Reasons against:
Lots of jobs that need doing in the house...
Our one child wears us out as it is....
Middle bedroom is full of crap we'd have to clear out....
Money is quite tight and our crippling loan is not paid off for a year...
It was very stressful being off work (my maternity cover kept changing things...)
I have problems with my arms and hands - could I cope with a 4 or 5 year old and a new baby
Childcare would almost double...
Everything will take twice as long... and it takes forever now....
My Mum and Dad don't think we "are ready for number two"
Pregnancy is uncomfortable....
Birth blumin hurts....
Reasons for:
We (all three of us) really want another baby 
Your thoughts as big families would really help.