The possibility of getting pregnant while you are on your period is very low. However, technically it is not impossible because some factor may occur like the length of you menstruation cycle or the time of your ovulation.
What happens during your menstrual cycle is well known. Your ovaries develop an egg which will be released during you ovulation period. The period of the menstrual cycle if of 28 days but the average is between 23 to 25 days.
You may have already experienced the irregularities of your cycle meaning that in some months your period may be shorter that normal while in other it can be longer. On the other hand your ovulation period can also vary. The normal period of ovulation is in the 14th day of your cycle but because of the fluctuations of your reproductive hormones this can also vary even if you have a normal period.
Possibilities when you can get pregnant during your period
1. If you have a short menstrual cycle
You will start ovulating on the 14th day of your cycle regardless of the length of you cycle. So, if you have sex before and during your period there are some chances that you will become pregnant.
2. Long-life sperm
The normal life of sperm after you have had sex is about 3 to 4 days, up to 7 if the conditions are appropriate. If the sperm survives longer than 4 days, the possibilities of fertilizing an egg are achievable. That is why if you have sex during your periods and the sperm survives a longer period of time you can get pregnant.
3. Long menstruation period
Most women menstruate from 2 to 5 days however it can extent to 7 days and still be considered normal. You may experience a period of 10 days of bleeding which means that if you have sex during this period and then you ovulate you may conceive.
4. Spotting during ovulation
When the egg is release during ovulation some women can experience some spotting of a pink/brown color. Some can mistaken this with their period which is not the case at all. Since you are the most fertile after your ovulation, the chances of getting pregnant are very high.
A lot of women fall into the routine of charts thus having sex only before and after they ovulate when they are trying to have a baby. Since it has been proven that you can get pregnant also during your period the best advice is to have sex every couple of days.