Animal studies with ibuprofen have failed to reveal evidence of developmental abnormalities, however, administration of nonsteroidal anti-inflammatory drugs (NSAIDs) during the third trimester of pregnancy may cause significant adverse effects, including premature closure of the fetal ductus arteriosus. Animal studies with famotidine have failed to reveal evidence of impaired fertility or fetal harm. While no direct fetotoxic effects with famotidine have been observed, sporadic abortions occurred in rabbits with marked decreased food intake who received doses of 200 mg/kg/day or higher. There are no controlled data in human pregnancy.

US FDA Drug Safety Communication (10-2020): The FDA is requiring a new warning be added to NSAID labeling describing the risk of fetal kidney problems that may result in low amniotic fluid. The FDA is recommending pregnant women avoid NSAID use at 20 weeks gestation or later. Through 2017, the FDA has received 35 reports of low amniotic fluid levels or kidney problems in mothers who took NSAIDs while pregnant. Five newborns died; 2 had kidney failure and confirmed low amniotic fluid, 3 had kidney failure without confirmed low amniotic fluid. The low amniotic fluid started as early as 20 weeks of pregnancy. There were 11 reports of low amniotic fluid levels during pregnancy and the fluid volume returned to normal after the NSAID was stopped. The medical literature has reported low amniotic fluid levels with use of NSAIDs for varying amounts of time, ranging from 48 hours to multiple weeks. Complications of prolonged oligohydramnios may include limb contractures and delayed lung maturation. In some postmarketing cases of impaired neonatal renal function, invasive procedures such as exchange transfusion or dialysis were required. In other cases, the condition was reversible within 3 to 6 days of stopping the NSAID and in these cases reappeared when the same NSAID was restarted.

NSAIDs may impair female fertility; withdrawal of NSAID therapy should be considered in women with difficulties conceiving or who are undergoing investigation of infertility.

Use of NSAIDs during labor and delivery have been show to inhibit prostaglandin synthesis, cause delayed parturition, and increase the incidence of stillbirth.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

Contraindicated last trimester of pregnancy
NSAIDs should be avoided at 20 weeks gestation and later

US FDA pregnancy category: Not assigned

Risk Summary: Nonsteroidal anti-inflammatory drugs (NSAIDs) use in pregnant women at 30 weeks gestation and later may cause premature closure of the fetal ductus arteriosus; NSAID use at 20 weeks gestation or later may cause fetal renal dysfunction leading to oligohydramnios and, in some cases, neonatal renal impairment.

Comments:
-NSAID use in pregnancy prior to 20 weeks gestation should be based on a benefit-risk assessment; some authorities recommend avoiding NSAIDs throughout pregnancy whenever possible.
-If NSAID use is necessary between 20- and 30-weeks' gestation, limit use to the lowest effective dose for the shortest duration possible; ultrasound monitoring of amniotic fluid should be considered if NSAID use extends beyond 48 hours; if oligohydramnios occurs, discontinue NSAID and treat appropriately.
-NSAID use is not recommended in women attempting to conceive as it may impair female fertility.

See references

Use is generally considered acceptable; according to some manufacturers, use is not recommended.

Excreted into human milk: Yes (famotidine, ibuprofen)

Comments: The effects in the nursing infant are unknown.

Transient growth depression was observed in animal studies at maternotoxic doses of at least 300 times the usual human dose of famotidine. Histamine H2-receptor blockade is known to stimulate prolactin secretion; while this usually does not occur with famotidine, rare cases of hyperprolactinemia and galactorrhea have been reported. Due to both ibuprofen and famotidine being used in infants at doses much higher than those excreted in breast milk, adverse effects in breastfed infants are unlikely to occur.

See references