Thank you for your query at AskTheDoctor.com
I understand your concern.
Menarche or the first time a woman gets a period is important as it shows that now a woman has started producing an ovum with a potential to get pregnant.
If she never had a period before or did not attain menarche till now, she won't get pregnant.
A girl normally attains menarche in between ages of 11-14.
Pregnancy is highly unlikely in this age group.
Hope this was helpful,
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