A lactating mother two weeks postpartum wants hormonal contraception. Her physician prescribes a progestin-only pill rather than a combined pill. The primary contraceptive mechanism of the progestin-only pill taken in conventional continuous dosing is:

• A Suppression of the midcycle LH surge with consistent anovulation
• B Induction of atrophic changes in the endometrium preventing implantation
• C Thickening of cervical mucus making sperm penetration difficult ✓
• D Direct inhibition of spermatogenesis via androgen receptor agonism

Explanation

At conventional doses, older progestin-only pills do not reliably suppress ovulation; their main effect is viscous cervical mucus that blocks sperm transport. They are preferred in lactation because they do not reduce milk volume, unlike the estrogen component of combined pills. Suppression of the LH surge is the hallmark of combined pills and of desogestrel-only pills, not classic norethisterone or levonorgestrel POPs.

Reference: Williams Gynecology, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.