It was a drug regulatory failure of mammoth proportions which gave rise to modern day drug regulatory quality, safety and efficacy guidelines.
Use of isotretinoin during pregnancy has produced a cluster of birth defects, typically ear dysplasia, brain malformations, and heart defects. Griseofulvin has been linked to conjoined twinning and stillbirth in the USA. Certain anticonvulsant drugs used by epileptic mothers may increase the risk of congenital malformations. A particular concern is that of valporic acid with spina bifida.