Approx birth month. First month is the month they're conceived and the one beside it is the approximate month of birth, if they're born full term. Handy guide if you want to try to have a baby in a specific month.
You can learn so much about your fertility and optimize chances of pregnancy with fertility charting... And once you've learned how, it takes only a couple minutes a day. Cheap and easy way to help figure out what's going on with your fertility.
A detailed fertility chart for women and their partners who are trying to conceive a baby (TTC). Record basal body temperature and other details key to determining ovulation and peak conception conditions. Free to download and print