How successful is levonorgestrel?

Q: I am 20 years old and my normal menstrual cycle length is 29-32 days. This month I took post coital pill levonorgestrel 1.5 mg on the 19th day of menstruation. I missed my this months period. I did a pregnancy test which came negative. Is pregnancy possible or is it due to levonorgestrel? Please help.

A:You have given the date of taking pill but not the date of sexual intercourse. The success rate of levonorgestrel depends as to the time it was taken after unprotected sex: 95% if taken within 24 hours, 85% if taken 24-48 hours and 58% if taken after 48 up to 72 hours. You should repeat the pregnancy test at another laboratory to make sure that the result is correct. Temporary disturbance of bleeding pattern is quite common after taking the pill. It gets corrected in 1-2 cycles. Levonorgestrel use has many serious side effects such as ectopic pregnancy and hence should not be routinely used. It is an emergency measure and should be employed in emergency situation such as involuntary sex. In normal cases, condom by male sexual partner is much safer.