Think you don't need to use protection if you have sex on your period? As it turns out, that's not entirely true. "It's technically possible to get pregnant while on your period, but it's rare for this to happen," says Barbara Stegmann, M.D., a triple board-certified OB-GYN and women's health clinical lead at Organon. Keep reading to learn why it's possible to conceive by having sex during menstruation.
Understanding Your Menstrual Cycle
For starters, it helps understand your menstrual cycle. "A period is defined as the blood loss that happens at the end of an ovulatory cycle, as the result of an egg not being fertilized by a sperm," explains Michele Hakakha, M.D., a board-certified obstetrician and gynecologist based in Los Angeles and co-author of Expecting 411: Clear Answers and Smart Advice for Your Pregnancy.
"Every month, a woman releases an egg on approximately day 14 of her cycle," says Dr. Hakakha—though ovulation date varies for everyone, and it's also possible to have irregular cycles. "Prior to the release of the egg, the hormones in a woman's body increase to prepare (and thicken) the lining of the uterus in case the egg is fertilized and a pregnancy occurs. If there is no fertilization, the lining of the uterus is sloughed off about 14 days later. This is called your period." Most people have periods that last from two days to eight days and take place every 26 to 34 days.
Ovulation typically occurs midway through the cycle, and it's the most fertile time in your menstrual cycle—meaning when you're most likely to conceive. Because sperm can survive for several days in the reproductive tract, a woman can get pregnant by having sex during ovulation or the days leading up to it.
Can You Get Pregnant During Your Period?
Most people have menstrual cycles that last 26 to 34 days, and if someone with this cycle has an average two- to eight-day period, they will probably not get pregnant during their period. An egg that is released during ovulation but remains unfertilized "comes out with all of the menstrual blood," Dr. Hakakha explains.
That said, the chance of pregnancy on your period increases if you have an irregular cycle. "A woman with a shorter menstrual cycle (24 days, for example), could have seven days of bleeding, have intercourse on her final day of bleeding, and ovulate three days later," Dr. Hakakha says. "Since sperm live for three to five days, she could definitely get pregnant" if it fertilizes a released egg, which has a lifespan of about 24 hours.
In addition, some women experience breakthrough spotting or bleeding between periods. This can occur during ovulation and be mistaken for a period, making it difficult to establish the exact place in the menstrual cycle. Having sex during ovulation increases your chances of getting pregnant.
The Bottom Line
"Unprotected intercourse can result in pregnancy if the sperm and egg can get together and you are off in your timing estimates," says Lauren Sundheimer, M.D., MS, FACOG, an OB-GYN practicing in Orange County, California. "If you are able to track your fertile window, then having intercourse outside of when you are considered fertile or when you are nearing ovulation might be safe, but there is never a guarantee that you will not get pregnant."
by Sophie Bell |
It’s possible, but unlikely. To conceive while on your period, you’d have to have a very short menstrual cycle. This would bring the time of ovulation closer to the time when you are bleeding, especially if your period tends to last a long time, with bleeding for up to 10 days.
Ovulation, (when the egg is released from the ovary), usually happens about 14 days before your next period. So if you have a 28-day cycle, you’ll usually ovulate sometime between day 10 and day 15 of your cycle. The first day of your period (when you start bleeding) is counted as the first day of your menstrual cycle.
During your period, an egg is usually developing in preparation for release mid-cycle. The time that it takes for an egg to mature within the ovary can vary. This means that the day you ovulate can also vary from cycle to cycle, but is usually 14 days before your next period starts.
Having a short cycle and a longer period could increase your likelihood of getting pregnant just after your period. For example, if your cycle is shorter than average, around 22 days, then you could ovulate just days after your period, if your period lasted seven days or more.
It’s also worth remembering that sperm can survive inside a woman’s body for up to seven days, so if you have sex during your period and ovulate up to seven days later, there is a possibility of getting pregnant.
It’s also possible to mistake breakthrough bleeding, or spotting between your periods, for a regular period. This bleeding could happen during your fertile time. If you are experiencing bleeding between your periods, you should tell your GP.
Some women use ovulation kits to pinpoint their most fertile time. Most of these kits test for the peak of luteinising hormone, or LH, which is the trigger for egg release. You could use these to find out when you are most fertile during your cycle.
Learn how to identify when the best time to get pregnant is.
Sophie Bell is an editor at BabyCentre. She updates and creates health content and is responsible for email newsletters.