Pregnancy and ACE Inhibitors or ARBs: Fetal Risk and Safe Alternatives

When you're pregnant and need to manage high blood pressure, the last thing you want is to accidentally harm your baby. Yet, many women are still prescribed ACE inhibitors or ARBs before they even know they're pregnant. These common blood pressure medications-like lisinopril, enalapril, and losartan-are not just risky during pregnancy. They can cause serious, sometimes deadly, damage to the developing fetus. The truth is, there is no safe time to take them if you're expecting. And if you're planning to get pregnant, you need to act now.

Why ACE Inhibitors and ARBs Are Dangerous in Pregnancy

ACE inhibitors and ARBs work by blocking a system in your body called the renin-angiotensin-aldosterone system (RAAS). That’s fine for adults-it helps lower blood pressure. But in a developing baby, that same system is critical. It helps the kidneys form, keeps amniotic fluid at the right level, and supports healthy blood flow to the placenta. When you block it, you’re not just lowering your own blood pressure-you’re shutting down your baby’s development.

The results are devastating. Studies show that exposure to these drugs during pregnancy leads to:

• Fetal kidney failure
• Severely low amniotic fluid (oligohydramnios)
• Skull bone defects
• Low birth weight (on average, 350 grams less than babies not exposed)
• Premature birth (nearly two weeks earlier on average)
• Stillbirth and neonatal death

Even more alarming: a 2020 meta-analysis of 72 studies found that exposure in the first trimester still increases the risk of miscarriage and poor outcomes. That’s a big shift from older beliefs that the first three months were “safe.” They’re not. The American Heart Association calls this pattern “fetal renin-angiotensin system blockade syndrome”-a collection of life-threatening complications that can start before you even feel pregnant.

ARBs Are Even Riskier Than ACE Inhibitors

You might think all blood pressure meds in this class are equally dangerous. They’re not. While both ACE inhibitors and ARBs are absolutely off-limits during pregnancy, data shows ARBs like losartan and candesartan carry an even higher risk. The American Heart Association’s 2012 review found that babies exposed to ARBs had worse outcomes than those exposed to ACE inhibitors-even when the exposure happened at the same stage of pregnancy.

Why? ARBs block the angiotensin II receptor more completely and for longer. That means the fetal RAAS system gets hit harder and for a longer duration. The result? More severe kidney damage, more profound drops in amniotic fluid, and higher rates of neonatal complications. If you’re on an ARB and find out you’re pregnant, don’t wait. Talk to your doctor immediately.

What Happens If You’re Already Taking One?

If you’re on lisinopril, enalapril, ramipril, or any ARB and just found out you’re pregnant, here’s what you need to do:

1. Stop taking the medication immediately.
2. Call your doctor or OB-GYN within 24 hours.
3. Do not switch to another blood pressure pill on your own.

This isn’t about panic-it’s about speed. The longer you stay on these drugs, the greater the risk. But stopping suddenly without a replacement can also be dangerous. Your blood pressure could spike, which brings its own risks to both you and your baby. That’s why you need professional guidance.

Your doctor will switch you to a pregnancy-safe alternative. The two most trusted options are labetalol and methyldopa.

Safe Alternatives for Blood Pressure in Pregnancy

You don’t have to go without treatment. There are proven, safe options that have been used for decades in pregnant women.

• Labetalol: This is the first-line choice for most doctors. It’s a beta-blocker that also relaxes blood vessels. It’s been used safely since the 1970s. Starting dose is usually 100mg twice a day, and it can be increased up to 2,400mg daily if needed. It doesn’t cross the placenta in large amounts, and studies show no increased risk of birth defects or developmental delays.
• Methyldopa: This is the oldest and most studied blood pressure medication for pregnancy. It’s been used since the 1970s and has the longest safety record. It works by calming the central nervous system. Typical starting dose is 250mg twice daily, with a maximum of 3,000mg per day. It’s especially good for women with chronic hypertension who need long-term control.
• Nifedipine: A calcium channel blocker, this is often used as a second-line option. It’s effective and safe for most women, but it’s not recommended if you have heart failure or certain heart conditions because it can weaken heart contractions.

These drugs don’t just keep your blood pressure in check-they help protect your baby’s organs, reduce the risk of preeclampsia, and improve your chances of carrying to term.

What About Before You Get Pregnant?

If you’re not pregnant yet but planning to be, this is your window to act. Don’t wait until you miss your period.

Major medical groups-including the American College of Obstetricians and Gynecologists (ACOG), the American Heart Association, and Health New Zealand-agree: Switch before conception.

Here’s what to do:

• If you’re on an ACE inhibitor or ARB, schedule a preconception visit with your doctor or OB-GYN.
• Ask for a full review of your medications.
• Discuss your blood pressure goals and how to manage them safely before pregnancy.
• If you’re sexually active and not using contraception, your doctor should be discussing pregnancy risks with you-no matter your age.

The U.S. Food and Drug Administration (FDA) and Medsafe (New Zealand) both require these warnings on packaging. But warnings don’t help if they’re not heard. In 2021, the FDA reported that 1.2% of pregnancies in women with chronic hypertension still involved exposure to ACE inhibitors or ARBs. That’s not because doctors are careless-it’s because the system isn’t catching these cases early enough.

How to Make Sure You’re Protected

You can’t rely on memory or assumptions. Here’s how to protect yourself:

• Keep a medication list-write down every pill you take, including over-the-counter and supplements. Bring it to every appointment.
• Ask your pharmacist every time you fill a prescription: “Is this safe if I get pregnant?”
• Use a pregnancy test before starting any new blood pressure medication if you’re sexually active and not on reliable contraception.
• Set a reminder on your phone: “Check meds if planning pregnancy.”

If you’re on a long-term medication for high blood pressure, your doctor should be reviewing it every 6 to 12 months. Don’t wait for your annual checkup-ask sooner if you’re thinking about starting a family.

What If You’re Already Pregnant and Took One?

If you took an ACE inhibitor or ARB before you knew you were pregnant, don’t blame yourself. Many women do. The key is to act quickly and get the right care.

Your doctor will likely order:

• An ultrasound to check amniotic fluid levels
• A detailed anatomy scan to look for kidney or skull abnormalities
• Regular blood pressure and fetal growth monitoring

Some babies exposed early still develop normally. Others need extra support after birth. Early detection gives you the best shot at a healthy outcome. The goal isn’t to scare you-it’s to empower you with information so you can make informed decisions.

Global Consensus: No Exceptions

As of 2025, every major medical organization in the world agrees: ACE inhibitors and ARBs have no place in pregnancy. Not in the first trimester. Not in the second. Not in the third. Not even if your blood pressure is high. There are safe alternatives. You don’t need to risk your baby’s life.

Organizations like ACOG, the Society of Obstetricians and Gynaecologists of Canada, and the World Health Organization all list these drugs as strictly contraindicated. Even the European Medicines Agency and Medsafe in New Zealand have issued urgent advisories. This isn’t a debate. It’s settled science.

What You Can Do Today

If you’re taking an ACE inhibitor or ARB:

• Don’t stop cold turkey-call your doctor.
• Ask for a safe replacement.
• Get a pregnancy test if you’re sexually active and not using contraception.
• If you’re planning pregnancy, schedule a preconception visit now.

Your health matters. Your baby’s health matters more. There’s no reason to wait.