Ovulation – this is the process of egg release from an ovary, it occurs about every 28 days.
The eggs transported through the fallopian tube to the uterus. If the egg is not fertilised by sperm, it will pass out of the body in the menstruation.
This blood flow lasts about 4-5 days due to the breakdown of the thickened lining of the uterus. This lining regrows in the next cycle.
If the egg is fertilised by a sperm in the Fallopian tube, it will begin to divide into a ball of cells. This ball of cells takes 8 days to travel into the uterus where it becomes implanted in the uterine wall. The pregnancy has begun.
The developing embryo is connected to its mother by the placenta. The umbilical cord is an extension of the placenta.
Nutrients and oxygen pass across the placentas to the developing embryo.
- Wastes pass the other way and are eliminated by the mother. The blood of the mother and the baby never mix.
- From 8 weeks until its birth, the fetus grows and matures.
When the baby is mature it is expelled from the uterus by strong muscular contractions. It passes through the vagina and is born. This normally occurs 270 days after fertilisation.