In human reproduction, we can distinguish several stages. Fertilization
produces an egg which, with cell
division, turns into an embryo. This embryo continues its growth nestled in the endometrium
of the uterus and becomes a fetus when the major organs and tissues are formed, in other words, after the third month of uterine life. The fetus develops in the womb, in the middle of a bag containing the amniotic fluid
and nourished by the placenta
. The fetus stage lasts until labor, with the birth
of the newborn and the development of the infant. A fetus that is born before 22 weeks of gestation (from the start date of the last menstrual period) is considered unable to survive.