Husband dropped a bombshell

So I just turned 40 in September And my husband will be 47 in March. I am 38 weeks pregnant today with our 4th boy. We had been trying for about 8 months to get pregnant because we wanted one more addition to our family. We have an 18,9 and 5 year old. We have had extensive talks about this being our last baby because of our age and I signed the paperwork to get my tubes tied after I deliver via C-section.

So out of the blue he tells me not to get my tubes tied that he wants to have one more kid like as soon as possible after this one. WTF?! He was the one who was sooooooo against having anymore kids because of his age and now all of a sudden he wants one more?? We've had so many talks about how sad I am that this is my last pregnancy and last baby and he's always like oh well... I'm just so confused now and don't know if I should tie my tubes or not.. what do you guys think is going on with him?? I asked him and he said he wants the little one to have a sibling close in age..