During childbirth, a hormone produced by the pituitary gland causes muscles of the mother's uterus (or womb) to contract. the more contractions there are, the more hormone is produced. which best explains why this occurs? a. positive feedback is used to build more contractions. b. positive feedback is used to lessen the effects of the contractions. c. negative feedback is used to build more contractions. d. negative feedback is used to lessen the effects of the contractions.