Usually the male gamete sperm and the female gamete ova will be fused to form zygote. this is the first process in the pregnancy period.then the cells begin to form groups that develop into tissues and organs in the body this results in embryo, this embryo develops continueosly in the uterus. and this gradually develops into the legs eyes body brain and the body parts,when this formed it is called as foetus.and it gives a baby off.the main for this pregnancy is the fusion of male and female gametes.