Acetaminophen is frequently used in pregnancy but can be lethal when taken in sufficient quantities. How much of an overdose crosses the placenta and exactly how the in vivo fetus deals with this insult are unknown. However, it does appear that both the mother and fetus can have a good outcome in the third trimester, if treatment is begun early and response is rapid.
Byer AJ, Traylor TR, Semmer JR. Acetaminophen Overdose in the Third Trimester of Pregnancy. JAMA. 1982;247(22):3114-3115. doi:10.1001/jama.1982.03320470060034