Pregnancy, contraception and the two-month rule

This is the part of the labelling with the least ambiguity in it and the least presence in the marketing. Everything below is quoted from the current prescribing information for the two leading products.

The contraceptive interaction is real, and it is drug-specific

Lilly instructs that patients using oral hormonal contraceptives “switch to a non-oral contraceptive method, or add a barrier method of contraception for 4 weeks after initiation with ZEPBOUND and for 4 weeks after each dose escalation.” The reason is the same delayed gastric emptying that causes the nausea: a single 5 mg dose cut peak ethinyl estradiol concentration by 59%, norgestimate by 66% and norelgestromin by 55%.

Two things about that instruction are easy to miss. It applies again at every dose increase, not only at the start — which on the standard ladder means five or six separate four-week windows across the first year. And it applies to oral hormonal contraception specifically; the label says non-oral hormonal methods “should not be affected.”

Novo’s label sets out no comparable warning for semaglutide. In the interaction studies run for Wegovy tablets, ethinyl estradiol and levonorgestrel were among the drugs showing no clinically significant pharmacokinetic change. The two molecules are not interchangeable on this point, which is a specific instance of the broader argument in Semaglutide vs tirzepatide and the full interaction picture in What else you are taking, and why these drugs change it.

If you are trying to conceive

Novo’s instruction is a washout with a number attached: “Because of the potential for fetal harm, discontinue WEGOVY® in patients at least 2 months before they plan to become pregnant to account for the long half-life of semaglutide.” Two months is not caution for its own sake — it is the time the molecule takes to clear.

That has a consequence the pricing conversation never covers. Anyone planning a pregnancy has to stop roughly eight weeks ahead, and stopping is not a neutral event in this class: the withdrawal and extension data in What happens when you stop is consistent that weight is substantially regained. Planning a pregnancy on one of these drugs means planning that too.

The registries exist because the data does not

Both manufacturers run a pregnancy exposure registry and ask that exposed pregnancies be reported — Novo at 1-877-390-2760, Lilly at 1-800-545-5979. Lilly’s label describes its registry in the future tense, which is itself informative about how new this evidence base is. If you become pregnant on one of these drugs, reporting it is how the next set of patients gets better information than you had.

What the services do and do not tell you

Pregnancy screening is not something this site can verify from the outside — what an intake asks is visible only once you are inside it. What can be counted is how much a service publishes at all: 78 of the 87 reviewed here describe who they will and will not treat, and 13 mention bloodwork of any kind. An intake that does not ask about pregnancy, pregnancy plans or contraception has skipped the clearest instruction in the labelling — see Who qualifies for a GLP-1, and what a real intake asks and Thirteen things a GLP-1 service should tell you before you pay.

And a compounded product carries none of this labelling, because it has no approved label. Every instruction on this page describes the branded products — Brand-name vs compounded GLP-1s.