Naproxen While Trying to Conceive: What One PRESTO Study Found

If naproxen helps your period pain and you are trying to conceive, bring it into your pregnancy-planning discussion. MotherToBaby’s¹ May 2026 fact sheet says it is not known whether naproxen makes pregnancy harder to achieve. Some studies suggest interference with ovulation, potentially more likely with frequent or long-term use.¹

What PRESTO measured

PRESTO enrolled 2,573 women aged 21–45 in the US and Canada. After exclusions, including those already trying for more than six cycles, 1,763 were analyzed, with follow-up up to twelve months.²

Baseline naproxen use had an adjusted fecundability ratio of 0.78 (95% confidence interval 0.64–0.97) versus no painkiller use. This compares conception probability per cycle; it does not mean a 78% pregnancy chance or permanent infertility.²

The NICHD-funded study reported no author conflicts. Medicine use and pregnancies were self-reported, exact cycle timing was unrecorded, and reasons for each medicine were incompletely captured. Pain or an underlying condition could partly explain the association despite adjustment.²

A monthly association cannot give you safe cycle days

The study’s missing timing information matters when someone offers a simple rule about which days to avoid naproxen. These data cannot establish a personalized schedule around ovulation. Ask the clinician how your pain pattern and pregnancy plans affect the choice of treatment.

MotherToBaby¹ discusses possible effects on egg release, including a follicle not rupturing to release its egg, while emphasizing that the overall fertility effect remains uncertain.¹ This is a possible mechanism to discuss, rather than proof that it happened in your cycle.

Review the pain and the medicine together

Current NHS³ guidance lists trying to get pregnant among the circumstances in which naproxen may not be suitable. It also identifies period pain among its uses.³ Tell the clinician both parts: why you need it and that you are planning pregnancy.

Bring these particulars:

• The active ingredient and strength, not just the brand name.
• The number of tablets and days used in a typical month.
• Whether use is limited to bleeding days or also occurs between periods.
• The pain location, severity and what it stops you doing.
• Any other painkillers, migraine products or prescription treatments.

Ask: “Can we review why I need this pain relief and agree on an option and schedule that fit trying to conceive?” If pain keeps you home, wakes you or repeatedly interrupts work, describe that impact rather than reducing the conversation to whether a tablet is allowed.

Do not replace naproxen by stacking another anti-inflammatory on top. NHS³ guidance says not to take it with other NSAIDs such as ibuprofen or aspirin because that increases serious side-effect risk.³ A pharmacist can check the ingredients in combination products.

If a pregnancy test is positive

Contact your clinician or pharmacist to review treatment. NHS³ guidance advises avoiding naproxen during pregnancy unless a doctor or pharmacist recommends it.³ MotherToBaby¹ advises discussing medicine changes with healthcare professionals, including the benefits of treating the underlying condition.¹

Pregnancy safety is a separate question from a preconception study’s per-cycle association. The cohort above cannot assess an individual exposure after conception.

The Period book includes a Period Scorecard and visit script for recording pain, cycle changes and their impact. Bring those notes with the medicine details so the appointment addresses both symptom control and your pregnancy plans.