Mums, if you find an usual number of men's numbers in your helper's diary, is this something you would worry about? How would you investigate? Or would you just question her?

Yes, I would be cautious. Then again, you shouldn't have been snooping on your maid and intruding her privacy. If you have a CCTV, do monitor and see if she is bringing anybody home. Also, she won't be able to escape the biannual medical check-up if she's pregnant.