GLP-1 medication, pregnancy, contraception, and fertility

This article is specifically for women of reproductive age. GLP-1 medications interact with pregnancy and contraception in ways that matter. If any of these apply to you, please read carefully.

Do not use GLP-1 medication in pregnancy

Semaglutide and tirzepatide are both classified as not recommended during pregnancy. The evidence base is limited; animal studies have shown adverse effects on the foetus and there is no adequate human data to overturn that signal.

Our rules:

We do not prescribe in women who are currently pregnant.

We do not prescribe in women who are planning pregnancy within the next 2-3 months.

We recommend stopping GLP-1 medication at least 2 months before trying to conceive.

If you become pregnant while on treatment, stop the medication immediately and book a GP or obstetrician review.

Fertility while on GLP-1 medication

There is a phenomenon you may have seen in the news. Weight loss on GLP-1 medication can restore fertility in women whose fertility was reduced by obesity. This sometimes leads to unplanned pregnancy.

Why this happens:

Obesity suppresses ovulation in many women (through altered insulin signalling, inflammation, and hormonal disruption).

Modest weight loss (5-10 percent of body weight) often restores regular ovulation.

Women who had previously not ovulated reliably can start ovulating within 2-3 months of starting effective GLP-1 treatment.

If you are on treatment and sexually active, you need effective contraception. The weight loss itself, regardless of anything else, changes your reproductive biology.

Contraception and oral absorption

This is the important part.

Oral contraceptives (combined pill, progesterone-only pill): GLP-1 medications slow gastric emptying, which can delay and reduce absorption of oral medications. The combined pill has been specifically studied with semaglutide and showed small reductions in absorption that were not large enough to affect pregnancy prevention in most cases.

However, the manufacturer's precaution (and our recommendation) is that during the first 4 weeks after starting or escalating GLP-1 dose, you should use a second method of contraception (condom, vaginal ring in addition to pill) because absorption may be more erratic during that period.

Reliable alternatives: any non-oral contraceptive method is unaffected:

Hormonal coil (Mirena, Jaydess, Kyleena, Levosert).

Copper coil.

Implant (Nexplanon).

Depot injection (Depo-Provera).

Hormonal patch or vaginal ring (absorption is not affected because these are not oral).

If you are on the pill and planning GLP-1 treatment, we will discuss whether to switch to a more reliable method or use dual contraception.

Breastfeeding

GLP-1 medications are also contraindicated while breastfeeding. There is limited data on transfer into breast milk, and the manufacturer advises against use.

Our rule: we do not prescribe during breastfeeding. If you have been on treatment and become pregnant, we stop the medication. After delivery, we do not restart while you are breastfeeding.

When to restart: we can restart GLP-1 medication approximately 2-3 months after weaning, or earlier if your obstetrician agrees.

Planning pregnancy intentionally

If you have completed a course of GLP-1 treatment and want to try for a pregnancy:

Stop the medication 2 months before attempting conception.

Do not worry about short-term "wash-out" concerns. The medication is largely cleared from your body within 4-5 weeks.

Consider that your fertility may be higher than before treatment, so planning pregnancy is straightforward; conception may happen quickly.

Your weight loss pre-conception is likely to improve pregnancy outcomes: reduced rate of gestational diabetes, reduced rate of pre-eclampsia, easier delivery.

If you have struggled with fertility specifically due to polycystic ovary syndrome (PCOS), GLP-1 medication has a strong evidence base for restoring ovulation in this specific group.

What to do if you suspect you are pregnant on treatment

If your period is late and you might be pregnant:

Take a home pregnancy test.

If positive, stop the medication immediately.

Book a GP or obstetrician review within a week.

Continue routine folic acid and vitamin D if not already on them.

The outcome is usually fine. The theoretical concerns about GLP-1 in pregnancy are based on limited data. Several women who became pregnant unexpectedly on GLP-1 medication in clinical trials went on to have healthy babies. The precaution is real, but occasional exposure in the first few weeks is not automatically a high-risk pregnancy.

However, this does not make it acceptable to continue the medication during pregnancy. The precaution is a precaution.

Polycystic ovary syndrome (PCOS)

Specific note because this is a common clinical scenario.

Many women with PCOS struggle with:

Irregular periods or absent ovulation.

Insulin resistance and weight gain.

Fertility issues, often as the presenting concern.

GLP-1 medication addresses several of these simultaneously. Weight loss improves insulin resistance, restores ovulation, reduces androgens, and often results in regular periods.

For women with PCOS trying to conceive, the usual approach is:

Use GLP-1 medication for 6-12 months to achieve weight loss and restored ovulation.

Stop the medication.

Try to conceive in the subsequent 6-12 months, using the now-better metabolic state.

Restart the medication after pregnancy and breastfeeding if weight has regained.

We see good outcomes from this approach in appropriately-selected PCOS patients.

What to discuss in your first consultation

If you are of reproductive age, we specifically ask about:

Current contraception.

Plans for pregnancy.

Previous pregnancies and any complications.

Menstrual regularity.

Any fertility concerns.

This conversation determines whether we prescribe, what contraceptive backup we recommend, and what the exit plan looks like if pregnancy is planned in the next year.

The honest summary

GLP-1 medication is effective and safe for many women of reproductive age, but requires awareness of contraception, fertility restoration, and the clear stop if pregnancy is planned or occurs. We walk through these specifics in your first consultation.

Ready to start?

If this article has made you think medication might help, the next step is a short consultation with one of our weight-management doctors.

Begin your assessment at this link. Online in 30 minutes, or in person at Westfield London.