We had our two DCs eventually quite easily after a couple of years of stress and miscarriage which had made me feel as if I would never have children.
DH felt that we were a perfect family unit and wanted to have a vasectomy. I didn't really want another, I can't say I was broody exactly: I quite liked the idea of another, but not enough to make an issue of it.
However I really didn't want him to have a vasectomy. I feared that the knowledge I couldn't have another child would feel like the "I'm never going to have a baby" despair I had experienced before we had our first. So I was against vasectomy and I said to him that they wouldn't do it unless I was sure as well; which I have since learned from Mumsnet is actually incorrect, but I sincerely believed it to be true at the time.
When DC2 started school I got a job I adored, and said to DH OK I am happy with you having a vasectomy. Three months later and he finally got around to booking one. You guessed it, a week before the appointment I found out I was pregnant.
Recriminations followed. I said it was his fault for taking three months to book the vasectomy, he said it was mine for stopping him from going for it earlier just because of my feelings, and expecting him to jump to it the second I graciously gave him my permission. 5 years on I think he might have been more right than me 
I was gutted at having to leave my job. Aside from that, DC3 is wonderful and the best thing that has ever happened. I think I spent the first few weeks of his life weeping as I pondered: "What if DH had had the snip? What if we hadn't got pissed that night? DS2 wouldn't exist! Waaaaaaa!!!!"
DH did get the snip when DS2 was a couple of months old. And every month, when I get my period I have a little sigh, even though I am too old and we don't want a fourth . . .