Can a girl get pregnant with another neither one having their period yet?

It is extremely unlikely for a girl to get pregnant without either one of them having their period yet. This is because pregnancy requires the fertilization of an egg by sperm, which typically occurs during ovulation. Ovulation usually happens around 14 days before the start of a menstrual period. Therefore, it is very rare for a girl to ovulate and become pregnant prior to having her first period.