As far as I know, there is no short term insurance that would cover a delivery of a baby because it is a pre-existing condition. Any insurance company that sold you this insurance, knowing that it is certain that the baby will be born and they will bear the cost would be losing money unless they sold the insurance for the same price as the cost of delivery.
An emergency travel insurance should be bought for the first 3 months anyway in case an emergency happens. Maybe it would cover an unforeseen pregnancy related emergency but I wouldn't count on it but surely it will cover other emergencies that could be costly like a broken arm or leg.
The procedure to use if the baby is born outside Canada before landing is not to land but instead notify the visa office immediately to add the baby to the application because when a new family member is born, all issued but unused PR visas become invalid. You should absolutely NOT land on the visa you got before the baby was born, after the baby is born because that will mean you can never sponsor the baby.
If you are already a landed PR having a baby outside Canada, you must sponsor it for PR, there is no way around it. A baby born outside Canada will not be Canadian unless one of the parents is already a Canadian citizen. A PR who has to sponsor a baby has a problem because in order to sponsor, they must be in Canada but the baby is often not granted a temporary resident visa to go to Canada with the family because the intention for the baby is not to stay temporarily. Sometimes it is possible to get a TRP for the baby to go to Canada and sometimes the only solution is for one parent to go to Canada and sponsor the baby while the other waits with the baby on the outside. If the baby's citizenship makes it visa exempt to Canada, this is not a problem.