Hi - I turned 40 over the weekend and I am due next week. (I actually thought labor was starting yesterday morning -lots of BH contractions- but no baby yet!) I plan to nurse this little guy for a while, and as of right now, my DH and I are planning to try for one more after that. We have a large family - this new baby will be number 9, he will be the seventh biological and we have two adopted - and it works out great for us. If you are really committed to the idea of another person in your family and your partner is as well, I think your other two kids will be fine.
I remember hearing one time on this subject that you never really hear of a family that "didn't work out" because of the age range between children, or how many children are in the family, as long as both partners are filled with love for the children.
I am sorry I can't add anything about the hernia, but I am sure your doctor could help you decide what the risks are if you decide to become pregnant again.
Best of luck - it's a big decision! Marirose
I'll let you know how labor/delivery goes as a forty year old as soon as I find out!