Under the influence of oxytocin,which layer of the uterus exhibits strong contractions during parturition?

Statement $P$: Mother's milk is very essential for a newborn infant.
Statement $Q$: The secretion of colostrum contains abundant antibodies.

Ovulation does not occur during the lactational period because of:

Which hormone is secreted at the time of parturition?

$A$: Colostrum is a very efficient means of transferring immunity to a newborn.
$R$: $IgM$ from mother's milk protects the baby from the respiratory infection usually affecting in young age.

What is parturition? Which hormones are involved in the induction of parturition?