North American Registry of Midwives (NARM) Practice Exam

If a woman is experiencing breakthrough bleeding in the first half of her cycle while on OC pills, what is this likely due to?

1. Increase in estrogen

2. Estrogen deficiency

3. Excess progesterone

4. Normal hormonal fluctuations

The correct answer is: Estrogen deficiency

Breakthrough bleeding during the first half of the menstrual cycle for a woman on oral contraceptive (OC) pills is often associated with estrogen deficiency. OC pills work by delivering a combination of hormones—usually estrogen and progestin—to prevent ovulation and regulate the menstrual cycle. If the dosage of estrogen in the contraceptive is insufficient or if the body is not adequately absorbing the hormone, it can lead to a thinner endometrial lining. This can result in irregular shedding of the lining, causing breakthrough bleeding. In the first half of the cycle, when estrogen levels are typically at their peak (if the pill contains estrogen), a deficiency can cause instability in the endometrial lining. The estrogen is essential for maintaining the integrity of the uterine lining. When levels drop too low, it can trigger withdrawal bleeding, which is not part of the normal menstrual cycle for those on OCs. Understanding this mechanism is crucial for midwives and healthcare providers when evaluating patients' experiences with their contraceptives, as it assists in determining whether a change in the method or dosage may be necessary for better management of their symptoms.