Prilosec vs. Nexium during pregnancy

How do the options compare?

The two are compared on potency per milligram, how quickly each one acts, and how many counted pregnancies sit behind each individual name rather than behind the class as a whole.

• Omeprazole and esomeprazole share one pregnancy fact sheet, and the available information does not suggest a higher chance of birth defects with either, nor an expected rise in miscarriage. 1
• Omeprazole has the deeper file: a pooled analysis of 534 exposed pregnancies gave a relative risk of 1.05 for malformations, while esomeprazole had no published human pregnancy data of its own when that review was written. 2
• Class-wide evidence has since caught up: across 2.7 million pregnancies, first-trimester proton pump inhibitor exposure showed a relative risk of 1.07 that disappeared in the sibling comparison, and the authors concluded the class is unlikely to be a major teratogen. 3
• Both drugs hit the same target, the stomach's H+/K+ pump at the final step of acid production, with effects beginning within an hour of a dose and peaking around two hours. 4
• On a standardized potency scale where omeprazole equals 1.00, esomeprazole scores 1.60, so milligram for milligram Nexium suppresses more acid, which is a dosing difference rather than a safety one. 5

Which option makes sense?

Nothing published separates them on safety, so the real difference is that omeprazole was counted first and esomeprazole is stronger per milligram, which makes switching a dose conversation rather than a safety one.

Disclosure: Pregnancy Smart offers a supplement that overlaps with one or more options above. This page describes the pregnancy evidence for each option on its own merits.