Can you get pregnant on your period?

Ovulation is the release of an egg from the ovaries. The time between the release of an egg and the start of a period is around 10 to 16 days, so in most women ovulation happens around 10 to 16 days before the next period. The NHS also describes the fertile time as being around ovulation, about 12 to 16 days before the start of the next period.

In a regular 28-day cycle, a woman is likely to be fertile around day 14. That timing does not apply to everyone, because cycles can be shorter or longer. Sperm can also survive in the fallopian tubes for up to 7 days after sex, so the fertile time extends back into the days before ovulation.

Pregnancy happens if sperm meet and fertilise an egg. Because the exact timing of ovulation can be difficult to identify, a GP or sexual health clinic can help if you have questions about your own cycle or pregnancy risk.

Sex during a period can still lead to pregnancy because sperm may remain alive for up to 7 days. If ovulation happens within that time, sperm from earlier sex may still be present when the egg is released.

The chance depends partly on when ovulation happens in relation to the sex. Although ovulation is often described in relation to the next period, rather than the period that has just started, it can be difficult to pinpoint the exact day. This is why the timing of bleeding alone cannot be used to say with certainty that pregnancy is impossible.

If you have had sex without contraception during your period and are concerned about pregnancy, you can speak with a pharmacist, GP or sexual health clinic about the options available after unprotected sex.

Shorter cycles can bring ovulation closer to the end of a period. The NHS says it is possible, although not very likely, to get pregnant soon after a period finishes if you ovulate early or have a short menstrual cycle. Because sperm can survive for up to 7 days, sex before ovulation can still result in pregnancy if sperm are present when an egg is released.

Cycles can normally range from 21 to 35 days, and they do not all follow a 28-day pattern. Fertility calculations based on day 14 therefore do not apply to everyone. The NHS also says fertility awareness may not be suitable if you have irregular periods.

Periods can change, including becoming longer or lighter. The NHS says this does not necessarily mean there is a problem, but it does need to be investigated. If your periods have changed or you are unsure how your cycle affects your fertile time, a GP or sexual health clinic can give individual advice.

Pregnancy is possible from sex without penetration if sperm comes into contact with the vagina. The NHS gives examples including a partner ejaculating very close to the vagina or an erect penis touching the vulva. The risk is described as very low, but it can happen.

Withdrawing the penis before ejaculation is not considered an effective way to avoid pregnancy and is not recommended as a method of contraception. If avoiding pregnancy is important to you, relying on withdrawal does not provide the same approach as using a recognised method of contraception.

If sperm may have come into contact with the vagina and you are unsure whether emergency contraception is appropriate, a pharmacist, GP or sexual health clinic can help you assess what to do next.

Some hormonal contraception works by stopping ovulation. The NHS gives the combined pill, the patch and the injection as examples. A woman cannot get pregnant if ovulation does not occur.

Fertility awareness is another approach. It involves tracking periods to identify when you are most fertile and avoiding sex or using condoms on those days. When used correctly all the time, fertility awareness methods are between 91 and 99 percent effective at preventing pregnancy. If the instructions are not followed exactly, they are 76 percent effective, meaning 24 in 100 women will get pregnant when tracking their fertility for a year.

The NHS says fertility awareness should be taught by an expert such as a fertility awareness practitioner or midwife, and it can take 2 to 3 menstrual cycles to learn properly, with additional contraception needed during that time. Apps and fertility monitoring devices exist, but none are officially recommended by the NHS. Natural family planning does not prevent sexually transmitted infections, and condoms are needed for that. A GP or sexual health clinic can discuss contraception or fertility awareness if you want help choosing an approach.

Emergency contraception can help prevent pregnancy after unprotected sex, meaning sex without contraception or when contraception might have failed. It needs to be used within 3 to 5 days after unprotected sex, and the sooner it is used, the more effective it usually is.

There are two types. An IUD, also called a copper coil, can be fitted within 5 days, or 120 hours, after sex by a specially trained nurse or doctor and is the most effective type of emergency contraception. The emergency contraceptive pill is also called the morning after pill. Levonorgestrel needs to be taken within 3 days, or 72 hours, after sex, while ulipristal acetate needs to be taken within 5 days, or 120 hours.

Emergency contraception is free from NHS sexual health clinics and GP surgeries, and the emergency pill can also be bought at most pharmacies. If you have had unprotected sex during your period and are concerned about pregnancy, contacting a pharmacist, GP or sexual health clinic promptly can help you understand which options remain available.