Do any of my medications need to change before I start trying?

A medication review is one of the few genuinely high-value things you can do before you start trying, and it is routinely skipped. Some prescriptions need swapping months ahead. Some need stopping. And a surprising number of the ones people assume they should stop are the ones they should stay on.

Where to start

Book a preconception visit and bring everything: prescriptions, over-the-counter medicines, supplements and doses. Ask the direct question: is there anything here that should change before I start trying, and how far ahead?

That timing question is the one that gets missed. For most medications the answer is "we can switch you whenever." For a handful it's "months."

The ones that need the longest lead time

Two of these apply to men too: the rheumatology guideline asks men to stop cyclophosphamide 12 weeks and thalidomide 4 weeks before trying to conceive.

Strong evidence The ones usually switched, and why

• ACE inhibitors and ARBs (lisinopril, losartan and similar) are linked to fetal kidney abnormalities and fetal death. There are blood pressure medications with a long pregnancy track record to move to instead.
• Warfarin is teratogenic. Heparin and low-molecular-weight heparin don't cross the placenta, which is why they're the pregnancy substitute.
• Most oral diabetes medications are switched, usually to insulin. Metformin is often continued — it's the common exception, and worth asking about specifically rather than assuming.
• Methimazole for an overactive thyroid is generally avoided in the first trimester, with propylthiouracil preferred early on.
• Seizure medications — valproate above all, and also phenytoin, carbamazepine and phenobarbital — carry real risks, and the aim is one medication at the lowest effective dose, settled before pregnancy. Never adjust these yourself. An uncontrolled seizure is more dangerous than almost any alternative.
• Statins. In 2021 the FDA asked manufacturers to drop the blanket contraindication, while still advising that most people stop once pregnant. For someone at very high cardiovascular risk it is now a conversation rather than an automatic stop.

Strong evidence The ones usually continued

This half of the list is the one people never hear, and stopping these can do real harm.

• Hydroxychloroquine is not only continued in lupus and related conditions — it's actively recommended, and in some situations it protects the baby.
• Colchicine, azathioprine and TNF inhibitors are generally continued.
• Asthma inhalers and controller medication. An asthma attack is a far bigger threat to a pregnancy than the inhaler.
• Levothyroxine continues, and the dose almost always needs to rise early in pregnancy. What the thyroid numbers mean.

Strong evidence Antidepressants and mental health medication

ACOG's 2023 guideline is unusually direct here: medication for a mental health condition should not be withheld or stopped because of pregnancy alone, and discontinuing treatment that is working raises the risk of relapse.

The numbers behind that are striking. In one study of women with mood disorders, 68% of those who stopped their medication relapsed, against 26% of those who stayed on — a fivefold difference in risk.

None of which means every medication is the right one to carry into pregnancy. It means the decision is a weighing-up with your prescriber, where the risk of becoming unwell is counted properly on the other side of the scale.

Limited or mixed Everyday painkillers, around ovulation

Anti-inflammatory painkillers — ibuprofen, naproxen, aspirin at pain doses — interfere with the prostaglandins that help a follicle rupture and release an egg. A small controlled study found ovulation was delayed in 85% of cycles on ibuprofen, against 20% without it.

The studies are small, so we're rating this limited. The practical version: if you need regular pain relief in the week around ovulation, ask whether paracetamol (acetaminophen) would do instead. This is not a reason to suffer through pain, and it says nothing about low-dose aspirin, which is a different dose for a different purpose. Who qualifies for low-dose aspirin.

GLP-1 medications: the longest planning problem

Semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound), liraglutide and the rest of this class are common enough that "what do I do about this before I try" has become one of the most-asked and least-answered questions in fertility communities. It gets the most space here because it needs the most lead time.

Why unexpected pregnancies happen on these drugs

Strong evidence Weight loss can restore ovulation. In people with obesity or PCOS whose cycles had stopped or become irregular, losing weight often brings ovulation back. Someone who assumed she couldn't easily conceive may suddenly be able to. This is the main mechanism behind what the internet calls "Ozempic babies," and it's a well-established effect of weight loss generally, not something unique to these drugs.

