There is no such thing as a “safe” time during your cycle - if you’re having unprotected sex.
Many people believe that a period works in the same way as contraception and that it is not possible to get pregnant while on your period. However, this is false. Although the chances are very slim, there is a chance that you can conceive during this phase of your cycle.
What Are the Chances of Falling Pregnant on Your Period?
Falling pregnant while on your period is very unlikely. However, If you are having unprotected sex there is a chance you can conceive during your period.
There are several factors that need to be taken into consideration when looking at the likelihood of falling pregnant on your period:
- Whether you had protected or unprotected sex (use of contraceptives)
- The length of your menstrual cycle
- The length of your period
- When you had sex
The likelihood of falling pregnant on days one or two of your period is nearly zero. But the likelihood of pregnancy increases each successive day, even if you’re still menstruating.
Around day 13 of your cycle the chances of you falling pregnant is estimated to be around 9%. Despite these numbers being low, you can never be 100% sure that you will not fall pregnant on your period. 
How Can Someone Get Pregnant on Their Period?
Some women may bleed during ovulation, at a time when they are most fertile. It can be easy to mistake vaginal bleeding for the beginning of your period. Having sex at this point, without contraception will drastically increase the chances of conceiving.
Everything You Need To Know About Menstrual Cycles
Your cycle begins on the first day of your period and lasts until the first day of your next period. Around 10 - 16 days before your next period is due, ovulation will occur (your ovaries release an egg). And it is around this time that you are most fertile. For conception to happen, the sperm has to fertilise the egg within 24 hours of ovulation.
Although your egg will only live between 12 - 24 hours after being released, it is possible to get pregnant even if you’ve had sex days before ovulation. This is because sperm can live for up to five days in your body.
A typical menstrual cycle length is between 28 - 30 days. With a cycle of this length, your fertile window will usually fall between day 11 - day 21. It’s important to note that this can vary as every woman and cycle can be different.
If the length of your period is between 5 - 7 days and you have sex around the end of your period, there’s a chance you could conceive on day 11. As mentioned above, sperm can survive for up to 5 days.
If you have short menstrual cycles you can also fall pregnant after having sex while on your period as a shorter cycle means you ovulate earlier, and closer to the end of your period.
Are You More Likely or Less Likely To Get Pregnant on Your Period?
Overall the chances of someone falling pregnant while on their period are slim, however, this chance isn’t zero. Pregnancy is less likely in the earlier days of your period, with the chances increasing towards the end of your period.
Should I Still Use Contraception During My Period?
Yes! You should continue to use a form of contraception while on your period. Since ovulation has the potential to start prematurely and sperm can survive up to 5 days inside your body, there is still the possibility of pregnancy if you’re having unprotected sex on your period.
It is possible to fall pregnant if you have sex on your period, even if you’re using contraceptives. This is because no method of contraception is 100% reliable. Many forms of contraception are 99% effective when used correctly and if used perfectly.
The only 100% reliable form of contraception is if you abstain from sex (not having sex).
The Likelihood of Falling Pregnant on Each Contraceptive:
- Combined pill - 1%
- Progesterone only pill - 1%
- Vaginal ring - 1%
- Contraceptive patch - 1%
- Condoms (male) - 2%
- Condoms (female) - 5%
- Implant - less than 1%
- Depo (contraceptive) injection - less than 1%
- Diaphragm - 4-8%
- IUD - less than 1%
In conclusion, although the chances are lower, it is still possible to fall pregnant on your period. Using contraceptives correctly can greatly reduce the likelihood of falling pregnant both on and off of your period. But the only way to avoid pregnancy completely is to abstain from sex altogether.
