When Kristina Jenson*, then a mom of two, had a bit of spotting on her underwear, she assumed she was starting her period. “I kept waiting for it to come,” she says. The light spotting continued for two days, but she still hadn’t started a normal period. That’s when she realized something else might be going on: implantation bleeding. Jenson had also experienced similarly light bleeding in the first few days of her first pregnancy. “I thought, ‘Oh wait, maybe I’m pregnant,’” says the 36-year-old from Burlington, Ont. She was right: Jenson’s third child was born nine months later.
Implantation bleeding is completely normal and occurs about five to 12 days after conception, after the sperm has fertilized the egg and the newly formed embryo continues to travel down the fallopian tube and into the uterus. About a third of women experience it, says Melissa Langlais, a midwife in Halifax.
By this point, the inner lining of the uterus has already begun to thicken to support a baby—if there isn’t an embryo, it’s the shedding of this lining that becomes a period. But if there is an embryo, it attaches to this lining and, as this happens, small blood vessels in the lining can break. “This blood can go out of our uterus and then out of our vagina, and this is what is called implantation bleeding,” explains Langlais.
The blood from implantation bleeding is typically pinkish or brown, but it could also be red. It could show up as one spot on your underwear or the bleeding could last a few days. “For most women, it’s usually much lighter than a period,” says Langlais. You might also get mild cramps with implantation bleeding.
If you’re actively trying to conceive, the wait between when you think you ovulated and the expected date of your next period—often referred to as the two-week wait—can be filled with nervous excitement, and a lot of waiting and watching for signs. In fact, many people mistake implantation bleeding for their period, says Amanda Selk, an ob-gyn at Women’s College Hospital in Toronto, because the timing of the two is so close. If you track your period carefully, you would likely notice implantation bleeding a few days before the real deal would normally be scheduled to arrive. But if you’re not tracking, if your period is inconsistent to begin with, or if your normal cycle is shorter than 28 days, there’s a high likelihood for confusion.
“Some people have very light periods, in general. Some people have a little bit of spotting in the middle of their cycles anyway. And a lot of people also don’t keep track of when their periods are, so they’ll see a little bit of bleeding and say, oh, OK, that’s my period,” says Selk.
Because of this confusion, implantation bleeding can often throw off your expected due date, which is what Anita Mason* says happened to her. “I'd gone off the birth control pill about a month earlier, so I didn't have a good sense of when my next period would come,” Mason explains. She had some bleeding, and thought it was her period. Then when her next period didn’t come, she realized she was pregnant. Her original due date was calculated based on what she thought was her period, but an ultrasound eventually showed she was nearly 14 weeks pregnant, instead of only 11.
“That’s why we use ultrasound dating over period dating,” says Selk.
The good news is, implantation bleeding is nothing to worry about. In fact, for many women, it might be a joyous first sign of pregnancy. If you think you’ve experienced implantation bleeding, the best thing to do is wait a few days, and then take a pregnancy test. Good luck!
Keep up with your baby's development, get the latest parenting content and receive special offers from our partners