Hi,
I understand your concern.
Norethindrone is a birth control pill containing a synthetic progestin hormone. It will prevent ovulation and cause changes in cervical mucus and uterine lining to prevent sperm fertilizing the released egg.
It is recommended to use it everyday regularly at the same time.
If you forget, please take the pill as soon as you remember. If the time of taking it is near, then, wait until you take the dose at the same time.
If you take regularly each day, then, no problem for unprotected sex, unless you forget to get the dose. In this case, if unprotected sex was 2-3 hours after a missing dose, you have chance to get pregnant.
If you get pregnant, stop taking the pill in order to prevent
uterine bleeding. If you do not know if are pregnant, no harm will cause to your baby unless bleeding or severe uterine contractions are present.
Hope it answered to your queries.
All the best!
Dr.Albana