Will taking 200mg of micronized progesterone from day 5 to day 28 of the menstrual cycle suppress ovulation?

Micronized Progesterone 200mg from Day 5-28 Will Suppress Ovulation

Yes, taking micronized progesterone 200mg daily from day 5 through day 28 of the menstrual cycle will suppress ovulation. This regimen provides continuous progesterone exposure during the follicular phase, which inhibits the midcycle gonadotropin surge necessary for ovulation.

Mechanism of Action

Progesterone plays a critical role in regulating the menstrual cycle and ovulation:

• Progesterone administration during the follicular phase (when started on day 5) prevents the estrogen-primed LH surge that triggers ovulation 1
• Continuous progesterone exposure disrupts the normal hypothalamic-pituitary-ovarian axis signaling required for follicular development and ovulation
• The dose of 200mg is sufficient to achieve therapeutic serum levels that can alter endometrial development and hormonal feedback loops 2, 3

Evidence Supporting Ovulation Suppression

Research demonstrates that progesterone is essential for triggering the LH surge when present at the right time in the cycle, but continuous administration from early in the cycle prevents this process:

• Studies using the antiprogesterone RU 486 showed that blocking progesterone action delayed the midcycle gonadotropin surge despite rising estradiol levels, confirming progesterone's critical role in ovulation timing 1
• Seven days of continuous hormonal contraceptive use is deemed necessary to reliably prevent ovulation according to CDC guidelines 4
• Starting progesterone on day 5 (early follicular phase) and continuing through day 28 provides more than the minimum duration needed for ovulation suppression

Dosage Considerations

The 200mg daily dose of micronized progesterone is clinically significant:

• This dose is sufficient to produce adequate plasma and tissue levels of progesterone 2
• It reproduces the anti-estrogenic effect of natural progesterone on the endometrium 2
• Oral micronized progesterone at 200mg has been established as an effective dose for endometrial protection in hormone therapy regimens 3

Clinical Applications

This regimen is similar to approaches used in various clinical scenarios:

• In hormone replacement therapy, 200mg of micronized progesterone is commonly used for 12-14 days per cycle or continuously 4
• For contraception, continuous progestogen exposure is a key mechanism for preventing ovulation 4
• In premature ovarian insufficiency management, similar progesterone dosing is used alongside estrogen therapy 4

Important Considerations

When using this regimen, be aware of:

• Potential side effects including fluid retention, dizziness, and drowsiness 5
• Micronized progesterone contains peanut oil and should not be used in patients with peanut allergies 5
• Continuous progesterone administration may contribute to depressive symptoms in some women 6
• Taking the dose at bedtime can minimize drowsiness side effects 3

This progesterone regimen starting on day 5 provides early and continuous exposure throughout the follicular phase, effectively preventing the hormonal cascade required for ovulation, making it an effective approach for ovulation suppression.