Lets think about this.... Ideally, it would be that no you couldn't because you would have ovulated on the 14th day, and since no egg was fertilized, you have a period..... Unfortunately, for some, that isn't always true. It is now said that not all women ovulate on the 14th day or in the middle of their cycle. With this being said, it is possible to have a period and ovulate. I am thinking its unlikely, but still very possible. One way to know if you ovulate, is to watch your fertile signs... (ie cervix mucus, temp... etc, the girls here know better about that, and there is a book) Other than that, there is no sure way to tell when you ovulate. Therefore, haveing unprotected sex on your period isn't a good form of contraceptive...
Dani06wc is right. It is possible to become pg on your period if you have irregular or very short periods. The relationship between the start of your period and the date of ovulation can and will change depending on the regularity of your periods but you will always have your period about 2 weeks after ovulation. During a very short period of say 22 days you could become fertile several days (say 3 days) ahead of ovulation which would be on CD8. CD8 minus 3 would be CD5. If you were still having your period on CD5 and you had IC then you would also have fertile mucus present in which sperm could live for 5 days, more than enough time to meet and fertilize your egg on CD 8 or 9. The thing to remember is that you ovulate about 2 weeks before you start your period. The only way you can tell for sure when you ovulate is if you are charting your temp. and see the rise in your temperature at ovulation. A really good book on the menstrual cycle is Toni Weschler’s Taking Charge of Your Fertility. Does this help?
Hope i helped a bit
Goodluck
Dani06wc is right. It is possible to become pg on your period if you have irregular or very short periods. The relationship between the start of your period and the date of ovulation can and will change depending on the regularity of your periods but you will always have your period about 2 weeks after ovulation. During a very short period of say 22 days you could become fertile several days (say 3 days) ahead of ovulation which would be on CD8. CD8 minus 3 would be CD5. If you were still having your period on CD5 and you had IC then you would also have fertile mucus present in which sperm could live for 5 days, more than enough time to meet and fertilize your egg on CD 8 or 9. The thing to remember is that you ovulate about 2 weeks before you start your period. The only way you can tell for sure when you ovulate is if you are charting your temp. and see the rise in your temperature at ovulation. A really good book on the menstrual cycle is Toni Weschler’s Taking Charge of Your Fertility. Does this help?
Good luck
Jill