Amniotic fluid index
4 is definitely considered as oligohydromnios, and this can affect the well being of the baby and also can make normal delivery difficult,
so as safe side better to go for cesarean section as told by your doctor,
regarding maturation of the baby no need to worry as by 37 completed weeks it will attain the capacity to survive out side the uterus
as you are almost near completed term, your baby will be good, early delivery will protect the baby from hazards of oilgos, so don't worry be peaceful.