This sheet is about exposure to losartan in pregnancy and while breastfeeding. This information is based on available published studies. It should not take the place of medical care and advice from your healthcare provider.
What is losartan?
Losartan is part of a group of medications called angiotensin II receptor antagonists (also known as angiotensin receptor blockers (ARBs)). Losartan has been used to treat high blood pressure, protect the kidneys in people with diabetes, and lower the chance of cerebrovascular accident (when the supply of blood to the brain is reduced or blocked). A brand name for losartan is Cozaar®. Losartan is also available in combination with a diuretic called hydrochlorothiazide under the brand name Hyzaar®.
It is usually recommended that women who are pregnant stop taking losartan under their healthcare provider’s guidance. 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 am taking Losartan, but I would like to stop taking it before getting pregnant. How long does the drug stay in my body?
The time it takes the body to metabolize (to process) medication is not the same for everyone. In healthy non-pregnant adults, it takes up to 2 days, on average, for most of the Losartan to be gone from the body.
I take losartan. Can it make it harder for me to get pregnant?
It is not known if losartan can make it harder to get pregnant. One animal study did not find effects on fertility (ability to get pregnant).
Does taking losartan increase the chance for miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if losartan increases the chance for miscarriage.
Does taking losartan increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like Losartanm might increase the chance of birth defects in a pregnancy.
Losartan has not been well studied for use during pregnancy. It is not known if losartan can increase the chance of birth defects when used in the first trimester of pregnancy. There are case reports with typical outcomes after first trimester exposure to losartan when the medication was not used throughout pregnancy. One small study looked at 20 pregnancies exposed to the class of ARB medications. The study reported that 1 infant had craniosynostosis (when the bones in the skull join together too early) and another had inguinal hernia (when soft tissue bulges through a weak place in the belly muscles). Some of the women in this study had diabetes, which has also been linked to an increased chance of birth defects. It is not known if the medication taken, or other factors caused the reported birth defects.
Using losartan in the 2nd and 3rd trimesters can increase the chance of other pregnancy complications, such as low amniotic fluid (the fluid that surrounds the baby). Low amniotic fluid levels can cause birth defects. This is discussed in more detail below.
Does taking losartan in pregnancy increase the chance of other pregnancy-related problems?
Losartan use in the 2nd and/or 3rd trimester of pregnancy can cause other pregnancy-related problems, such as low levels of amniotic fluid (called oligohydramnios). Low levels of amniotic fluid can lead to poor lung and skull development, joint contractures (joints become stiff and unable to move), and growth restriction in the fetus. Oligohydramnios can also increase the need for an early delivery through induction of labor or C-section. In some cases, oligohydramnios could cause fetal demise.
Low blood pressure, kidney disease, and kidney failure have also been reported in babies exposed to losartan during pregnancy. In some cases, the affected infant died from these complications.
Because of these possible complications, it is usually recommended that women who are pregnant stop taking losartan under their healthcare provider’s guidance. It is important to talk with your healthcare provider before you stop taking losartan. They can talk with you about the best way to treat your condition during pregnancy. Some untreated conditions can also increase risks to a pregnancy.
Does taking losartan in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if losartan can cause behavior or learning issues for the child.
What screenings or tests are available to see if my pregnancy has birth defects or other issues?
Prenatal ultrasounds can be used to screen for some birth defects. Ultrasound can also be used to track the growth of the pregnancy. Talk with your healthcare provider about any prenatal screenings or testing that are available to you. There are no tests available during pregnancy that can tell how much effect here could be on future behavior or learning.
Breastfeeding while taking losartan:
Losartan has not been studied in humans for use during breastfeeding. Information from animal studies suggest that losartan passes into milk and could affect the kidneys of the nursing baby. The product label for losartan recommends women who are breastfeeding not use this medication. But the benefit of using losartan may outweigh possible risks. Your healthcare providers can talk with you about using losartan and what treatment is best for you. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man takes losartan, could it affect fertility or increase the chance of birth defects?
Studies have not been done to see if losartan could affect a man’s fertility (ability to get a woman pregnant) or increase the chance of birth defects. In general, exposures that men 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/.
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