Puberty

Human body growth 

The reproductive organs are very different between men and women, even babies have reproductive systems. We call them our primary sexual characteristics. Between the ages of 8 and 15, our bodies dramatically change. These changes are called secondary sex characteristics.

Male secondary sex characteristics include muscle gain, voice change, hair growth in the pubic region, and growth of armpit hair and facial hair, like beards and mustaches.

Female secondary sex characteristics include wider hips and breast development, increased body fat composition, hair growth in the pubic region, and the menstrual cycle.

The testicles make the main hormone in a man’s body, called testosterone, and it helps change the male body’s secondary characteristics.

The ovaries make the female hormones, called estrogen and progesterone. Estrogen plays a big role in reproductive and sexual development including menstruation and pregnancy, and influences our skin, hair, and bones. Progesterone supports the reproductive system.

When we are children, we can’t have babies. As we get older, our bodies change to be physically mature so we can make babies. For girls and women, menstruation is a necessary function to make children. Of course, menstruation is important for boys too.