Pregnancy and ACE Inhibitors or ARBs: Fetal Risks and Safe Alternatives
Jan, 6 2026
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When you're pregnant and need to manage high blood pressure, the wrong medication can put your baby at serious risk. ACE inhibitors and ARBs - commonly prescribed for hypertension - are not safe during pregnancy. Even if you’re not trying to get pregnant, if you’re taking one of these drugs, you need to know the facts now.
Why ACE Inhibitors and ARBs Are Dangerous in Pregnancy
ACE inhibitors (like lisinopril, enalapril, and captopril) and ARBs (like losartan and candesartan) work by blocking a system in your body called the renin-angiotensin-aldosterone system, or RAAS. That system helps control blood pressure. But in a developing baby, it’s also essential for kidney growth and amniotic fluid production. When a pregnant person takes these drugs, the baby’s kidneys can stop working properly. This leads to low amniotic fluid (oligohydramnios), which can cause lung underdevelopment, limb deformities, and skull abnormalities. The baby’s blood pressure can drop dangerously low. Their kidneys may fail. In severe cases, it leads to stillbirth or neonatal death. Studies show these risks aren’t rare. A 2011 study published in Obstetrics & Gynecology International found that women taking ACE inhibitors or ARBs during pregnancy had a 25.4% miscarriage rate - more than double the rate in healthy controls. Babies exposed to these drugs were also born, on average, 1.8 weeks earlier and weighed about 350 grams less. And here’s something many people still get wrong: it’s not just the second and third trimesters that are dangerous. A 2020 meta-analysis in Pharmacology Research & Perspectives showed that even exposure in the first trimester increases the risk of poor outcomes. There’s no safe window.ARBs May Be Even Riskier Than ACE Inhibitors
While both classes are off-limits during pregnancy, evidence suggests ARBs carry a higher risk than ACE inhibitors. The American Heart Association’s 2012 review found that babies exposed to ARBs had worse outcomes - including more severe kidney damage and higher rates of neonatal complications - compared to those exposed to ACE inhibitors. This matters because some patients assume if they took an ACE inhibitor early in pregnancy and stopped, they’re fine. But if they were on an ARB like losartan, the risk profile is more serious. The same goes for candesartan - it’s particularly linked to fetal toxicity. Both need to be stopped immediately.What to Take Instead: Safe Alternatives for Hypertension in Pregnancy
You still need to control your blood pressure - but safely. Three medications are well-studied and recommended as first-line options during pregnancy:- Labetalol: A beta-blocker that also blocks alpha receptors. It’s the most commonly used drug in pregnancy because it works quickly, has minimal side effects on the baby, and has decades of safety data. Doctors often start with 100 mg twice daily and increase as needed, up to 2,400 mg per day.
- Methyldopa: This has been used since the 1970s and has the longest track record of safety in pregnancy. It’s taken orally, usually starting at 250 mg twice daily, and can be increased up to 3,000 mg daily. It doesn’t cross the placenta much, so it rarely affects the baby’s heart rate or growth.
- Nifedipine: A calcium channel blocker that’s effective for high blood pressure. It’s often used as a second-line option, especially if labetalol or methyldopa aren’t enough. But it’s not ideal for women with heart failure or certain heart conditions because it can weaken heart muscle contractions.
What Happens If You’re Already Pregnant and Taking One of These Drugs?
If you find out you’re pregnant and you’re on an ACE inhibitor or ARB, don’t panic - but act fast. Stop taking the drug immediately. Call your doctor the same day. Do not wait for your next appointment. Your provider will switch you to one of the safe alternatives listed above, usually within 24 to 48 hours. They’ll likely order an ultrasound to check amniotic fluid levels and assess fetal kidney function. In many cases, if the drug is stopped early enough, the baby can recover without lasting damage - especially if exposure was limited to the first few weeks. But if you’ve been taking it past the first trimester, your care team will monitor you closely for signs of fetal distress. That might mean more frequent ultrasounds, non-stress tests, and possibly early delivery if complications arise.Planning a Pregnancy? Here’s What You Need to Do Now
If you’re taking an ACE inhibitor or ARB and thinking about getting pregnant, don’t wait until you miss a period. Talk to your doctor before you try to conceive. Major medical groups - including the American College of Obstetricians and Gynecologists (ACOG), the American Heart Association (AHA), and the Society of Obstetricians and Gynaecologists of Canada (SOGC) - all agree: switch to a safer medication before pregnancy begins. That’s not a suggestion. It’s a standard of care. Your doctor will help you transition slowly. You won’t just stop your current drug cold turkey - that could cause a dangerous spike in blood pressure. Instead, they’ll start you on labetalol or methyldopa, gradually reduce the ACE inhibitor or ARB, and make sure your blood pressure stays stable throughout the change. Also, if you’re on birth control, make sure it’s reliable. Some forms of contraception - like the pill - can interact with blood pressure meds. Talk to your provider about the best combo for you.
Why Do These Mistakes Still Happen?
Despite clear guidelines, about 1.2% of pregnancies in women with chronic hypertension still involve exposure to ACE inhibitors or ARBs, according to FDA data from 2021. Why? One reason: many patients don’t realize their blood pressure medication is risky. They see it as just a “pill for high blood pressure” and don’t connect it to pregnancy. Another reason: some providers don’t consistently ask about pregnancy plans or fail to document contraception use. In New Zealand, Medsafe’s 2024 advisory now requires doctors to explicitly ask patients: “Are you planning to become pregnant?” and “Are you currently pregnant?” before prescribing these drugs. That’s the kind of practice that saves lives.What You Should Do Right Now
If you’re a woman of childbearing age and take an ACE inhibitor or ARB:- Check your pill bottle. Does it say “lisinopril,” “enalapril,” “losartan,” or “candesartan”? If yes, note the name.
