There are many stories to explain the reason this prohibition for our family but the essence is to understand it.
It is simple as follow:
It is said that if any lady brake this rule, the baby will grow up with handicap with their arm and legs and would not be able to walk. Based on the family history, over the last 2-3 generations, there are at least 3 persons who were known to defy this rule and their babies could not walk properly.
Hence, this rule is to be strictly followed.
In Australia, when the ladies are having thei baby and staying in hospital, they are supply with bell to ring if they want to call the nurse as they cannot use the normal electric buzzer. Some lady even goes to the toilet at nigth in the dark as they could not turn on the light.
Our relatives in China told us recently that they are still practicing this rule but due to their hardship, they have shorthened the time to 5 days for boys and 3 days fro girls.