In this instance the gestation had not been prolonged, the delivery was spontaneous, and there was no laceration of the parts.
Chubb says that on Christmas Day, 1852, there was a child delivered weighing 21 pounds.

The labor was not severe and the other children of the family were exceptionally large.

Dickinson describes a woman, a tertipara, who had a most difficult labor and bore an extremely large child.

She had been thirty-six hours in parturition, and by evisceration and craniotomy was delivered of a child weighing 16 pounds.

Her first child weighed 9 pounds, her second 20, and her third, the one described, cost her her life soon after delivery.
There is a history of a Swedish woman in Boston who was delivered by the forceps of her first child, which weighed 19 3/4 pounds and which was 25 3/4 inches long.