Why would a person experience heavy bleeding after initiating progesterone Oral Contraceptive Pills (OCP) when they had previously experienced amenorrhea (absence of menstruation) for one year?

From the Guidelines

Heavy bleeding after initiating progesterone Oral Contraceptive Pills (OCPs) in someone who had previously experienced amenorrhea for one year is likely due to hormonal withdrawal bleeding, and the bleeding should normalize after 2-3 cycles as the hormones regulate the endometrial growth. This condition can be managed by exploring patient goals, including continued method use or method discontinuation, and providing reassurance and advice on managing bleeding irregularities 1. According to the 2024 U.S. Selected Practice Recommendations for Contraceptive Use, if the patient wants treatment, options such as NSAIDs, hormonal treatment, or antifibrinolytic agents may be considered, depending on the patient’s preferences, treatment goals, and medical history 1.

Key Considerations

• The introduction of progesterone in OCPs can cause the accumulated endometrium to shed, resulting in heavier-than-normal bleeding when the hormone levels drop during the pill-free week.
• This condition is especially common in individuals with a history of irregular or absent periods, such as those with polycystic ovary syndrome (PCOS), hypothalamic amenorrhea, or perimenopause.
• If the heavy bleeding persists beyond 3 months, becomes extremely heavy, or causes significant anemia, medical evaluation is necessary to rule out underlying health conditions, such as interactions with other medications, sexually transmitted infections, pregnancy, thyroid disorders, or new pathologic uterine conditions 1.

Management Options

• Switching to a different OCP formulation
• Continuous pill use without breaks
• Adding supplemental estrogen temporarily
• NSAIDs, 5–7 days
• Hormonal treatment (e.g., low dose COCs or estrogen), 10–20 days
• Antifibrinolytic agents (e.g., tranexamic acid), 5 days It is essential to consider the patient's preferences, treatment goals, and medical history when selecting a management option, and to provide counseling on alternative contraceptive methods if the patient desires removal or discontinuation of the method 1.

From the FDA Drug Label

PATIENT INFORMATION Progesterone Capsules, 100 mg and 200 mg Rx only Read this PATIENT INFORMATION before you start taking progesterone capsules and read what you get each time you refill your progesterone capsules prescription. What is progesterone capsules used for? Treatment of Menstrual Irregularities Progesterone capsules are used for the treatment of secondary amenorrhea (absence of menstrual periods in women who have previously had a menstrual period) due to a decrease in progesterone When you do not produce enough progesterone, menstrual irregularities can occur. If your healthcare provider has determined your body does not produce enough progesterone on its own, progesterone capsules may be prescribed to provide the progesterone you need

The person may experience heavy bleeding after initiating progesterone Oral Contraceptive Pills (OCP) because their body is readjusting to the presence of progesterone after a year of amenorrhea.

• The progesterone in the OCPs can cause the uterine lining to shed, leading to bleeding.
• This is a common side effect of hormonal therapy, especially in women who have not had a menstrual period in a long time.
• The bleeding may be heavy due to the sudden change in hormone levels. 2

From the Research

Heavy Bleeding after Initiating Progesterone OCP

• The provided studies do not directly address why a person would experience heavy bleeding after initiating progesterone Oral Contraceptive Pills (OCP) when they had previously experienced amenorrhea for one year 3, 4, 5, 6, 7.
• However, the studies suggest that heavy menstrual bleeding (HMB) can be caused by various factors, including disorders of ovulation, coagulation, or uterine/endometrial causes 3.
• Progesterone or progestogen-releasing intrauterine systems have been shown to be effective in reducing HMB in some women 4, 5, 7.
• Cyclical progestogens have also been used to treat HMB, but the evidence suggests that they may be inferior to other medical therapies, such as tranexamic acid or the levonorgestrel-releasing intrauterine system (LNG-IUS) 6.
• The studies do not provide a clear explanation for why a person who had previously experienced amenorrhea would start experiencing heavy bleeding after initiating progesterone OCP, but it is possible that the introduction of progesterone may be disrupting the body's hormonal balance, leading to changes in menstrual bleeding patterns.

Potential Causes of Heavy Bleeding

• Disorders of ovulation, coagulation, or uterine/endometrial causes may contribute to heavy menstrual bleeding 3.
• The use of progesterone or progestogen-releasing intrauterine systems may affect menstrual bleeding patterns, but the evidence suggests that they are generally effective in reducing HMB 4, 5, 7.
• Cyclical progestogens may also affect menstrual bleeding patterns, but the evidence suggests that they may be inferior to other medical therapies 6.

Limitations of the Evidence

• The provided studies do not directly address the question of why a person would experience heavy bleeding after initiating progesterone OCP when they had previously experienced amenorrhea for one year.
• The evidence is limited by the lack of studies that specifically investigate the effects of progesterone OCP on menstrual bleeding patterns in women with a history of amenorrhea.