Lisinopril is a medication frequently prescribed to manage high blood pressure, also known as hypertension, and to treat heart failure. It belongs to a class of drugs called angiotensin-converting enzyme (ACE) inhibitors. This medication works by relaxing blood vessels, which in turn lowers blood pressure and helps the heart pump blood more efficiently throughout the body. Lisinopril is also used following a heart attack to improve survival rates.
Why Lisinopril Poses a Risk in Pregnancy
Lisinopril is harmful during pregnancy due to its direct interference with the fetal renin-angiotensin system, which regulates blood pressure and kidney development. This medication works by blocking the conversion of angiotensin I to angiotensin II, a hormone that normally causes blood vessel constriction and increases sodium and water retention. This inhibition can disrupt the normal physiological processes in the developing fetus.
The risk to the fetus is highest when lisinopril is used during the second and third trimesters of pregnancy. During these later stages, the fetal kidneys are more developed and rely on the renin-angiotensin system for proper function and fluid balance. However, caution is advised throughout all trimesters, as exposure even in the first trimester may carry risks, although they are less documented than later exposure.
Specific Dangers to Fetal Development
Lisinopril exposure can lead to severe, potentially fatal adverse effects on the developing fetus. One danger is oligohydramnios, characterized by abnormally low amniotic fluid. This reduction results from decreased fetal kidney function, as fetal kidneys produce amniotic fluid.
Oligohydramnios can lead to several complications, including poor lung development (lung hypoplasia). The reduced fluid volume restricts fetal movement and lung expansion, impairing proper lung maturation. Additionally, low amniotic fluid can contribute to skeletal malformations, such as limb contractures and craniofacial deformation, due to external compression.
Lisinopril can also directly affect fetal kidney development, leading to conditions like renal tubular dysgenesis or fetal renal failure. This can result in neonatal anuria (absence of urine production in the newborn), potentially requiring interventions like peritoneal dialysis. Cases of neonatal hypotension and death have been reported in infants exposed to ACE inhibitors in utero.
Guidance for Pregnant Individuals on Lisinopril
If pregnant or planning pregnancy while on lisinopril, immediate consultation with a healthcare provider is essential. Do not discontinue the medication without medical guidance, as sudden cessation can pose risks to the mother. Healthcare providers will assess individual needs and develop a safe transition plan.
The process typically involves switching to alternative antihypertensive medications considered safer for use during pregnancy. Recommended alternatives include methyldopa, labetalol, and nifedipine. Methyldopa is often a first-line choice for mild to moderate hypertension due to its long safety record. Labetalol, a mixed alpha- and beta-blocker, is commonly used for moderate to severe hypertension, while nifedipine, a calcium channel blocker, can be used for severe hypertension.
Close medical monitoring throughout pregnancy is also important. This includes regular blood pressure checks to ensure adequate control and frequent prenatal visits to assess both maternal and fetal health. Ultrasounds may monitor fetal growth and amniotic fluid levels, and screen for potential birth defects, particularly those affecting the skull bones and kidneys.
Lisinopril Use While Breastfeeding
Lisinopril use while breastfeeding might be acceptable, but consultation with a healthcare provider is advised. While information on lisinopril in breast milk is limited, it is generally believed to be a small amount. Research indicates that levels in breastmilk are low, and amounts ingested by the infant are expected to be small, likely not causing adverse effects.
However, the effects on breastfed infants are not fully known, as comprehensive studies are limited. There is a very small theoretical risk it could lower the baby’s blood pressure, particularly in premature infants or those under two months of age. Mothers should discuss their situation with their healthcare provider for personalized advice and to consider alternative ACE inhibitors like enalapril, which has more documented safety data in breastfeeding.