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if used appropriately is very effective & 99% women do not conceive. But, in rare instances, NuvaRing may fall out during sexual intercourse, while straining before or during a bowel movement, or while removing a tampon & the risk of pregnancy
efficacy is also reduced if the ring is removed, accidentally expelled, or left outside of the vagina for more than three hours. So, if you have missed a period you must consider the possibility that you are pregnant & do a pregnancy test.
If you suspect you are pregnant, please do not use new NuvaRing & see your doctor as soon as possible.
Some drugs also decrease its effectiveness like some antibiotics, certain medicines that are taken by mouth for yeast infections
, certain HIV medicines, certain anti-seizure
medicines, St. John's wort etc.
So be brave & do a test.