An unexpected trickle of blood could signal new life, or the end of this month's fertility—either way, it's important not to react immediately.
"Women are so anxious about knowing whether or not they're pregnant, they want to have definitive signs to look for, but unfortunately only time will tell," says Anuja Vyas, M.D., FACOG, with Houston Methodist Obstetrics and Gynecology Associates.
When a fertilized egg implants in the uterus, which usually happens 10 to 14 days after conception, it sometimes causes part of the uterine lining to shed, resulting in bleeding. It's one of the earliest signs of pregnancy, although the blood that's released is nearly indistinguishable from normal spotting or breakthrough bleeding that can occur mid-cycle in women who are on a birth control pill or have polycystic ovary syndrome (PCOS).
Here, experts explain how to tell the difference.
While some experts say spotting that starts off brown or wine-colored and becomes a brighter red is most likely the start of your period, George Patounakis, M.D., Ph.D., FACOG, a fertility specialist in Florida, says Googling pictures won't help.
"There's no way to tell the difference between intermenstrual bleeding and implantation bleeding just by looking," he says.
The only surefire way to know whether or not it's implantation bleeding is to take a pregnancy test, though these symptoms can offer hints that you could be experiencing implantation bleeding:
Dr. Vyas says cramping associated with implantation, while sometimes intense, doesn't typically last as long it would during a menstrual cycle. But Dr. Patounakis cautions that each woman experiences uterine contractions differently.
"A little blood inside your uterus can cause severe cramps in some women and no cramps in other women," he says. It's important to pay attention to what feels out of the ordinary for your body.
"Some women experience implantation bleeding as heavy as the first day of their menstrual cycle," says Jay M. Berman, M.D., FACOG, chief of gynecological services at Detroit Medical Center's Harper Hutzel Hospital and professor of obstetrics and gynecology at Wayne State University, "but it typically only lasts a couple of days. When it ends, the woman may feel like her period is about to start or might have breast tenderness or some nausea and may even start to feel pregnant."
Implantation bleeding can be off-and-on for a couple of days. Blood flow that's more consistent—starting off light and getting heavier as the days progress—is likely a menstrual cycle.
Any woman who's been sexually active in the previous month and could possibly be pregnant should take a pregnancy test after irregular bleeding of any kind, says Dr. Vyas.
Keep in mind that when implantation bleeding does happen, it's always before a missed period. If you experience heavy bleeding that isn't implantation or period related (after a positive pregnancy test, for example), it could be what's know as first trimester bleeding, a common bleeding that occurs in 15 to 25 percent of women early in their pregnancy. "But it might be the first sign of a pregnancy loss or even an ectopic pregnancy," a potentially fatal condition where the embryo implants outside of the uterus, says Dr. Berman.
Women who experience abnormal bleeding should see their OB/GYN or visit an emergency center immediately. "There are pregnancies that bleed early on that do just fine," says Dr. Patounakis, "but your healthcare provider needs to evaluate to make sure you're safe."