What age would you consider it be too old to marry if want children?Watch this thread
I would want to get married in my late 20s/early 30s but then wait till it's financially feasible for us to afford a pretty good upbringing for our children (perhaps 2-5 years after marriage). So I guess the latest for me would be 35 (I'm a woman). There are other methods that you could use if you wanted children later on in your life - adopting (maybe fostering too), IVF, embryo/sperm banks, surrogate mothers, etc. But obviously, these have their own personal ethical, financial and moral considerations too.
There are other methods, but you need to be prepared to pay for them. Where I live, IVF will only be considered for people up the age of 38 on the NHS, and you need to have been trying for at least 2 years before you can be referred.
If anyone finds that they are not able to conceive you should take advice from a GP or another specialist to figure out the best course of action for you - I'm obviously just an anonymous person on a TSR thread! Perhaps also look into family planning if you would like.
Medically, the risk of down syndrome starts to increase if a woman has a baby past the age of 35, but I don't necessarily think it's wrong to have a baby in your late 30s, it's just that there are a few more things to think about.
I think ideally having them before 40 is preferable, both medically, and for other reasons, but I try not to judge people.
I had mine quite young (married at 21, and had kids at 21, 23, 25, 29).
You don't actually have to be married to have kids though, you know that, right?