Have you sorted out why this is such a burning desire of yours? Are you consciously or unconsciously testing your husband with a subtle "Do you still love me enough to make another baby?" That may not be the issue at all. But it's worth asking yourself why you want another baby so badly. What does a third child give you that two children do not? What feels incomplete? Is it that you always wanted a girl? Or is it something else? How many siblings do you and your husband have? What were your experiences that shape both your feelings today? Exploring these questions may help you and your husband walk through this decision better together.
We had our one and only child when I was 36, almost 37. My mom's parents were in their late 40s, in the 1920s, when she and her sister were born. So, although age is a factor, it doesn't need to dictate. Risks do rise as you get older but there are also plenty of children born to older parents these days that are wonderfully healthy. You just need to discern if you both are willing to take the risk and how you will react if things don't go well health-wise.
A few things to consider regarding age:
1) You may be wiser as an older parent but you may also have less energy.
2) Our 12-year-old complains about us being "so old" at 49 and 55 when he wants to go out and run around and we've got some ache or pain or are just plain tired. Plus, he has no cousins his own age (his main complaint)--they range from college age to 40.
3) How old will you both be when your youngest graduates from high school and college? How does that feel?
4) Are you both ready to start all over again with the diapers and no sleep at night?
5) If you end up having a c-section, your body won't bounce back as quickly as the first and second times. (For that matter, that's probably true of a vaginal birth as well. : )
We always wanted two children but that wasn't in the cards. That saddens us but we feel whole as a family at this point. We make it feel whole by having lots of kids at our house frequently. We also both do a lot of volunteer work in the community.
We once asked our neighbors across the street, who have five children, at what number did it start getting harder? They chuckled and said when they outnumbered the parents. With two kids they could divide and conquer. But with 3, 4, and 5 kids, they had to be more creative with their energies and coordination. Plus, car space began to dictate how big or how many cars were used when going some place.
I was the last of six kids. There were five kids in six years, then...surprise...me five years later. So I grew up in a large family but was also an only child, of sorts, for six years (my older sister was a year ahead in school). That had its plusses and minuses, but that's something to consider as well.
Deciding to have another is a two-way street. It takes two to tango and two to enjoy and struggle with the outcome. Ask questions that explore your hopes and fears, the challenges of remaining a family of four or of growing to more. Allow some time for both of you to think about this independently and together. This is a great opportunity to truly discern what works best for all of you--you and your family.