Is diclofenac (Nonsteroidal Anti-Inflammatory Drug (NSAID)) safe to use during the first trimester of pregnancy?

Diclofenac Use During First Trimester

Diclofenac can be used during the first trimester of pregnancy when clinically necessary, as current evidence shows no increased risk of miscarriage or congenital malformations. 1

Safety Profile in First Trimester

Early pregnancy exposure to diclofenac does not increase the risk of teratogenicity or spontaneous abortion. 1 The 2025 EULAR guidelines explicitly state that data for early pregnancy NSAID exposure show no evidence of increased risk of miscarriage or teratogenicity, with the most reassuring data available for ibuprofen, followed by diclofenac. 1

A prospective observational cohort study of 260 women exposed to diclofenac in the first trimester found no increased rate of major birth defects (1.8% vs. 3.1% in controls; adjusted OR 0.59,95% CI 0.17-2.08) and no increased risk of spontaneous abortion (adjusted HR 0.90,95% CI 0.56-1.46). 2

Critical Prescribing Parameters

When diclofenac is needed during the first trimester:

• Use the lowest effective dose for the shortest possible duration (ideally 7-10 days maximum). 1
• Diclofenac crosses the placenta readily during the first trimester, achieving fetal tissue concentrations similar to maternal serum levels. 3
• Consider switching to acetaminophen as first-line analgesic if planning pregnancy or once pregnancy is confirmed, as acetaminophen has the most extensive safety data. 4

Fertility Considerations

Women actively trying to conceive should discontinue diclofenac, as NSAIDs can interfere with ovulation by inducing luteinized unruptured follicle (LUF) syndrome, potentially reducing fertility. 1, 5 This effect is reversible upon discontinuation. 1

Gestational Age-Specific Restrictions

While first trimester use is relatively safe, strict gestational age cutoffs must be observed:

• First trimester (weeks 0-13): Can be used if needed with precautions outlined above 1
• Second trimester (weeks 14-28): Short-term use (7-10 days) acceptable, but avoid after week 20 if possible due to emerging fetal renal risks 1, 5
• After week 28: Absolute contraindication due to risk of premature ductus arteriosus closure and oligohydramnios 1, 6

Common Clinical Pitfalls

• Do not assume diclofenac is safe throughout pregnancy simply because first trimester use is acceptable—the risk profile changes dramatically after week 20 and especially after week 28. 5, 6
• Avoid chronic daily use even in the first trimester—limit to short courses for acute pain management. 1
• Screen for pregnancy before prescribing to women of reproductive age, and counsel about the need to discontinue by week 28 at the absolute latest. 6

Alternative Analgesics

If ongoing pain management is needed throughout pregnancy:

• Acetaminophen is the preferred first-line analgesic across all trimesters, though use the lowest effective dose for the shortest duration. 4
• Ibuprofen has slightly more reassuring safety data than diclofenac for first and second trimester use if an NSAID is required. 1, 7
• For chronic inflammatory conditions, consider pregnancy-compatible alternatives such as hydroxychloroquine, sulfasalazine, low-dose prednisone (≤5 mg/day), or azathioprine before conception. 1