I don't eat the birth control pill at the same time everyday, what will it affect?

Question: I am taking the birth control pill every day at bedtime, but rarely on time.

Sometimes, I eat early no more than two hours. Sometimes, I eat late no more than two hours. What will it affect?

Answer: Eating birth control pill that is not punctual. It may affect the efficacy of oral contraceptives because drug levels in the blood are not steady. So if you want fully effective contraceptives, you should take your birth control pill at the same time every day.

Reference:

http://www.cdc.gov/reproductivehealth/unintendedpregnancy/contraception.htm#Hormonal-Methods