Dr. Zulfiqar Ali Shah, Member of the Executive Committee of the Fiqh Council of North America and the Religious Director of the Islamic Society of Milwaukee, states: The Sunnah of cutting the hair on the seventh day is also scientifically proven to be good for the hair growth of the child. The baby had lived with this type of hair in mother’s womb for several months with all the chemicals present in the womb, and shaving the baby’s hair guarantees the proper growth of the hair and it is quiet safe to cut the hair on the seventh day as the head skin becomes quite strong and capable of shaving on the seventh day. You could seek assistance of a barber or a better trained person in your family and get it down. The Prophet (peace and blessings be upon him) would not recommend something which is against the well-being of a baby. Moreover, the baby’s skin is very self-protecting and it heals immediately even if there were any minor scars. Therefore, don’t worry and get it down on the seventh day or afterwards because it is good for the health of the baby.
Specified weight for the hair is not fixed; it is just a charity and it is an expression of gratitude for Allah for the safety of the newborn.”