Fertility and Immunosuppressants: What You Need to Know Before Getting Pregnant

Feb, 19 2026

When you're managing a chronic autoimmune disease or have had an organ transplant, staying healthy often means taking immunosuppressants daily. But if you're thinking about starting a family, these same medications can raise serious questions: Can I get pregnant safely? Will my baby be at risk? Should I stop my meds? The answers aren't simple, and waiting until you're already pregnant is too late. The truth is, many people on immunosuppressants do have healthy babies-but only if they plan ahead.

Not All Immunosuppressants Are Created Equal

There's no one-size-fits-all answer when it comes to fertility and pregnancy. Different drugs have wildly different effects. Some are relatively safe, others carry clear risks, and a few should be avoided entirely if you're trying to conceive.

Azathioprine stands out as one of the safest options. Over 1,200 documented pregnancies in women taking this drug showed no increase in birth defects or miscarriage rates, according to a major 2000 study in JAMA Internal Medicine. It's often the go-to choice for women with lupus or rheumatoid arthritis who want to get pregnant.

On the other end of the spectrum, cyclophosphamide is a known fertility killer. In women, it can cause permanent ovarian damage-up to 70% of those who take cumulative doses over 7 grams per square meter of body surface lose their ability to conceive naturally. In men, it can lead to irreversible azoospermia (zero sperm count) in about 40% of cases. If you're on this drug and thinking about having kids, fertility preservation like egg or sperm freezing should be discussed before you start treatment.

Methotrexate, commonly used for psoriasis or rheumatoid arthritis, is embryotoxic. It can cause severe birth defects if taken during pregnancy. The rule? Stop it at least three months before trying to conceive. Even a single dose during early pregnancy can be dangerous.

For men, sulfasalazine is a surprise culprit. It cuts sperm counts by 50-60%, but here's the good news: the effect is reversible. Once you stop taking it, sperm numbers usually bounce back within three months. No need to panic-but do get a semen analysis if you've been on it for over a year.

Steroids, Transplant Drugs, and Hidden Risks

Corticosteroids like prednisone are often continued during pregnancy because stopping them can trigger disease flares. But they're not harmless. They can interfere with ovulation and sperm production, and they raise the risk of premature rupture of membranes by 15-20%. Still, for most patients, the benefits outweigh the risks when used at the lowest effective dose.

For transplant patients, drugs like ciclosporine and tacrolimus are common. Ciclosporine increases the chance of prematurity by about 25%. Tacrolimus? It bumps up the risk of gestational diabetes by 30-40%. Neither causes birth defects, but they require close monitoring during pregnancy. Blood sugar checks, frequent ultrasounds, and extra prenatal visits become part of the routine.

Sirolimus is another story. It's currently contraindicated during pregnancy. Early reports include seven pregnancies with three miscarriages and one baby born with structural abnormalities. There's not enough data to say it's safe-and the risks are too high to gamble on.

Chlorambucil, used in rare autoimmune cases, is even more concerning. The FDA classifies it as Category D, meaning there's clear evidence of fetal harm. Studies show it's linked to kidney malformations (8% of exposed babies), ureter defects (12%), and heart problems (15%). Breastfeeding is also off-limits if you're on this drug.

What About Newer Drugs? Belatacept and Beyond

The landscape is changing. Newer immunosuppressants like belatacept, used after kidney transplants, have shown promising early results. So far, three documented pregnancies in women taking belatacept led to healthy babies with no birth defects. But with only three cases, we can't call it safe yet. It's not recommended as a first-line option for those planning pregnancy-but for someone who can't tolerate other drugs, it might be an option under strict supervision.

One big problem: many older drugs were approved before regulators required testing for reproductive side effects. The FDA and EMA didn't demand studies on male fertility until recently. That means we're still playing catch-up. For example, we don't have solid data on how mycophenolate affects sperm quality long-term, or whether newer drugs like voclosporin impact fetal development.

Preconception Counseling Isn't Optional-It's Essential

You can't wing this. Waiting until you miss a period to talk to your doctor is a recipe for stress, uncertainty, and possibly harm. Experts agree: start the conversation at least 3-6 months before you plan to conceive.

Here’s what that conversation should include:

• Review every medication you're taking, including over-the-counter supplements
• Switch to safer alternatives if possible-azathioprine over cyclophosphamide, for instance
• For women: check ovarian reserve with AMH and FSH blood tests if you're over 30 or on high-risk drugs
• For men: get a semen analysis if you've been on sulfasalazine, cyclophosphamide, or similar drugs for over a year
• Ensure your disease is stable. Flares during pregnancy are dangerous for both you and the baby
• Discuss fertility preservation: egg freezing, sperm banking, or embryo cryopreservation

For transplant patients, coordination between your transplant team, rheumatologist, and fertility specialist is critical. One doctor can't manage everything. You need a team that talks to each other.

Monitoring During Pregnancy

If you do get pregnant, you're not off the hook. You'll need more frequent checkups. For kidney transplant patients, creatinine levels above 1.3 mg/dL before pregnancy raise the risk of preeclampsia. Monthly kidney function tests are standard.

Babies born to mothers on immunosuppressants may have lower B- and T-cell counts in their first year, making them more vulnerable to infections. That doesn't mean you shouldn't vaccinate them-just that you should work with your pediatrician to monitor their immune response. Live vaccines like MMR may need to be delayed.

For men: if you're on immunosuppressants, your partner doesn't need to avoid pregnancy. There's no evidence that sperm carrying these drugs causes birth defects. But if you're on drugs like cyclophosphamide, it's still wise to wait at least three months after stopping before trying to conceive-just to let new sperm develop.

What About Breastfeeding?

Some drugs pass into breast milk. Chlorambucil? Absolutely not. Cyclophosphamide? Only if you wait 3-4 hours after taking it. Azathioprine? Generally considered safe. Prednisone? Low doses are fine. Always check with your doctor before nursing. The key is timing: take your dose right after feeding, not before.

Long-Term Gaps in Knowledge

We know a lot more than we did in 2000, but there are still big blind spots. We don't have long-term data on how children exposed to newer drugs like belatacept or voclosporin develop mentally or immunologically. We don't have enough studies on paternal exposure. And we still lack registries that track outcomes systematically.

That's why experts are pushing for better research: national pregnancy registries, standardized sperm testing protocols, and longer follow-up studies on exposed children. Until then, caution and careful planning remain your best tools.

Bottom Line: Plan Early, Stay Informed

Fertility isn't off-limits if you're on immunosuppressants-but it requires strategy. You can't rely on luck or hope. You need a plan, a team, and accurate information. Whether you're a woman with lupus, a man on sulfasalazine, or a transplant recipient, your path to parenthood is possible. But it starts with a conversation-long before you stop using birth control.