Birth control pills are a synthetic form of the hormones progesterone and estrogen which are vital to a woman's health and wellbeing. Hormonal birth control pills prevent ovulation by maintaining more consistent hormone levels. Without a peak in estrogen, the ovary doesn't get the signal to release an egg. And without releasing the egg and ovulation, there is no progesterone production. Woman's menstrual cycle is one of the vital sign but when utilizing birth control you're shutting down communication between the brain and ovaries as the production of your hormones switching off.
Effects and side effects are different from woman to woman. But hormonal birth control may affect your strength and performance in the gym, body composition and difficulties to manipulate your weight, inhibits thyroid function and gut health.
The point of this post is not to tell you how hormonal birth control is bad or not. It is up to every woman to decide what's good for their body and health. Of course, many women use pills without any issue or side effects. However, many women do not really know how this works and even don't realize that some symptoms they suffer from, can be caused by birth control pills.
I personally got hormonal birth control at my 16 years and I was using it for 6 years. The only side effect that I remember was probably anxiety. The worse was my post-birth control syndrome and lose of the period for almost 3 years which is a different story.