Gestation period is of 280 days (in rabbit 28 days). Parturition is the expelling of fully mature young ones from the mother's uterus.
Oxytocin stimulates the uterine contraction. It is called labour.
On the completion of gestation, labour starts. It causes labour pain.
Diaphragm is helpful in parturition. It is completed. Parturition may be devided into 3 stages -
1. FIRST STAGE (DILATION) -
It lasts for about 12 hrs. Uterine contraction move the foetus down toward the cervix which expands fully.
Amnion & chorion are reptured. Amniotic fluid passes out, lubricate the vagina.
Foetal placenta is pulled out from the uterine wall, making the young free.
2. SECOND STAGE (EXPULSION) -
Duration is of 20 minutes to 1 Hr.
Due to more contraction waves, the young one is pushed out word through the dilated cervix & vagina, with the head foremost and is finally delivered (born).
Relaxin dilate pelvic muscles. Umbilical cord is cut off.
3. THIRD STAGE (PLACENTAL)-
Duration is 10-45 minutes, after infant's birth. Now uterus begins to shrink.
Placenta, umblical cord & foetal membranes are expelled by another series of uterine contraction.
Now bleeding is stoped. In about 28-35 days, uterus returns fully to its normal size.
Note :- In cesarean section, the baby is removed through a cut given in the mother's abdomen.