Can Lupin (combined oral contraceptive (COC) or progestin-only pill (POP)) birth control reduce the size of uterine fibroids and endometrial thickness in a female patient of reproductive age with uterine fibroids or endometrial hyperplasia?

Lupin Birth Control and Uterine Fibroids/Endometrial Thickness

Combined oral contraceptives (COCs) and progestin-only pills (POPs) do not reduce fibroid size, but COCs can effectively reduce heavy menstrual bleeding associated with fibroids; neither COCs nor POPs are designed to shrink fibroids or reduce endometrial thickness as a primary therapeutic goal. 1, 2

Effect on Uterine Fibroids

Fibroid Size Reduction

• Progestin-only contraceptives (including POPs) do not cause growth or shrinkage of uterine fibroids 1
• COCs are less effective than levonorgestrel-releasing intrauterine systems (LNG-IUS) in reducing fibroid volume 3
• One low-quality study suggested COCs may be more effective than placebo for tumor size reduction, but this evidence is very scarce and uncertain 3
• For actual fibroid volume reduction, selective progesterone receptor modulators (SPRMs) like ulipristal acetate achieve 30% reduction after one course and up to 70% after four courses—far superior to any hormonal contraceptive 1

Bleeding Control

• COCs with step-down estrogen and step-up progestogen regimens significantly reduce menstrual blood loss in women with fibroids, increasing treatment success from 3% (placebo) to 12-77% 4
• The American College of Radiology recommends estrogen-progestin oral contraceptive pills as first-line medical management for reducing bleeding symptoms associated with uterine fibroids 2
• However, the LNG-IUS is more effective than COCs for controlling heavy menstrual bleeding in women with fibroids 4, 3

Effect on Endometrial Thickness

Endometrial Changes with Hormonal Contraceptives

• COCs induce regular shedding of a thinner endometrium, which is their mechanism for reducing menstrual blood loss 4
• Progestin-only pills can cause irregular bleeding patterns but do not predictably reduce endometrial thickness 1
• For endometrial hyperplasia specifically, both POPs and COCs are rated as Category 1 (no restriction) by the U.S. Medical Eligibility Criteria, meaning they are safe but not specifically therapeutic 1

Comparison to Other Agents

• Selective progesterone receptor modulators (SPRMs) like ulipristal acetate cause unique endometrial changes called PAEC (progesterone receptor modulator-associated endometrial changes), with mean endometrial thickness of 8mm at end of first treatment course—similar to placebo 1
• GnRH antagonists (elagolix, linzagolix, relugolix) are second-line treatments that significantly reduce both bleeding symptoms and fibroid volume, far more effective than COCs for fibroid management 2

Clinical Algorithm for Treatment Selection

For Heavy Menstrual Bleeding as Primary Symptom:

1. Start with COCs or LNG-IUS as first-line options (LNG-IUS preferred if contraception also desired) 2, 4
2. Add NSAIDs or tranexamic acid for additional bleeding control 2
3. Progress to GnRH antagonists with hormone add-back therapy if inadequate response 2

For Fibroid Volume Reduction:

1. Do not use COCs or POPs—they are ineffective for this goal 1, 3
2. Use GnRH agonists or antagonists for most effective volume reduction 2
3. Consider SPRMs (ulipristal acetate where available) for 30-70% volume reduction 1

For Endometrial Hyperplasia:

1. COCs and POPs are safe to use but not specifically therapeutic 1
2. Progestin therapy (not POP doses) is the standard treatment for endometrial hyperplasia
3. Endometrial biopsy is mandatory before initiating treatment to exclude malignancy 5

Critical Pitfalls to Avoid

• Do not prescribe COCs or POPs expecting fibroid shrinkage—this is not their mechanism of action and evidence shows minimal to no effect on tumor size 1, 3
• Do not confuse bleeding control with fibroid reduction—COCs reduce menstrual blood loss through endometrial thinning, not fibroid shrinkage 4
• Contraceptive efficacy is maintained with POPs despite irregular bleeding patterns, but patients must be counseled about this common side effect 1
• Most medical treatments provide only temporary symptom relief with recurrence after discontinuation—this applies to all hormonal contraceptives 2
• The evidence for COCs in fibroid management is low quality, based on small trials with high risk of bias 3

Special Populations

Women Desiring Future Fertility:

• COCs and POPs are appropriate for symptom management while preserving fertility 2
• Submucosal and intramural fibroids significantly impair implantation rates (pregnancy rate 16.4% vs 30.1% in controls), so fibroid reduction may be necessary before conception attempts 1
• Subserosal fibroids do not affect pregnancy rates (34.1% vs 30.1% controls) and do not require treatment before fertility attempts 1

Perimenopausal Women:

• COCs can help transition to menopause while avoiding surgery for fibroid symptoms 1
• Pulsatile courses of SPRMs (where available) are especially useful in this population 1