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Tirzepatide, the birth control pill and unplanned pregnancies

  • MDside
  • October 9, 2026

Key points

  • A 5 mg dose of tirzepatide reduced ethinyl estradiol Cmax by 59% and AUC by 20% [1].
  • The label says to switch to a non-oral method or add a barrier method for 4 weeks after starting and after each dose increase [1]. The UK’s MHRA repeated this in 2025 [2].
  • With first-trimester exposure, major malformations were not clearly increased (aRR 0.95 vs insulin), and the intervals are wide [4][5].
  • The Wegovy label says to stop at least 2 months before a planned pregnancy [3].

US status (October 2026): Tirzepatide is FDA-approved as Mounjaro and Zepbound, and the shortage was resolved on December 19, 2024. Tirzepatide status page.

Two effects add up to more pregnancies

The first is pharmacokinetic. On the tirzepatide label, a single 5 mg dose reduced the Cmax of ethinyl estradiol, norgestimate and norelgestromin by 59%, 66% and 55%, and AUC by 20%, 21% and 23%, with Tmax delayed by 2.5 to 4.5 hours [1]. According to the label, the mechanism is delayed gastric emptying, and the effect is largest after the first dose and diminishes over time [1].

The second is reproductive. GLP-1s may improve ovulatory function and menstrual regularity, particularly in women with obesity or polycystic ovary syndrome [8]. In a randomized pilot trial in infertile women with obesity and polycystic ovary syndrome (28 participants), the pregnancy rate per embryo transfer was 85.7% with liraglutide plus metformin vs 28.6% with metformin alone, despite similar weight loss in both groups [7]. A 2026 review discusses concerns about unintended pregnancies due to improved fertility [8].

  • 59% lower: ethinyl estradiol Cmax after 5 mg tirzepatide [1]
  • 4 weeks: of backup contraception after starting and each dose increase [1]
  • 2 months: Wegovy washout before a planned pregnancy [3]

The label and regulators say the same thing

The Zepbound label advises oral-contraceptive users to “switch to a non-oral contraceptive method, or add a barrier method of contraception for 4 weeks after initiation … and for 4 weeks after each dose escalation” [1]. In June 2025 the UK’s MHRA advised that overweight Mounjaro users taking oral contraception should also use a non-oral method [2]. The Wegovy label says to stop it at least 2 months before a planned pregnancy [3].

For your weight management program, that means a contraception question at intake and again at every dose escalation, documented in the chart.

Pregnancy exposure data show no large signal and cannot rule one out

  • Nordic, US and Israeli cohort of women with type 2 diabetes (JAMA Intern Med 2024): major congenital malformations 8.3% with GLP-1s (938 pregnancies), aRR 0.95 (0.72 to 1.26) vs insulin [4].
  • Target-trial emulation with 3,572 pregnancies (Ann Intern Med 2026), continuing vs stopping the GLP-1 in the first trimester: major malformations PR 1.21 (0.83 to 1.82). The authors conclude the estimates are compatible with both no increased risk and clinically relevant differences [5].
  • Denmark (2026): preterm birth was raised only in users with diabetes (aOR 1.84 with semaglutide), not in weight-management users (aOR 0.71; 0.30 to 1.70), which the authors say is compatible with the underlying diabetes, rather than the drug, being the cause [6].

What happened in Panama, and why US clinics should care

Panama’s health ministry (MINSA) and the Pan American Health Organization have issued alerts describing GLP-1 sales through social media and unofficial channels, outside the doctor’s office [9][10]. In that channel no one explains the interaction with oral contraceptives [1]. A patient who started on a product bought online can arrive at your clinic without that counseling, so ask. The US compounding picture is in compounded GLP-1s after the shortage.

What this means for you

  1. Ask every patient of reproductive potential about contraception at intake, and record the method.
  2. For oral contraceptive users on tirzepatide, give the label instruction in writing: switch to a non-oral method, or add a barrier method for 4 weeks after starting and for 4 weeks after each dose escalation [1].
  3. Repeat the question at every dose change. The label ties backup contraception to every escalation, which is when it is easiest to forget [1].
  4. For patients planning a pregnancy, follow the product label on stopping. The Wegovy label sets at least 2 months [3].
  5. If a patient becomes pregnant on a GLP-1, the cohort data above are reassuring and imprecise [4][5]. Document the exposure and coordinate with the patient’s obstetric care.

References

  1. Eli Lilly and Company. Zepbound (tirzepatide) US prescribing information, revised 08/2026. Link
  2. Medicines and Healthcare products Regulatory Agency (UK). Women on ‘skinny jabs’ must use effective contraception, MHRA urges in latest guidance. 5 June 2025. Link
  3. Novo Nordisk. Wegovy (semaglutide) US prescribing information, revised 06/2026. Link
  4. Cesta CE, et al. Safety of GLP-1 receptor agonists and other second-line antidiabetics in early pregnancy. JAMA Intern Med. 2024;184(2):144-152. PMID 38079178. Link
  5. Brown JP, et al. Continuing Glucagon-Like Peptide-1 Receptor Agonists Into the First Trimester of Pregnancy and Pregnancy Outcomes : A Target Trial Emulation Study Using Claims Information. Ann Intern Med. 2026;179(7):929-937. PMID 42258827. Link
  6. Hviid KVR, et al. Periconceptional GLP-1 receptor agonist exposure and obstetric outcomes: a Danish nationwide cohort study. Hum Reprod Open. 2026;2026(2):hoag015. PMID 41852577. Link
  7. Salamun V, et al. Liraglutide increases IVF pregnancy rates in obese PCOS women with poor response to first-line reproductive treatments: a pilot randomized study. Eur J Endocrinol. 2018;179(1):1-11. PMID 29703793. Link
  8. Abedi MM, et al. GLP-1 Receptor Agonists, Fertility Restoration, and Reproductive Safety in Women of Reproductive Age: A Narrative Review. J Clin Med. 2026;15(9):3204. PMID 42122936. Link
  9. Ministerio de Salud de Panamá, DNFD. Comunicado 050/DNFD-2024: Alerta sobre el producto Semaglutida + Vitamina B12. 2 de mayo de 2024. Link
  10. Organización Panamericana de la Salud. Ante reportes de uso indebido de medicamentos GLP-1 indicados para tratar la obesidad, la OPS pide reforzar la farmacovigilancia. 3 de marzo de 2026. Link

This is general information, not medical or legal advice. Rules vary by state and change. Confirm your own facts with counsel.

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Medical direction. Victor D. Cruz, MD, Systems Medical Director, licensed in Florida (ME117105) and New York, directs structure, corporate practice of medicine, delegation and good faith exams. This states who carries clinical responsibility for this subject area. It is not a page-level review: pages that have been reviewed name the reviewer and show the date. How this site is written and checked.