The answer is: Easier;they are more mature and their relationship is more stable
Having a kid would give a certain level of new demand or pressure for new parents. Couples who stay for a long period of time before having kids tend to have more understanding regarding each other weakness and had more willingness to sacrifice for one another.
Because of this, it would be far easier for couples like tom and julie to make adjustment in their new schedule while providing emotional support for one another to handle the pressure.