In my case, we had our first, a boy, and he was 2 1/2 years old. We had always planned to work on #2 at that time, and when that time came, it was ME that wasn't ready. I wasn't ready financially or emotionally and it takes time to overcome both of those issues. We had JUST begun to get on our feet after years of struggling and I was the only one working at the time this happened. I couldn't see pulling our whole financial train and being a wife, mom and pregnant. It was a recipe for disaster.
He pushed, and brow-beat me, and pushed, and made me feel guilty for not doing things "as planned" and I finally felt so guilty that I gave in. I was terrified and felt as though I'd regret NOT having #2, and yet was terrified that HAVING #2 would be a terrible decision.
Right after I got pregnant (which took 2 months), he changed his tune and decided he wanted to go to Grad school instead of work until the baby was born and have him be a stay home dad (which we'd agreed would be the only way having #2 would work), and I'd finally had it with him. I left him when I was 8 weeks pregnant with our daughter. I chose to have her, and accepted being a single mom of 2 kids under 4 yrs old, instead of staying married and being a single mom of 3 kids under 35 yrs old.
Ultimately, him NOT being responsible and NOT taking our family finances and responsibilities seriously is what led to our divorce. Yes, getting pregnant was also my choice, but honestly, I didn't feel as though I had one.
Talk about it with your husband and don't think that just because you have 1 child means he's ready for a 2nd.
Best of luck
C.