Lots of women have babies after 40 without Down's Syndrome, but it can happen. It can happen at any age, though.
Regarding your missed period, I'd contact your OB or doctor to have a blood test drawn so you can know whether or not you are pregnant or if something else is causing you to not have a period.
Good luck!
Hi mjp2014,
I just finished reading your comments. Okay, so your daughter will be about
fifteen years old. Children are such a blessing. You probably already know
this, but after 40 years old, there is a chance that any baby you have may
be born with down syndrome. If you still want to conceive knowing this may
be a possibility, that's your decision of course. Just think of the child and
the child's quality of life. I'm not judging. I'm just trying to bring this issue
to your attention. If I've spoken out of turn, I'm sorry, but I felt you should
be aware of this possibility. I wish you well. Eve