This is the period between conception(implantation) and birth.
It last nine months.
Foetus become active between 1st and 20th week.
By 26th week, the foetus is fully formed and has high chances of survival if born prematurely.
During gestation period,zygote develops into an embryo and finally into a foetus.
The proactive hormone/lactogen hormone promotes milk production in mammary glands in preparation for lactation.
At the end of gestation,oxytocin is released from the posterior pituitary glands and it stimulate contraction of uterine muscles.