What Causes Breakthrough Bleeding?

Written by yvonnethornton on December 24th, 2012

Vaginal bleeding outside the schedule of your normal menstrual cycle is always disconcerting. Many women feel a rush of panic when they notice blood on their underwear during a random trip to the bathroom, and rightfully so. Bleeding is usually a sign that something is wrong with us internally. If you’re not on birth control, you should see your physician immediately to make sure nothing is wrong and also to receive a pregnancy test. If you’re bleeding randomly and you are on oral birth control medication, this is probably breakthrough bleeding or spotting. Though it’s frightening, it’s actually not something you should be overly concerned about. It’s common, and it’s a harmless side effect of contraception. Of course, it will still be a surprise when you notice it, so learning the cause might help you feel less worried when you do notice a bit of abnormal bleeding while taking contraception.  As always, with breakthrough bleeding, abstinence or an alternate form of contraception is in order.

Studies show that breakthrough bleeding on contraceptives is caused by the hormones they produce, such as lower dose progestins, which are forms of synthethic progesterone. Since the 1960s , the estrogen dose in oral contraceptive has decreased from more than 150 mcg of ethinyl estradiol to 35 mcg or less. The reduction in dose of the hormone has reduced the incidence of venous thrombosis and clots but also increased the incidence of breakthrough bleeding because of the lower dosage.  Without enough hormone to stabilize the lining of the uterus, the lining prematurely sheds causing breakthrough bleeding (metrorrhagia).  Progesterone-only implants and vaginal rings particularly have an increase in the prevalence of breathrough bleeding, specifically with the active component of etonorgestrel.  To solve this problem, many women find it helpful to go on a different type of contraceptive with a different ratio of hormones to see if their body might react differently.

If you do notice large amounts of blood outside of your normal menstrual cycle, you need to contact your  gynecologist. Though it might be normal spotting caused by your birth control, there is also a chance that it could be a sign of something more serious, or even pregnancy. If you find out it is in fact caused by your contraception, speak with your gynecologist who may switch brands, doses or types of hormonal contraception. In addition to making you worry, spotting and breakthrough bleeding is extremely inconvenient, so the sooner you solve the problem the better off you’ll be.

You can read more about abnormal bleeding and contraception in my women’s health book, INSIDE INFORMATION FOR WOMEN, now in paperback.

 – Yvonne S. Thornton, M. D., M. P. H.

 

 

Leave a Comment