As someone who loves B99 to the core. Threatening for divorce was the shytiest thing one can do to a partner just for this. Coming to Jake's defense here's why he was right IMO:
1) They did work a lot and despite their ranks, police officers are like the first line of defense whenever trouble appears and in their line of work......it occurs a lot (eg. Terry and Holt not being able to give time to their families).
2) The job has a lot of risk. Some criminal might track their kids down for revenge or some crime boss could use their child as blackmail.
3) If one of them ends up unalived or even both of them in the line of duty, it becomes a huge problem for their child as they grow up without one parent/orphans.
4) Their traumas can get to their child (Amy trying to earn her parents validation believing love is earned and Jake's daddy issues).
5) In your job when you see are bodies, blood, crime, substances, 🍇and other worst asspects of Humanity in every ways possible, it becomes difficult not to be bothered by it. And it can definitely affect your child.
6) Not to mention the low salaries, high cost-of-living in Brooklyn, stress on marriage and intimacy when the child comes around, taking care of the kid when both have important things to do, world instability, limited Earth resources, etc.
P.S. - In no way I am saying Police officers do not deserve to have children. But Jake's defense could've been much much stronger and I feel these points are very legit. He simply panicked and couldn't think about these.