When a girl has her first period, it is a sign that she is fertile – capable of having a baby. A girl can actually become pregnant before her first period too, because she ovulates (releases an egg) before her first period.
Women have a period about once a month – this is called the menstrual cycle.
The length of the menstrual cycle can vary, from 21-40 days.
Ovulation (release of an egg) occurs 12-16 days before the next period. This is the most fertile time of the cycle – the time that a woman is most likely to become pregnant if she has sex.
It is very difficult for young women to predict when they might be fertile, because their cycles can be irregular for a few years, before they settle into a regular pattern. It is possible for a woman to become pregnant before her first period, particularly if she has irregular periodor a short menstrual cycle.
The female egg can survive for 24 hours. Sperm can survive for 5-7 days in the female body. Therefore a woman can become pregnant 7-10 days each month.
To learn more, do the Female Body Quiz