Generally, getting your period is a pretty solid indication you aren’t pregnant, but generally is not always. Bleeding during pregnancy which can be mistaken for a period while pregnant is possible, most especially in the first cycle after conception. Why?
Can you be pregnant and still have your period?
Conception that occurs close to menstruation or low progesterone levels may cause what looks like a period while pregnant.
Conception may not occur until mere days before your period is due if you have a short menstrual cycle or don’t ovulate mid-cycle.
For example, let’s say you’re regularly maintaining a 26-day cycle. Chances are you’ll ovulate around day 13. Even if you had unprotected sex on that day and sperm found egg later that day, it would still take the fertilized egg six to twelve days to reach and implant in your uterine lining.
By this timeline, your body wouldn’t know to continue producing the hormone progesterone that ceases menstruation until somewhere between day 20 to 25 of your cycle. This could leave as little as one day between implantation and projected menstruation.
If those hormone levels are insufficient, such as in a situation of low progesterone from luteal phase defect or had already begun to fall, you could have what seems like a lighter than usual period while pregnant or even one that seems entirely normal and wouldn’t think you missed a period until you were already around eight weeks pregnant.
This type of bleeding is often referred to as “break through bleeding,” and is the most common type of bleeding mistaken for a period while pregnant. Break through bleeding is usually seen during the first month of pregnancy, but may continue in the first trimester if hormone levels stay low.
It’s important to note in this case that any bleeding following the first bleed would not occur in a timely, predictable manner like a period. It would be sporadic bleeding with a varying flow. Multiple timely bleeds like a period, whether irregular/light for you or not, are very unlikely to be pregnancy bleeding.
As break through bleeding can be indicative of low progesterone, it’s a good idea to let your health care provider know about it. In fact, any bleeding during pregnancy should be evaluated. It should also be noted that even if there is bleeding when your period is due, if you are pregnant, ovulation will not occur again. This type of bleeding is not a true period while pregnant. You can’t still have what is technically referred to as a period during pregnancy, because your uterine lining is not entirely shed along with an egg.
Basal body temping can be a great way to catch such a situation, because a rise in temperature confirms ovulation and prolonged high temps for 16 days can be a way to confirm you’re pregnant, period-like bleeding or not.
Implantation bleeding may be mistaken for a period.
Many women also mistake implantation bleeding for a period while pregnant. If you followed the same example above, usually had a light period, and had spotting on day 23, you may think that spotting was your period simply a day or two early.
Bleeding varies from woman to woman, but a heavy flow is almost never implantation bleeding. You can read a full article or try our quiz on telling the difference between implantation and your period here.
Sporadic bleeding during pregnancy may be mistaken for a period while pregnant:
Finally, numerous other causes can cause bleeding during pregnancy. Some examples of causes of bleeding during pregnancy that may be mistaken for a period while pregnant include cervical changes, sex, placenta problems, carrying multiples, progesterone dips, and infection. In some cases, no reason is found and nothing is abnormal or wrong at all. This page focuses more on bleeding that typical occurs very early, before a confirmed pregnancy, you can read more in-depth on other possible causes of early pregnancy bleeding seen more frequently after a confirmed pregnancy in the first trimester here.
It’s important to understand that bleeding doesn’t guarantee that you aren’t pregnant, but then it’s usually a pretty good indication that you aren’t. Pay attention to your body, trust your instinct, and when in doubt, act pregnant until you’re sure you aren’t.
You may also find helpful:
How rare is it to be pregnant and have your period? What are the risk factors?
Missed Period Negative Pregnancy Test Explanation
Late period, missed period, irregular period, Oh, Why!?
When to Take a Pregnancy Test
Am I Pregnant? Calculating Your Chances of Pregnancy (includes a quiz)
I do my best to respond to comments within 48 hours. All comments are moderated. Please remember though, I am not a doctor nor a replacement for medical care. I can’t tell you if you are pregnant over the Internet or tell you what’s causing your spotting. I do have a medical background (medical assisting) and am a mother of four who struggled with infertility as well as multiple miscarriages. However, I am not a doctor nor claim to be one.