If you don't have the Child Bed, then the pregnancy event will be postponed beyond 30 days until you have the baby's bed built.
Even if your character is the one that is pregnant, you still have to take care of the farm. You won't lose extra stamina because of your condition; the game plays as normal.
The pregnancy will be 60 days, which is two days short of two seasons. In the morning you will be transported to Klaus' clinic, where you'll learn the baby's gender and then choose its name. Your spouse will not offer to name the baby like in Tale of Two Towns, so it is up to you to pick a good name. The baby will always appear wrapped in a blue blanket whether it is a girl or a boy.