Acetaminophen use in pregnant patients

You are correct in stating that acetaminophen has been deemed safe for pregnant patients. It is known to cross the placental barrier however research has shown that there is no increased risk of major congenital malformations, miscarriage, or still birth. Some studies reported a possible association between Acetaminophen use during pregnancy and risks of fetal neurodevelopmental, reproductive, and urogenital disorders. However, more recent studies with lower bias risks have not supported this association. The Society of Obstetricians and Gynaecologists of Canada (SOGC), along with several international societies, view the evidence for this causation as weak and flawed.

Available data states that there is no increased risk associated with short-term use of acetaminophen at recommended doses. Furthermore, acetaminophen is the recommended first-line treatment option for pain management in pregnancy when medically indicated. Dose adjustments for pregnant patients are not recommended and the doses of acetaminophen in the Advanced Life Support-Patient Care Standards (ALS PCS) are appropriate for pregnant patients.

Regarding dosing, 4000mg would be the daily cumulative max dose amount for an adult. However, due to risk for hepatotoxicity, some experts recommend a lower maximum dose of 3g per day.