Is OCP 100% effective contraceptive method?

Oral contraceptive pill (OCP) is one of the best pr eferable contraceptive methods worldwide. And according to studies, it is one of the top effective methods too.  It is said that its efficacy as a method of contraception is 99.7%. Does it mean that those girl or ladies of reproductive age taking Oral contraceptive pill are immune to pregnancy? Don’t they need to take any extra caution like physical barrier method (condom)?

Actually no method is absolute or 100% effective. Even permanent tubal ligation has failure rate!! There are some evidences of conception after tubal ligation!! But tubal ligation is considered as 100% effective method!

For instance, Oral contraceptive pill also has a failure rate as a method of contraception as well. And it is quite high!

But why do these fail? What are the factors behind this failure?

Here we will see some causes of failure of Oral contraceptive pill:

A. Not taking OCP regularly: Irregularity of taking the oral contraceptive pill is one of the causes of failure of this method. When women start taking OCP, her body’s  hormonal (estrogen and progesterone) levels are controlled by these external hormones (OCP may either contain estrogen, or progesterone or both). So if she misses any pill for a long period (even more then 2 days), her hormonal levels harmony in body for preventing ovulation as well as conception will be altered/or disturbed. Meanwhile, if she has unprotected sex, there is higher chance of  becoming pregnant.

 

B. Not taking OCP timely: When doctors give advice for OCP, it is usually to take pills at a fixed time in each day. For effective result this should be followed. Why is this necessary?

Among many other reasons (making cervix of uterus unfavorable or hostile to sperm, change environment of uterus etc), preventing the release of matured ovum from ovaries is the main goal of using oral contraceptive pill. For ovulation, two other hormones (FSH and LH) interplay.  Actually estrogen and progesterone of OCP suppress the activities of FSH and LH and thus they (OCP) prevent ovulation.  No ovulation, no chance of conception. For optimal suppression of FSH and LH, optimal concentration of OCP is required in blood.

That's why if any pill misses, then there will be alteration of hormones levels in blood. No effective suppression of FSH and LH. There will be Ovulation and consequently chance of conception.