This increase in female sex hormones results in:
the development of breasts
the growth of pubic and armpit hair
an overall growth spurt
an increase in body fat, especially in the hips and thighs
the maturation of the ovaries, uterus, and vagina
the start of the menstrual cycle
Menstruation
The first menstrual period (menarche) happens about two to three years after the breasts begin to develop. Again, it’s different for everybody, but most females get their first period between the ages of 10 and 16.
Follicular phase
Every month, the uterus thickens in preparation for a fertilized egg. When there’s no fertilized egg, estrogen and progesterone levels stay low. This prompts your uterus to shed its lining. The day you start to bleed is day 1 of your cycle, or the follicular phase.
The pituitary gland starts to produce a little more FSH. This spurs growth of follicles in your ovaries. Within each follicle is an egg. As sex hormone levels drop, only a single, dominant follicle will continue to grow.
As this follicle produces more estrogen, the other follicles break down. Higher levels of estrogen stimulate an LH surge. This phase lasts about two weeks.
Ovulatory phase
Next comes the ovulatory phase. LH causes the follicle to rupture and release the egg. This phase lasts about 16 to 32 hours. Fertilization can only occur for about 12 hours after the egg has left the ovary.
Luteal phase
The luteal phase starts after ovulation. The ruptured follicle closes and the production of progesterone increases. This gets the uterus ready to receive a fertilized egg.
If that doesn’t happen, estrogen and progesterone decrease again and the cycle starts all over.
The entire menstrual cycle lasts around 25 to 36 days. Bleeding lasts between 3 and 7 days. But this, too, varies quite a bit. Your cycle may be quite irregular for the first few years. It can also vary at different times of your life or when you use hormonal contraceptives.
Sexual desire and contraception
Estrogen, progesterone, and testosterone all play a role in female sexual desire — also called libido — and sexual functioning. Due to hormonal fluctuations, females are generally at the peak of sexual desire just before ovulation.
There’s generally less fluctuation in libido if you’re using hormonal birth control methods, which affect hormone levels. Your libido may also fluctuate less after menopause.
Undergoing surgery to remove your adrenal glands or ovaries cuts down on testosterone production, which can cause a drop in your libido.
Pregnancy