As mentioned it’s an attempt to note the pressure without doing direct interviews.

And not to disparage you or cast aspersions, but if you think about why you do not have a fourth kid it’s likely that “have to get new vehicle” could be part of it.

Of course, when you come around from the other end (fourth is on the way, what do) you then change the equation and work it out.

To test the theory presented in the study, we should issue minivans with car seats to new parents; since they have a vehicle large enough they should statistically have more kids than the median.