They had more vigorous sex in the new timeline.
www.jrichardsingleton.blogspot.com

He didn't have sex with his wife as often in the original timeline, because he did not spend as much time with his wife as a younger man in the original timeline.

Very well put.

And difficulties in this area seem to cut deeply into our self identity and weigh heavily on us. People really don't get that. Stein was saying that he told his younger self the importance of a legacy, of being connected to something great than just himself but still in many ways is inexorably a part of him.

Both my wife and I have fertility issues and it took seven years for us to have children, and that included a miscarriage. So no, as others have pointed out, that's not necessarily true at all.

A lot of couples need to plan to have a baby. Like having sex during peak ovulation etc.
You'd be surprised how making babies is either really easy (i.e drunk and even with condoms you still get preggers )
or you need to plan it and do regimented times for sex.

Unprotected sex
A Cosmic Experience:

Yep cause you can't have sex without having a baby that's why in the new timeline he only went to pound town that one time
JP

I just think he was more into his work and didn't care for kids, not in the altered timeline he was just crushing his wife's puss all day. that beep would knock up your neighbors.