If a woman takes a high risk medication during pregnancy, is it possible for the med to cause some type of mutation of genes resulting in birth defects?

Thalidomide is a nausea med available in Britain & less so in Canada about 60 yrs ago. Women who took it between 5-8 wks of pregnancy often gave birth to babies with deformed or absent arms or legs. Later research led to classification of drugs by the risks they posed during pregnancy. Genes are firmly in place by the time of conception, but drugs effect can alter how those genes work.

High risk medications can cause fetal damage or fetal loss, but not usually via gene mutations. Similarly there are infections which can cause serious damage to an unborn baby, but not usual via gene mutation.