Final answer:
Oxytocin stimulates uterine contractions during childbirth, but hypertonic contractions can be detrimental to the fetus by reducing placental blood flow.
Step-by-step explanation:
Oxytocin is a hormone that stimulates uterine contractions, which are necessary for childbirth. These contractions help push the baby towards the cervix and eventually out of the uterus. However, one side effect of oxytocin stimulation is hypertonic contractions, which can be detrimental to the fetus. Hypertonic contractions are very strong and can reduce placental blood flow, potentially putting the fetus in distress.