Strong evidence Tirzepatide can make the pill less effective. Tirzepatide delays gastric emptying, which slows absorption of oral medication, including oral contraceptives. The manufacturer advises switching to a non-oral method or adding a barrier method for 4 weeks after starting, and for 4 weeks after every dose increase. Non-oral hormonal methods (patch, injection, implant, IUD) aren't affected. This is a specific, actionable interaction that a lot of people are never told about.

Emerging evidence Possible direct reproductive effects. GLP-1 receptors appear in reproductive tissue, and there's active research into whether these drugs affect ovarian function and egg quality beyond what weight loss alone explains. Interesting, unresolved, and not a reason to take or avoid them today.

If you're planning to conceive

Strong evidence These medications are not recommended in pregnancy, and the label says to stop well in advance. The Wegovy prescribing information instructs discontinuing "at least 2 months before a planned pregnancy," because semaglutide has a long half-life and remains detectable for roughly 5 to 7 weeks after the last full dose. Other drugs in the class have different half-lives and different guidance, so this is a question for your prescriber rather than a number to copy from a forum.

The practical consequence is that this needs planning. Two months off the medication before you even start trying, plus however long trying takes, is a real stretch of time, and weight regain during it is common. That trade-off deserves a proper conversation with whoever prescribes it and whoever is managing your fertility care, ideally together.

Safety consideration Don't stop abruptly on your own if you have diabetes. If the medication is treating diabetes rather than weight, stopping changes your blood sugar management and needs a plan. Uncontrolled diabetes carries its own significant pregnancy risks.

If you conceived while taking one

First: this happens, it is not your fault, and the evidence so far is broadly reassuring.

Strong evidence Stop the medication and tell your doctor. The labeling instructs discontinuing when pregnancy is recognized.

Limited or mixed Inadvertent exposure has not been clearly linked to birth defects. A systematic review and meta-analysis of seven cohort studies covering more than 40,000 exposed pregnancies found no statistically significant increase in overall congenital anomalies (odds ratio 1.11, confidence interval 0.82–1.51), and first-trimester exposure specifically was also not significant (1.39, 0.73–2.65). Two studies showed a signal for urinary malformations (1.24, 1.05–1.47), but those estimates were unadjusted and may reflect maternal diabetes or obesity rather than the drug. The authors graded the evidence quality as low to very low.

We're labeling that limited rather than strong on purpose. It's cautious reassurance for someone who conceived unexpectedly, which is genuinely how it should be read. It is not evidence that these drugs are safe to use during pregnancy, and the researchers say so themselves.

Limited or mixed The preterm birth question. A Danish nationwide cohort of 756,636 pregnancies, including 529 with periconceptional GLP-1 exposure, found higher preterm birth rates in exposed pregnancies overall. But when split by why the drug was prescribed, the increase appeared only in people taking it for diabetes, not for weight management alone, which points at the underlying diabetes rather than the medication. A good example of why "exposed versus unexposed" headlines are often really about who takes the drug.

If you're heading into fertility treatment

Many clinics ask patients to stop GLP-1 medications before starting a cycle, both because of the pregnancy labeling and because of sedation considerations at egg retrieval, since delayed gastric emptying is relevant to anesthesia. Timelines vary by clinic and by drug. Ask early rather than the week before, because the answer may add a month or two to your plan.

What to ask your doctor

• Looking at everything I take, is there anything that should change before I start trying — and how far ahead?
• Is there anything on this list I should not stop, even though I might assume I should?
• If something needs switching, what's the alternative, and how long does the changeover take?
• Could any of these make my contraception less reliable in the meantime?
• If I'm on a GLP-1 medication: how long before trying should I stop, and what's the plan for my weight or blood sugar during that gap?
• If I'm doing IVF, when do you want me off it, and does it affect the retrieval?

The honest summary

Two mistakes are common here, and they pull in opposite directions. One is carrying on with a medication that needed swapping months ago, because nobody asked. The other is stopping something abruptly — an antidepressant, an inhaler, a seizure medication — out of fear, and becoming unwell at the worst possible time.

Both are avoided by the same thing: a conversation, early, with the list in your hand.