If you have sex without using contraception, you can conceive (get pregnant) at any time during your menstrual cycle, even during, or just after, your period.
You can also get pregnant if you have never had a period before, during your first period, or after the first time you have sex.
There is no "safe" time of the month, when you can have sex without contraception and not risk becoming pregnant.
However, there are times in your menstrual cycle when you are at your most fertile, and this is when you are most likely to conceive.
Your menstrual cycle begins on the first day of your period and continues up to the first day of your next period.
You are most fertile at the time of ovulation, (when an egg is released from your ovaries) which usually occurs 12-14 days before your next period starts.
This means that it may be possible to get pregnant soon after your period finishes if you ovulate early, especially if you have a naturally short menstrual cycle.
You should always use contraception when you have sex, if you do not want to become pregnant.
Menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles.
The first day of menstrual bleeding is the date used for the last menstrual period (LMP).
The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults (an average of 28 days).