Administration of NSAIDs during the latter part of pregnancy may cause premature closure of the fetal ductus arteriosus, fetal renal impairment, inhibition of platelet aggregation, and delay labor and delivery. There are no adequate and well controlled studies of diclofenac or other NSAIDs in pregnant women.

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.

The use of drugs known to inhibit cyclooxygenase/prostaglandin synthesis may impair female fertility; consider withdrawal of NSAIDs in women who have difficulties conceiving or who are undergoing investigation of infertility.

AU TGA pregnancy category C: Drugs which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible. Accompanying texts should be consulted for further details.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

US FDA pregnancy category D: There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

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

AU TGA pregnancy category: C
US FDA pregnancy category: C prior to 30 weeks gestation
US FDA pregnancy category: D starting at 30 weeks gestation

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 not recommended

Excreted into human milk: Yes

The effects in the nursing infant are unknown.

The data on excretion into breast milk is limited. One women receiving 150 mg daily had milk levels of 100 mcg/L, equivalent to an infant dose of about 0.03 mg/kg/day. Six mothers receiving 100 mg orally daily for 1 week postpartum had undetectable levels in their milk. While it does appear to pass in small amounts, some experts consider this drug to be acceptable during breast feeding, however other agents have more published information and may be preferred, especially when nursing a newborn or preterm infant.

See references