Pregnancy testing on GLP-1 therapy: what the labels say about pregnancy, contraception and the washout

A pregnancy test is the one item on this site that is not about monitoring therapy. It is about whether therapy should be happening at all. The labels are consistent: these drugs may cause fetal harm, weight loss is not recommended in pregnancy, and the drug should be stopped when a pregnancy is recognized. Whether that translates into a test before the first dose is left to the prescriber, and most choose to.

The test

Pregnancy tests detect human chorionic gonadotropin (hCG), a hormone produced once an embryo implants. A qualitative test (urine, or a blood test that reports positive or negative) answers yes or no. A quantitative blood test reports a number: MedlinePlus lists under 5 mIU/mL as the normal level in non-pregnant women, with levels rising rapidly through the first trimester. For the purpose of a pre-treatment check the qualitative test is enough; a quantitative test is used to date or follow a pregnancy, not to screen for one.

Timing matters. A test taken before a missed period can be negative in an early pregnancy. If the last cycle was irregular or contraception was inconsistent, a repeat test a week or two later answers the question more reliably than a single early one.

What the labels say

Fetal harm. The Wegovy label's pregnancy section states that weight loss offers no benefit to a pregnant patient and may cause fetal harm, and that when a pregnancy is recognized the patient should be advised of the risk and the drug discontinued. The Zepbound label says the same in its own words: discontinue when pregnancy is recognized.

The semaglutide washout. Wegovy and Ozempic, section 8.3: discontinue at least 2 months before a planned pregnancy because of the long half-life of semaglutide. Two months is roughly five half-lives, the point at which most of the drug has cleared. The tirzepatide labels do not state a specific washout period; they say to discontinue when pregnancy is recognized. If you are planning a pregnancy on tirzepatide, that is a conversation to have in advance rather than a rule to look up.

Tirzepatide and oral contraceptives. Zepbound and Mounjaro, sections 7.2 and 8.3: tirzepatide may reduce the efficacy of oral hormonal contraceptives because of delayed gastric emptying; the effect is largest after the first dose and diminishes over time; advise switching to a non-oral method or adding a barrier method for 4 weeks after initiation and for 4 weeks after each dose escalation; non-oral hormonal contraceptives should not be affected. The semaglutide labels do not carry this instruction.

Registries. The Wegovy and Zepbound labels describe pregnancy exposure registries that monitor outcomes in women exposed during pregnancy, and encourage patients and clinicians to enrol. If a pregnancy happens on therapy, the registry is how the data that future labels rely on gets collected.

Why prescribers test anyway

Put those label statements together and the case for a baseline test writes itself. The drug is one you would stop the day you learned of a pregnancy; a test before the first dose costs little and removes the scenario where the first weeks of an unknown pregnancy overlap with the first weeks of therapy. Some prescribers repeat the test at dose escalations, especially on tirzepatide because of the contraceptive interaction. Neither practice is a label requirement; both are consistent with the label's intent.

How often

• Before the first dose: commonly, at the prescriber's discretion. Not label-mandated.
• At dose escalations: some prescribers, particularly on tirzepatide for people using oral contraception. Ask what your prescriber's practice is.
• If a period is missed or contraception failed: immediately, and stop the drug if positive until you have spoken to your prescriber.
• Planning a pregnancy: the test is the least of it. The semaglutide washout and the whole plan for weight, glucose and nutrition in pregnancy come first.

What to discuss with your prescriber

• Your contraception, and whether it is oral (relevant on tirzepatide) or not.
• Whether a pregnancy test is wanted before the first dose and at escalations.
• If you plan to conceive within the year: the washout period and what happens to weight management during the gap.
• Breastfeeding, which has its own section (8.2) in each label and is not covered on this page.

The FormBlends Guides site has a longer piece on pregnancy planning around GLP-1 therapy. Compounded semaglutide and tirzepatide are not FDA approved and carry no FDA-reviewed pregnancy section; the statements above come from the brand labels and are the minimum a compounded product should be held to.