- Ask yourself: Have I been told this is unsafe in pregnancy? If not, you need to ask.
- Schedule a call or appointment with your doctor. Don’t wait. Say: “I’m concerned about pregnancy and this medication. What are my safe options?”
- If you’re trying to get pregnant - or think you might be - stop taking the drug and switch to a safe alternative immediately.
Frequently Asked Questions
Can I take ACE inhibitors or ARBs if I’m trying to get pregnant?
No. Both ACE inhibitors and ARBs are strictly contraindicated during pregnancy - even before you know you’re pregnant. If you’re planning to conceive, switch to a safer medication like labetalol or methyldopa at least 3 months before trying. Your doctor can help you make the transition safely.
What if I took an ACE inhibitor in the first trimester and then stopped?
Stop taking it immediately and contact your OB-GYN or maternal-fetal medicine specialist. An ultrasound will be done to check amniotic fluid levels and fetal kidney function. While early exposure carries risk, many babies recover if the drug is stopped quickly. The longer you take it, the higher the risk - especially past week 12.
Are there any exceptions - like low doses or short-term use?
No. There are no safe doses or safe durations of ACE inhibitors or ARBs during pregnancy. Even a single dose can interfere with fetal development. The risk isn’t linear - it’s absolute. No medical organization supports their use at any stage.
Is it safe to breastfeed while taking labetalol or methyldopa?
Yes. Both labetalol and methyldopa are considered safe during breastfeeding. Only tiny amounts pass into breast milk, and studies show no negative effects on infant growth or development. Nifedipine is also considered low-risk for nursing babies.
How do I know if my doctor is up to date on these guidelines?
Ask directly: “Based on current ACOG and AHA guidelines, is this medication safe in pregnancy?” If they hesitate or say “it’s probably fine,” seek a second opinion. Any provider treating pregnant patients should know these guidelines cold. If they don’t, they’re not following current standards.
Elen Pihlap
January 7, 2026 AT 21:15i took losartan for 3 months before i knew i was pregnant and now i’m terrified every time my baby moves. i didn’t even know it was dangerous. my doctor never told me. why is this not on the pill bottle??
Emma Addison Thomas
January 8, 2026 AT 06:40thank you for writing this. in the uk, we’re still seeing too many women prescribed these meds without proper counseling. it’s not just about awareness-it’s about systemic failure. doctors need to be held accountable.
Anastasia Novak
January 8, 2026 AT 09:04oh my god. i just checked my prescription. it’s candesartan. i’ve been on it for 2 years. i thought it was just a fancy blood pressure pill. i’m 6 weeks pregnant and i’m sobbing in my car right now. why didn’t anyone warn me?? this is medical negligence. i’m calling my lawyer tomorrow.
Jonathan Larson
January 9, 2026 AT 16:06This is a critically important public health message. The renin-angiotensin system is not merely a regulatory pathway for blood pressure; it is a fundamental architect of fetal organogenesis. The teratogenic potential of ACE inhibitors and ARBs is not speculative-it is empirically established, reproducible, and documented across multiple large-scale cohort studies. To delay intervention is to risk irreversible harm. Proactive medication substitution prior to conception is not merely prudent-it is ethically obligatory.
Alex Danner
January 9, 2026 AT 21:08just want to add: if you’re on one of these meds and you’re not trying to get pregnant, use reliable birth control. not just the pill-some BP meds mess with hormonal contraceptives. iuds or implants are way safer. also, if your doctor says "it’s probably fine," they’re wrong. period.
Sai Ganesh
January 11, 2026 AT 15:47in india, many women are prescribed these drugs because they're cheaper. no one tells them about pregnancy risks. we need community health workers to spread this info. this isn't just a western problem.
Paul Mason
January 13, 2026 AT 13:22lol you people are freaking out over a pill. my cousin took lisinopril while pregnant and her kid is fine. you’re all overreacting. it’s not like you’re injecting lead into your belly.
Katrina Morris
January 14, 2026 AT 13:57i had no idea this was a thing. i thought all blood pressure meds were safe during pregnancy. i’m 8 weeks and on lisinopril. i’m gonna call my dr right now. thank you for this
Anthony Capunong
January 16, 2026 AT 11:04why are we letting foreign drug companies dictate our healthcare? these meds are banned in europe but still sold here. it’s all about profit. america is a medical wasteland.
Ayodeji Williams
January 17, 2026 AT 05:18bro i took losartan for 4 months and my baby is a genius now 😎 no big deal. stop scaremongering. also why are you all so anxious?? 🤷♂️
Kyle King
January 17, 2026 AT 16:10this is all a hoax. big pharma made up the risks so they could sell you labetalol at 5x the price. the FDA is in on it. my cousin’s OB-GYN said the same thing… then she got fired for "promoting fear."
Kamlesh Chauhan
January 18, 2026 AT 04:32ok but what about the 2023 study that says ARBs are fine if you take them before week 8? you guys are ignoring the data. also why is everyone so dramatic about a pill