Breakthrough bleeding is bleeding that is not regular or not expected between menstrual cycles. It occurs while a woman is taking oral contraceptives or birth control containing hormones. While the reason behind some breakthrough menstrual bleeding remains a mystery, there are many known reasons that explain its occurrence. Understanding the causes can help educate birth control users on behaviors and actions that can increase the chances of breakthrough bleeding.
Hormone Adjustment and Adaptation
Breakthrough bleeding is most common shortly after a woman begins oral contraceptives. In fact, almost one-third of women who quit taking birth control pills do so because of bleeding problems that include breakthrough bleeding, according to Dr. Frederick R. Jelovsek, a contributing writer for Women’s Health Resource. The Journal of Family Practice website explains that progestin and estrogen in contraceptives greatly affect a woman’s endometrium, the inner membrane of the uterus, and can lead to breakthrough bleeding. The good news for women who prefer this type of contraceptive method is that breakthrough bleeding rates do decline after the first three months of use, once the body has adapted to the contraceptive hormones.
Patient Compliance
Forgetting to take a pill or forgetting to take it around the same time each day can lead to breakthrough bleeding, according to the Journal of Family Practice. While missing just one pill only slightly raises the chances of breakthrough bleeding, more than 80 percent of women who skip three pills in a cycle will have some sort of bleeding.
Smoking
Women’s Health Resource points to a relationship between smoking and breakthrough bleeding in women who take oral contraceptives. In addition, breakthrough bleeding for smokers appears to become more prevalent with time. By the sixth month of pill use, smokers have breakthrough bleeding about twice as often non-smokers. It is also important to note that breakthrough bleeding frequency is even worse for heavy smokers, or those who smoke more than 15 cigarettes per day.
Implantation Bleeding
Breakthrough bleeding is often difficult to distinguish from implantation bleeding, which occurs when a fertilized egg implants itself in the uterus. Because the bleeding closely resembles implantation bleeding, it is hard to tell if pregnancy has occurred.
Endometrium Thinning and Low Estrogen
It is thought that breakthrough menstrual bleeding could also be the result of atrophic bleeding, or bleeding caused by endometrium thinning. Women’s Health Resource explains that birth control pills lead to low estrogen levels, which in turn thin the endometrium to the point that even the slightest abrasion from normal activity can cause breakthrough bleeding.
