How to Differentiate Between Implantation Bleeding and Your Periods?

When you’re desperate to get pregnant, those two weeks between ovulation and a positive home pregnancy test (or your period) seem never-ending. Like most other women, you’ll spend them hyper-aware of every ache, twinge, and craving your body has, wondering whether it’s an early sign of pregnancy.

One of the most telltale symptoms of pregnancy is bleeding. If you do have some light spotting, does it mean anything? While it can be hard to tell, many women who go on to have healthy, normal pregnancies have what’s called implantation bleeding around the time that their embryo lodges itself into the side of the uterus.

What is implantation bleeding?

After ovulation and at the moment an egg is successfully fertilized by sperm, the embryo starts dividing and growing, sending out signals to a woman’s body to prepare for pregnancy. In turn, the walls of the uterus, called the endometrium, start to change: They’ve already been thickening throughout the menstrual cycle, but they’ll need to grow and mature even more to protect and nourish an embryo for nine months.

Anywhere from six to 12 days after fertilization, the quickly-growing embryo has moved down the Fallopian tubes to the uterus. It’s starting to need more nutrients, and the endometrium has filled in enough to support the embryo. At this stage, the embryo itself attaches to the endometrium, where it becomes dependent on a mother’s body — for the first time — for nutrients and oxygen. However, Implantation bleeding happens when the embryo makes its way into the uterus, which sometimes causes little blood vessels to burst.

When does implantation bleeding occur?

When the embryo implants into the lining of the uterus, tiny blood vessels are then disrupted in the spot it burrows into. However, this won’t cause any problems (the endometrium recovers!) but some women will experience light bleeding, from pinkish or red to brown discharge.

How long does implantation bleeding last?

This so-called implantation bleeding will likely arrive earlier than your expected monthly flow (usually around five to 10 days after conception).

How to recognize implantation bleeding

Since implantation bleeding is a symptom that can often occur before you test positive on a pregnancy test, it can be hard to know whether light bleeding is an early sign of pregnancy or just normal spotting leading up to your period. And unfortunately, there’s no conclusive way to find out.

Light bleeding after a missed period - Am I pregnant?

The best way to know whether you’re pregnant or not is to wait a few more days and take a pregnancy test. The timing of when you last had sex might also help you figure it out: If it’s been more than two weeks, it’s unlikely that any spot you're having is implantation bleeding.

What does implantation bleeding look like?

That said, approximately one-third of women who report having experienced implantation bleeding often describe it as distinct from their usual premenstrual spotting — some say the blood is darker and not as red compared with normal period blood. Others have mild cramping at the same time as the spotting. But for many women, the two types of bleeding aren’t different at all. That’s the reason it’s very tough to tell the difference between implantation bleeding vs missed period. So, you’re not alone if you assume that some spotting is implantation bleeding and get your period a few days later, or if you assume that implantation bleeding is normal spotting and end up being pregnant!

When should I see my doctor?

Light bleeding during pregnancy even at times other than implantation is often normal. Causes can include mundane things like irritation of the cervix following a pelvic exam, sex or infection of the vagina. But because sometimes bleeding following a positive pregnancy test can be a sign of ectopic pregnancy, molar pregnancy or miscarriage, you should always call your medical provider if you experience it so you can talk through any other symptoms. Don’t worry too much; chances are good that if the bleeding is light and doesn't last long, everything is fine.

References

1. Hasan R, Baird DD, Herring AH, Olshan AF, Jonsson Funk ML, Hartmann KE. (2010). Patterns and predictors of vaginal bleeding in the first trimester of pregnancy. NCBI
2. Vardhan S, Bhattacharyya TK, Kochar S, Sodhi B. (2007). Bleeding in Early Pregnancy. NCBI