Implantation Bleeding vs. Menstrual Periods: Symptoms and How They Differ
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How to Distinguish Between Implantation Bleeding and Your Menstrual Period

How to Distinguish Between Implantation Bleeding and Your Menstrual Period
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Published on April 23, 2025
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Implantation bleeding is light vaginal bleeding that happens when a fertilized egg implants in the uterus. It's different from a menstrual period, which is heavier bleeding that happens for a few days in every menstrual cycle (with some variation from person to person).

It's important to recognize the difference between implantation bleeding symptoms and early pregnancy signs. That way, you can get a pregnancy test to confirm if you are pregnant, and then start prenatal care.

What Is the Menstrual Period?

The menstrual cycle prepares the body for a possible pregnancy. If no pregnancy occurs, the cycle concludes with a menstrual period, where the uterine lining sheds along with blood.

The menstrual cycle consists of four phases.

  • The Follicular Phase During this phase, one egg matures and the uterine lining (endometrium) grows and thickens in preparation for pregnancy.
  • Ovulation A follicle releases the mature egg.
  • The Luteal Phase The egg leaves the ovary and travels to the uterus. During this time, the egg will either become fertilized by sperm and implant in the uterus, or without a fertilized egg, will trigger a menstrual period.
  • The Menses Phase The uterine lining sheds, along with some blood, in a menstrual period.
The average menstrual cycle is 28 days, although everyone is different. The cycle can range from 21 to 35 days. Menstrual periods usually last between 3 and 7 days.

 Menstrual bleeding symptoms, such as cramps or bloating, can start before the actual bleeding begins.

Implantation Bleeding

Implantation bleeding is a small amount of spotting or bleeding in the very early days of pregnancy. It usually happens 10 to 14 days after conception.

 Approximately 25 percent of women experience implantation bleeding in early pregnancy, and it is not a cause for concern.

Implantation spotting happens when a fertilized egg implants in the lining of the uterus. The uterine lining has many blood vessels to nourish and support the growing fetus. As the fertilized egg implants, it can rupture some of these vessels, causing the bleeding.

 Implantation bleeding can be an early sign of pregnancy, and goes away on its own.

Implantation Bleeding vs. Periods: Key Differences

The main differences between implantation bleeding and menstrual periods are the heaviness of the bleeding and the reason for it. "Implantation bleeding is usually lighter than menstrual bleeding and occurs when a fertilized egg attaches to the uterine lining, whereas period bleeding is heavier and results from the shedding of the uterine lining," explains Sahar Wertheimer, MD, a board-certified reproductive endocrinologist at HRC Fertility in Beverly Hills, California.

These are some other differences between implantation bleeding and a period.

Implantation Bleeding
Menstrual Period
Appearance
Pink or brown
Bright or dark red
Flow
Light or spotty
Light to heavy
Timing
Within 10 to 14 days after ovulation
14 days after ovulation
Duration
A few hours to 2 days
3 to 7 days
Other symptoms
Mild cramps, headache, sore breasts, bloating, nausea, tiredness
Mild to severe cramps, tiredness, mood changes, body aches

What Other Factors Could Influence Bleeding?

Implantation and menstrual periods are not the only causes of vaginal bleeding. These are some other possible causes.

Hormonal Birth Control

Bleeding or spotting can also be caused by hormonal birth control. Doctors call this "breakthrough bleeding." Any type of hormonal birth control method, including the pill, implant, shot, patch, vaginal ring, and IUD, can cause this symptom.

Breakthrough bleeding is more common in people who take a continuous dose of hormones to skip their period, and in those who smoke cigarettes.

Stress

During stressful times, your body produces more hormones like cortisol and endorphins. These hormonal changes can make periods more erratic. Some people are late or skip periods entirely when their stress is long-term.

 Significant weight gain or loss, infection, and extreme exercise can also lead to irregular bleeding.

When should you consult a doctor about bleeding? "While occasional spotting is common, you should check in with a healthcare provider if you experience heavy or prolonged spotting outside of your normal cycle, severe cramping or pelvic pain, large blood clots, dizziness, fainting, or excessive fatigue," says Irene Woo, MD, an obstetrician and gynecologist who practices in Encino and Santa Clarita Valley, California. If you bleed during pregnancy, call your doctor right away.

When to Take a Pregnancy Test

Pregnancy tests work by detecting a hormone called human chorionic gonadotropin (HCG). The placenta makes this hormone during pregnancy to thicken the uterine lining for the growing baby.

You can take a test to confirm pregnancy as early as the first day of your missed period, but waiting will give you more reliable results. "If you're unsure, waiting at least a week after potential implantation bleeding can help ensure accuracy," says Dr. Woo. While it may be tempting to test when you're experiencing symptoms of implantation bleeding, it’s likely too early to detect a pregnancy on a home test.

Not sure which pregnancy test to choose? Check out this home pregnancy test guide.

You can learn when you ovulate and when to expect your periods by tracking your cycle. Period tracking can show you when in the cycle you're most fertile and most likely to conceive, and help you notice any changes or problems.

The Takeaway

  • Menstrual bleeding is the shedding of the uterine lining that happens every menstrual cycle when a fertilized egg doesn't implant.
  • Implantation bleeding is when a fertilized egg implants in the uterine lining during early pregnancy.
  • Other possible causes of vaginal bleeding are cysts, polyps, infections, cancer, injury to the vagina during sex, or a Pap test.
  • If you suspect implantation bleeding, take a pregnancy test a week after the bleeding starts for the most accurate results.
  • Call your doctor if bleeding is very heavy or accompanied by symptoms like severe pain or dizziness, or if you're bleeding during pregnancy.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Implantation Bleeding. Cleveland Clinic. August 9, 2024.
  2. Menstrual Cycle. Cleveland Clinic. December 9, 2022.
  3. Normal Periods. The Society of Obstetricians and Gynaecologists.
  4. Marnach M. Is Implantation Bleeding Common in Early Pregnancy? Mayo Clinic. April 19, 2022.
  5. What Your Period Says About Your Health. Northwestern Medicine. December 2021.
  6. Luteal Phase. Cleveland Clinic. November 4, 2022.
  7. Vaginal Bleeding. Cleveland Clinic. May 2, 2023.
  8. French V. What You Should Know About Breakthrough Bleeding With Birth Control. American College of Obstetricians and Gynecologists. February 2023.
  9. Sonnier S. How Stress Can Affect Your Menstrual Cycle. UT Health Houston. August 2, 2022.
  10. Irregular Periods. Cleveland Clinic. January 18, 2023.
  11. Human Chorionic Gonadotropin. Cleveland Clinic. March 11, 2022.
  12. Boynton E. Period Tracking 101: What to Know About Your Cycle. USW Medicine. November 22, 2021.
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John Paul McHugh, MD

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John Paul McHugh, MD, is an obstetrician-gynecologist and lifestyle medicine specialist in southern California. He has always placed wellness at the center of his work, in both delivering babies and improving practice standards. Dr. McHugh believes that bringing lifestyle medicine to the center of health and wellness empowers patients to make the change they seek and enjoy the benefits of true wellness.

He is a graduate of Harvard Medical School and the Massachusetts Institute of Technology and a fellow of the American College of Lifestyle Medicine. He served as a department chair at Scripps Mercy Hospital in San Diego and is now the chair-elect for the American College of Obstetricians and Gynecologists for California.

He has published several articles in the American Journal of Lifestyle Medicine and served as a peer reviewer for many articles. He contributed to the first textbook of lifestyle medicine in women's health: Improving Women's Health Across the Lifespan.

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