Tylenol Warns Against Use During Pregnancy

Effect / Risk
Description / Evidence:

Crossing placenta / fetal exposure
Acetaminophen does cross the placenta, so the fetus is exposed when the mother takes it.

Liver toxicity / hepatotoxicity
One of the most well-known dangers of acetaminophen is overdose, which can cause severe liver damage or failure.
Kidney damage / renal effects
In some cases, particularly with overuse or in vulnerable individuals, there can be negative effects on kidneys.
Overdose / poisoning
Taking more than the safe limit (e.g. > 4 g/day in healthy adults, or cumulative overdoses) increases risk of toxicity.
Anemia
High or excessive use may contribute to low iron levels in some scenarios.