Explain the role of oxytocin and relaxin in parturition and lactation.

Explanation

Relaxin is the hormone secreted by placenta that cause the contraction of pelvic joints and promotes parturition (child birth).
Oxytocin causes the Let-down reflex - the actual ejection of milk from the alveoli of mammary glands. Oxytocin also stimulates the uterus to regain its pre-pregnancy size after child birth.