Every month, your body goes through a checklist of things to prepare for pregnancy. During ovulation, the ovary releases an egg which travels through the fallopian tubes towards the uterus. If the egg is fertilized as it travels, it attaches to the uterine wall and starts growing. If the egg remains unfertilized, you get your period.
All of this happens because of rising and falling levels of hormones. Hormones trigger ovulation as well as smaller changes, like telling the wall of the uterus to become thicker so that it’s easier for a fertilized egg to attach itself there.
The hormone in Camila, norethindrone, is a type of progestin. Adding it to the hormones already in your body alters what happens every month. Norethindrone increases the thickness of cervical fluid, so sperm cannot swim through and reach an egg as easily. The progestin in mini pills can also override the normal hormonal cycle, preventing ovulation to begin with.