Why Birth leads to death?

Why birth leads to death? Though child is born with nine months pain There is no other path. As no one can gain, The Life after death The world end every breathe. So,Love everyone as you love yourself. As there would be no one to help. To escape from death. The richest, the poorer, the mighty ,the loser, the prettiest, the ugliest,the holiest ,the sinner ,the aged or youngest. Everyone meet its end . So,lets Live happily in this world happily.