One week after your wedding ceremony, Rebecca will have the Child Bed blueprint for sale in her shop. The blueprint costs 3200 G. To construct the Child Bed, you will need to combine 10 Black Lumber, 5 Suffolk Wool, 10 Alpaca Wool, and 1 Pink Diamond. Your Double Bed will be moved closer to the clothing closet to make room for the Child Bed in the corner of your farmhouse. The flower Vase will move from near your kitchen to between the two beds. Also, a third chair will be added to your dining room table.
After you have the Child Bed built, the next thing you need to do is wait. The pregnancy event will trigger 30 days after your wedding ceremony. A season is actually 31 days, but the pregnancy triggers at 30 days. In the morning when you wake up, you and your spouse will go to Klaus' clinic to discover the reason for an uncomfortable sickness. The doctor will announce the pregnancy, and the two of you will then return home to play through the rest of the day. Pregnancy can trigger on festival days.