This sheet is about exposure to omeprazole or esomeprazole in pregnancy or while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.

What is omeprazole and esomeprazole?

Omeprazole is a medication used to treat heartburn, stomach ulcers, and acid reflux (also known as GERD, or gastroesophageal reflux disease). It belongs to a group of medicines called proton pump inhibitors (PPIs) that reduce acid released by the stomach.

A common brand for omeprazole is Prilosec®. Omeprazole is combined with sodium bicarbonate in a medication called Aegeriid®. Esomeprazole (Nexium®) contains the same active medication as omeprazole. Esomeprazole is also a PPI and is used for the same conditions as omeprazole. These two drugs act in the body in a similar way. MotherToBaby has a fact sheet on PPIs at https://mothertobaby.org/fact-sheets/proton-pump-inhibitors/pdf/.

Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take this medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.

I take omeprazole or esomeprazole. Can it make it harder for me to get pregnant?

It is not known if taking omeprazole or esomeprazole can make it harder to get pregnant. Studies done in animals show no evidence that omeprazole or esomeprazole could make it harder to get pregnant.

Does taking omeprazole or esomeprazole increase the chance for miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. Limited studies have shown that taking omeprazole or esomeprazole during pregnancy is not expected to increase the chance for miscarriage.

Does taking omeprazole or esomeprazole increase the chance of birth defects?

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Omeprazole (which has the same active medication as esomeprazole) is the best studied of the PPIs. Multiple studies, including over 5000 people, did not show an increase in the chance for birth defects.

Does taking omeprazole or esomeprazole in pregnancy increase the chance of other pregnancy related problems?

Limited studies have shown that taking omeprazole or esomeprazole is not likely to cause other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).

Does taking omeprazole or esomeprazole in pregnancy affect future behavior or learning for the child?

Based on studies reviewed, it is not known if omeprazole or esomeprazole use in a pregnancy can cause behavior or leaning issues for the child. A few studies reported that taking PPIs in pregnancy might increase the chance for asthma in childhood. These studies have some flaws that make it hard to link medication use with childhood asthma. In another study, taking omeprazole in pregnancy did not increase the chance of asthma during childhood. It is not known if the use of PPIs during pregnancy increases the chance of childhood asthma.

Breastfeeding while taking omeprazole or esomeprazole:

These medications enter the breastmilk at low levels and are usually broken down by baby’s stomach acid and do not enter their blood stream. Limited data shows that doses of 20mg of omeprazole or 10mg or esomeprazole daily produce low levels of these medications in milk and are not expected to be harmful to the baby. Be sure to talk to your healthcare provider about all of your breastfeeding questions.

If a male takes omeprazole or esomeprazole, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?

There are limited studies looking at the effects of using PPIs on male fertility. One study found that when PPIs were used for any period between 6 and 12 months, sperm count was decreased. However, a more recent study looking at the effects of PPI use on male fertility did not support these findings, with their study showing that PPI use was not associated with any negative impact on sperm count or quality. In general, exposures that fathers or sperm donors have are unlikely to increase the risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.

Selected References:

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• Gill SK et al. 2009. The safety of proton pump inhibitors (PPIs) in pregnancy: a meta-analysis. Am J Gastroenterol; 104(6): 1541-1545. [PubMed: 19491869]
• Hastie R, et al. 2019. Proton pump inhibitors and preeclampsia risk among 157 720 women: a Swedish population register–based cohort study. Hypertension; 73(5):1097–103. [PubMed: 30827143]
• Huijgen NA. 2016. Are proton-pump inhibitors harmful for the semen quality of men in couples who are planning pregnancy? Fertility and Sterility, 106(7), 1666-1672. [PubMed: 27743698]
• Kallen B. 1998. Delivery outcome after the use of acid-suppressing drugs in early pregnancy with special reference to omeprazole. Br J Obstet Gynaecol; 105:877-881. [PubMed: 9746381]
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• Mumtaz, N, et al. Harmful Consequences of Proton Pump Inhibitors on Male Fertility: An Evidence from Subchronic Toxicity Study of Esomeprazole and Lansoprazole in Wistar Rats. International Journal of Endocrinology. [PMC free article: PMC9072022] [PubMed: 35529080]
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“OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.