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What has caused my breakthrough bleeding after missing one pill if I am not pregnant? #203/9
I missed a pill in December and had to take two which caused me to start; the very next week was my week for my period anyway, so I had continued to have my period. I started my pills on the day that I was suppose to and haven't missed a pill, I did however, how sex 8 days after having started back on my pill. When I had taken my pills and was ready for my week of my period, I didn't have one.

I have taken 2 pregnancy tests and they both have said negative. I am worried about an unwanted pregnancy. Is there a possibility of my being pregnant?

As you found out, missing just one pill can start bleeding as noted in #7 below.  Breakthrough bleeding tends to improve over time.  However, missing one pills does not significantly increase a woman's risk for pregnancy. [WHO Selected Practice Guidelines - 2005]


Below is a lot of information about the bleeding a woman on pills may anticipate in the first year of pill use:


What were the results of Dr. Gloria Bachmann’s review of 17 long-term patterns of bleeding based on 90-day reference periods?



1.    Overall, users of pills have the most bleeding/spotting days during the first 90 days, and this decreases by the 4th 90 or 91-day reference period.


2.    Triphasic pills appear to have similar bleeding indices and patterns as monophasic pills with continued use beyond the first 90 day reference period


3.     The most marked fall in the number of bleeding days occurred from the first to the second 90 day reference period.


4.    The number of bleeding/spotting days for combined pills ranged between 10 and 24 days for the first 90 day period, decreasing to 7.5 to 15 days for Reference period 4. 


5.    Interestingly, the 42/7, 84/7 and 126-day continuous treatment regimen were generally associated with the fewest number of bleeding/spotting days during Reference Periods 1 and 4 compared with the 21/7 and 14/4 regimens.


6.    Over time days of spotting/bleeding fell and amenorrhea increased in women using progestin-only pills. 


7.    Poor compliance can lead to unexpected intermenstrual spotting or bleeding - even one pill may cause intermenstrual bleeding.


8.    Intermenstrual bleeding in women previously well regulated on OCs appears to be a good indication for Chlamydial infection (Krettek 1993)


9.    One study showed that smokers were more likely to experience bleeding disturbances with higher incidences of both spotting and bleeding than nonsmokers


What a great paper!  Special thanks to the author of this recent article in CONTRACEPTION.


Pregnancy seems to be your primary concern.  I think you are at very low risk of pregnancy. Missing one pill does not sifnificantly increase your risk for pregnancy. Keep on with your next cycle of pills


Good luck

Now, two weeks later, were we correct that you were not pregnant?

Key Words:  missed pill, period, pregnancy tests, negative, worried, unwanted pregnancy, breakthrough bleeding, cause, improve, pill use, Dr. Gloria Bachmann’s review, long-term pattern

Posted 2-17-2009, Updated 2-20-2009, Updated 3-16-2009 

Robert A. Hatcher MD, MPH
Emeritus Professor of Gynecology and Obstetrics
Emory University School of Medicine
Atlanta, GA

The directors and owners of this website and any publications and information concerning health matters offered here advise a person with a particular problem to consult a primary-care clinician or a specialist in obstetrics, gynecology, or urology (depending on the problem or the contraceptive) as well as the product package insert and other references before diagnosing, managing, or treating the problem.
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