The drive to nest—a sudden burst of energy to clean and organize—can happen any time in pregnancy, but it’s most common in the third trimester and increases with every passing week. Some moms find nesting peaks in the week or two before birth, while others have no desire to nest at all.
In fact, there’s not a lot of evidence that nesting is a real hormonal or biological phenomenon. Instead, the nesting instinct may simply be a way for some parents to control their environment and feel more psychologically prepared for birth and the life changes to come.