Fertility and Immunosuppressants: What You Need to Know Before Trying to Conceive

Trying to get pregnant while taking immunosuppressants isn’t something most people plan for. But for those managing autoimmune diseases or organ transplants, it’s a real and urgent question. You’re not alone. Thousands of people each year face this decision: keep controlling your condition, or pause meds to protect a future child. The truth? It’s possible to have a healthy pregnancy-but only if you know what you’re up against.

Not All Immunosuppressants Are Created Equal

Some drugs are safe. Others are dangerous. And some? They wreck your fertility before you even think about getting pregnant. It’s not a guesswork game. There’s hard data on each one.

Azathioprine is the gold standard when it comes to safety. Over 1,200 pregnancies tracked since 2000 showed no increase in birth defects or miscarriages. It’s the go-to for women and men planning a family. If you’re on something riskier, your doctor should be talking about switching to this one-well before conception.

Methotrexate, on the other hand, is a hard stop. It doesn’t just raise the risk of miscarriage-it causes severe birth defects. You need to stop it at least three months before trying to conceive. And no, waiting two months isn’t enough. Your body needs that full cycle to clear it out.

Cyclophosphamide is brutal. For women, it can permanently destroy ovarian function. Studies show 60-70% of women who take more than 7 grams per square meter of body surface area lose their ability to have biological children. For men, it can cause irreversible azoospermia-zero sperm-in 40% of cases. If you’re on this drug and want kids, talk to a fertility specialist before you even start. Egg or sperm freezing isn’t optional-it’s essential.

Sulfasalazine lowers sperm counts by 50-60%. It’s not permanent, but it’s real. And recovery takes up to three months after stopping. If you’re trying to conceive, your partner’s sperm count might be the missing piece.

Prednisone and other steroids don’t kill fertility, but they mess with hormones. They can throw off ovulation in women and lower testosterone in men. They also raise the risk of premature rupture of membranes by 15-20%. That means early labor. Not something you want to gamble with.

What About the Newer Drugs?

Newer immunosuppressants sound promising-but don’t be fooled by the hype.

Sirolimus is a red flag. Early reports show a 43% miscarriage rate in pregnant women taking it. That’s more than double the normal rate. Seven documented pregnancies included three first-trimester losses and one baby born with major structural problems. It’s still labeled contraindicated during pregnancy-and it should be.

Belatacept has a tiny but encouraging track record. Only three pregnancies have been reported so far, and all resulted in healthy babies. But three isn’t enough. It’s not yet considered safe. Until more data comes in, stick with proven options.

Chlorambucil is FDA Class D-meaning there’s clear evidence of harm. It’s linked to kidney defects in 8% of exposed babies, ureter problems in 12%, and heart issues in 15%. If you’re on this drug, pregnancy isn’t just risky-it’s medically discouraged. And breastfeeding? Absolutely not. The drug passes into breast milk.

Men’s Fertility Gets Overlooked

Most counseling focuses on women. But men matter too.

Over half the immunosuppressants used today were approved before regulators even asked: What does this do to sperm? That’s not a joke. It’s a gap in science. We’re still catching up.

The FDA now requires new drugs to be tested on at least 200 men in controlled trials. But older ones? No such luck. That means if you’re on a drug prescribed 10 or 15 years ago, there’s a good chance no one ever checked its effect on male fertility.

For men: get a semen analysis before starting any immunosuppressant. Do another one after 74 days-exactly one full sperm cycle. Then, after you stop the drug, test again at 13 weeks. That’s the only way to know if your sperm is recovering.

And yes, your partner’s pregnancy depends on your sperm health too. Don’t let this part slide.

Timing Is Everything

You can’t just stop a drug cold and hope for the best. Timing matters.

For methotrexate: stop 3 months before trying. No exceptions.

For cyclophosphamide: if you haven’t frozen eggs or sperm, don’t try to conceive. Period.

For azathioprine or prednisone: you can often stay on them. But you need monitoring. Your kidney function, blood pressure, and immune markers need to be stable before conception.

For transplant patients: your immunosuppression plan is a tightrope walk. Too little? Rejection risk. Too much? Higher chance of infection in your baby. Studies show newborns of mothers on tacrolimus have lower B- and T-cell counts-and a 2.3 times higher risk of infections in their first year.

Preconception counseling should happen 3 to 6 months before you start trying. That’s not a suggestion. It’s medical necessity. This isn’t about being cautious. It’s about survival-for you, your partner, and your future child.

What About Breastfeeding?

Some drugs are safe. Others are not.

Azathioprine passes into breast milk in tiny amounts. Most experts agree it’s safe to breastfeed while taking it-just watch your baby for signs of infection or low blood counts.

Chlorambucil? No. Don’t even think about it. It’s in the milk, and it’s dangerous.

Tacrolimus and ciclosporine? Limited data. Some moms breastfeed under close supervision. But your doctor needs to check your drug levels and your baby’s health regularly.

There’s no one-size-fits-all answer. But there is a rule: if you’re unsure, don’t breastfeed until you’ve talked to your transplant team and a pediatrician who understands immunosuppressants.

What’s Missing? What’s Next?

We’ve come a long way since 2000, when doctors had almost no data on children born to parents on these drugs. Now, 85% of transplant centers have formal pregnancy protocols.

But gaps remain. We don’t know the long-term effects on immune development in kids exposed in utero. We don’t have enough data on newer drugs like belatacept or voclosporin. And we still don’t track paternal exposure systematically.

The future? Registries. More studies. Better guidelines. But right now, your best tool is information-and a team that listens.

Don’t wait until you’re pregnant to ask questions. Don’t assume your rheumatologist knows the fertility risks. Don’t trust a Google search. Go to a specialist. Find a clinic that handles both autoimmune disease and fertility. Ask for a joint consult with a reproductive endocrinologist and your transplant team.

This isn’t about being scared. It’s about being prepared.

What to Do Next

If you’re on immunosuppressants and thinking about having a child:

1. Make an appointment with your rheumatologist or transplant specialist and a reproductive endocrinologist-ideally together.
2. Get a full fertility assessment: ovarian reserve tests for women, semen analysis for men.
3. Review every medication you’re taking. Ask: Is this the safest option for pregnancy?
4. If you’re on cyclophosphamide or methotrexate, discuss fertility preservation immediately.
5. Plan at least six months ahead. Don’t rush. Your body needs time to adjust.
6. Keep track of your lab values: creatinine, blood pressure, immune markers. Stability matters.

This isn’t about giving up your health to have a baby. It’s about protecting both. The right plan turns a high-risk situation into a manageable one. And with the right team, many people go on to have healthy children-on the right drugs, at the right time.