1, for two real reasons and one silly reason.
RR #1: I had a very difficult pregnancy, four months of bedrest, dd in distress so induced, dd heartrate crashing with each contraction so had emergency section during which my blood pressure skyrocketed to 210/160. Very real reason is that dh is too scared to try again, and I am as well.
RR#2: We both really like sleeping undisturbed all night and having a child who can go potty independantly. V. selfish, yes.
Silly reason, with background:
I am fat and chronically depressed. Always been since childhood. Dh has a form of dwarfism and is technically a "little person", although he has a wicked sense of humour and calls himself various other things
Our dd is gorgeous. Tall, slim, strawberry blond ringlets and freckles, very very smart (teacher says, not just our opinion). Dh jokes that dd got every good gene we had between us, and were we to try again we might have a fat, angry, depressed, stupid dwarf on our hands.
I know, it's so awful, truly horrible! But I still giggle when he mentions it to me. Am a little embarrassed to have actually posted this.