Normal birth is the birth of a single baby, which comes as a
head-down between 38-42 weeks of gestation, with spontaneous uterine
contractions, without harming the mother and the baby.
In normal delivery, placenta and its membranes are automatically
ejected from the uterus at the latest thirty minutes after the baby is born.
About 300 ml of blood is lost in a normal birth. The time taken for childbirth
is less than 24 hours.
A normal gestation period is 280 days or 40 weeks from the
last day of menstruation. The expected date of birth can be calculated with the
formula "7 days are added to the last menstrual period and 3 months
behind".