Signals from fully developed foetus and placenta ultimately lead to parturition which requires the release of

Signals from a fully developed foetus and placenta ultimately lead to parturition,which requires the release of:

Which hormone is secreted at the time of parturition?

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$ :
Assertion $A$ : Breast-feeding during the initial period of infant growth is recommended by doctors for bringing up a healthy baby.
Reason $R$ : Colostrum contains several antibodies absolutely essential to develop resistance in the newborn baby.
In the light of the above statements,choose the most appropriate answer from the options given below:

Following features are seen during the dilation stage of parturition $EXCEPT$ . . . . . . .

Explain the process of lactation.