Can a woman have periods during pregnancy? What your body is actually doing

The short answer is no. You cannot have a period while you are pregnant.

That sounds blunt, right? Especially if you’re currently staring at a spot of blood on your underwear and a positive pregnancy test on the counter. It feels like the world is glitching. But biologically speaking, the mechanics of a period and the mechanics of a pregnancy are mutually exclusive. They can't happen at the same time.

If you’re asking can a woman have periods during pregnancy, you’re likely looking for an explanation for bleeding that looks like a period. It happens more often than people realize. In fact, about 25% of women experience some form of bleeding during their first trimester. It’s scary. It’s confusing. Honestly, it’s enough to make anyone spiral into a Google rabbit hole at 3 a.m.

But here’s the science: A period happens when your egg isn't fertilized. Your hormone levels drop, the thickened lining of your uterus (the endometrium) breaks down, and it exits your body. If you're pregnant, those hormones—specifically progesterone—stay high to keep that lining intact so the embryo has a place to live. If you shed that lining, you’d be shedding the pregnancy.

So, if it’s not a period, what is it?

The "False Period" and Early Pregnancy Bleeding

The most common reason people think they're having a period while pregnant is implantation bleeding. This usually happens right around the time your period was supposed to show up. It's a classic case of bad timing. When the fertilized egg burrows into the uterine wall, it can burst tiny blood vessels.

This isn't a heavy flow. It’s usually light pink or brownish spotting. It lasts a few hours or maybe a couple of days. It doesn't require a heavy-duty pad.

💡 You might also like: Resistance Bands Workout: Why Your Gym Memberships Are Feeling Extra Expensive Lately

Then there’s the "decidual bleed." This is a bit of a medical outlier, but it’s real. Sometimes, a small part of the uterine lining sheds because the hormones haven't quite reached the levels needed to keep everything totally locked down yet. It looks like a light period. It acts like a light period. But it isn't a menstrual cycle.

According to the American College of Obstetricians and Gynecologists (ACOG), bleeding in the first trimester doesn't always mean a miscarriage is happening. It can be caused by:

• Subchorionic hematoma: This is basically a bruise or a pocket of blood that forms between the gestational sac and the uterine wall. It can cause quite a bit of bright red bleeding and even some small clots. It sounds terrifying, but many women go on to have perfectly healthy babies despite them.
• Cervical changes: Your cervix gets a massive increase in blood flow during pregnancy. It becomes "friable," which is just a fancy medical word for sensitive. If you have sex or a pelvic exam, the cervix can bleed easily.
• Infections: Sometimes a yeast infection or an STI can cause inflammation that leads to spotting.

Why the confusion persists

We’ve all heard the stories. A friend of a friend didn't know she was pregnant for six months because she "kept getting her period."

Usually, these are cases of irregular bleeding that the person interpreted as a period. If someone has a history of light or irregular cycles, they might not think twice about a bit of monthly spotting. But strictly from a physiological standpoint, the hormonal feedback loop required for ovulation and menstruation is paused the moment HCG (Human Chorionic Gonadotropin) enters the chat.

When Bleeding Signals a Real Problem

While we want to stay calm, we can't ignore the fact that bleeding can be a red flag. If the answer to can a woman have periods during pregnancy is a hard no, then the blood has to be coming from somewhere else, and sometimes that "somewhere" is a site of distress.

Ectopic Pregnancy
This is a medical emergency. It happens when the fertilized egg decides to set up shop somewhere other than the uterus—usually in a fallopian tube. As the embryo grows, it can cause the tube to rupture. The bleeding associated with this is often accompanied by sharp, one-sided pain in the abdomen or even "referred pain" in your shoulder. If you have a positive test and you're bleeding with intense pain, go to the ER. Now.

📖 Related: Core Fitness Adjustable Dumbbell Weight Set: Why These Specific Weights Are Still Topping the Charts

Miscarriage
Early pregnancy loss is devastatingly common. About 10% to 20% of known pregnancies end in miscarriage. This bleeding is usually heavy. It’s typically darker or accompanied by visible tissue or heavy cramping that feels significantly worse than a normal period.

Molar Pregnancy
This is rare, but it involves a genetic error during fertilization that leads to the growth of abnormal tissue rather than a viable fetus. It can cause bleeding that often looks like "grape-like" clusters.

The Second and Third Trimester Shift

If you’re past the 12-week mark and asking can a woman have periods during pregnancy, the stakes change. Bleeding in the second or third trimester is generally taken much more seriously by doctors than first-trimester spotting.

Placental issues are usually the culprit here.

Placenta Previa
This is when the placenta is sitting low and covering the cervix. It can cause painless, bright red bleeding. It often resolves as the uterus grows and pulls the placenta upward, but it requires close monitoring and often a "pelvic rest" order (no sex, no heavy lifting).

Placental Abruption
This is a serious condition where the placenta starts to peel away from the uterine wall before the baby is born. It causes bleeding and usually significant abdominal pain or back pain. It’s an emergency situation because the placenta is the baby’s life support.

👉 See also: Why Doing Leg Lifts on a Pull Up Bar is Harder Than You Think

Preterm Labor
Sometimes, "bloody show"—a mix of mucus and blood—happens because the cervix is starting to thin or dilate too early.

Sorting Fact from TikTok Fiction

There is a lot of misinformation on social media about "cryptic pregnancies" and people who claim they had full, heavy periods every 28 days for nine months.

While it is possible to have recurrent bleeding throughout pregnancy, it is not a period. Doctors like Dr. Jennifer Lincoln, a board-certified OB-GYN, often point out that labeling these episodes as "periods" is dangerous because it prevents people from seeking necessary medical screenings for things like placenta previa or cervical issues.

If you are bleeding enough to soak through a pad in an hour, that is never "normal" pregnancy bleeding.

Actionable Steps: What to Do Next

If you are experiencing bleeding and you know (or suspect) you are pregnant, don't just sit there wondering can a woman have periods during pregnancy. Take these steps to get clarity and stay safe.

1. Track the color and consistency. Is it pink and watery? Brown and old-looking? Bright red with clots? This information is vital for your midwife or doctor.
2. Monitor the volume. If you’re just spotting when you wipe, write down the time it happened. If you’re bleeding, count how many pads you’re going through.
3. Check for "secondary" symptoms. Are you dizzy? Do you have a fever? Is the cramping localized to one side? These are markers that help distinguish between a sensitive cervix and something like an ectopic pregnancy.
4. Call your provider. Even if it’s "just" spotting, your OB-GYN needs to know. They might want to check your HCG levels over 48 hours to ensure they are doubling, or bring you in for an early ultrasound to confirm the pregnancy is in the right place.
5. Avoid tampons. If you’re bleeding during pregnancy, stick to pads. You want to avoid introducing any bacteria into the vaginal canal, and you need to be able to see exactly how much blood is leaving your body.
6. Pelvic Rest. Until a doctor tells you otherwise, it’s usually best to hold off on sexual intercourse if you’re actively bleeding, as this can further irritate the cervix or exacerbate certain types of hematomas.

The bottom line is that while "periods" don't happen, "bleeding" does. Understanding the difference—and knowing when that bleeding moves from a minor annoyance to a medical priority—is the best way to navigate the uncertainty of those first few months. Respect your intuition. If something feels off, get it checked. Most of the time, it's just your body doing the heavy lifting of building a human, but it's always better to have a professional confirm that everything is on track.