How to Tell the Difference Between Implantation Bleeding vs. Period Bleeding

Medically reviewed by Renita White, MD

Menstrual bleeding is typically a consistent flow that lasts about two to seven days, and may require several pad changes. Implantation bleeding tends to be more like spotting. It rarely lasts longer than three days, and is usually light enough to require a panty liner or two.

You can also tell the difference between implantation bleeding versus a period by the color of the blood. Period blood is usually crimson red, whereas implantation bleeding is typically light pink or rust-colored.

This article takes a closer look at the difference between implantation bleeding vs. period bleeding. It explains the signs of early pregnancy to look out for, and provides a list of other conditions that can cause abnormal vaginal bleeding.

Related: Your Period and the Menstrual Cycle

What Is Implantation Bleeding?

Implantation bleeding is light vaginal bleeding or spotting when a fertilized egg implants into the lining of the uterus (endometrium). It is a very early sign of pregnancy.

Each month an egg is released from the ovary and travels through the fallopian tube. When the egg becomes fertilized by sperm, it starts to divide into multiple cells. These cells travel to the uterus and implant in the endometrium. The endometrium has many blood vessels, so it is possible for bleeding to occur as the egg attaches to the lining.

Takeaway

It’s estimated that about 15% to 25% of pregnant people experience first-trimester bleeding.

How to Tell the Difference Between Implantation Bleeding and Period Bleeding

Implantation and period bleeding may appear similar, but some key differences exist. The key differences involve:

• Flow: Implantation bleeding is light. It is often only noticeable when you wipe after using the bathroom. Menstrual bleeding is heavier than implantation bleeding and may require a few pad changes each day.

• Color: The color of implantation bleeding is usually light pink or rust. Menstrual bleeding is usually bright or dark red.

• Consistency: Menstrual bleeding can be thick in consistency. Implantation is typically much lighter, more so like spotting.

• Cramping: Implantation bleeding is sometimes described as a mild prickling or tingling sensation that may be felt in the lower back, lower abdomen, or across the entire pelvic area. Period cramps last longer and are more intense, and may be stronger on one side.

• Timing: Implantation bleeding occurs around days 20 to 24 in a 28-day cycle. It is also possible to become pregnant and not experience any bleeding. Period bleeding starts on the first day of your cycle. If you notice that you are having light bleeding or spotting earlier than your period usually occurs, it could be implantation bleeding.

• Duration: Implantation bleeding may last for a few hours or a couple of days. The average menstrual period lasts two to seven days.

• Clotting: Period blood commonly produces clots as blood mixes with tissues shed from the uterine lining. Implantation does not cause uterine tissues to shed, so it's unlikely for there to be clots.
  

When to Take a Pregnancy Test

Taking a pregnancy test one week after your missed period is best for the earliest detection. Pregnancy tests detect the hormone chorionic gonadotropin (hCG). This hormone is made when the fertilized egg implants in the uterus. The production of hCG rapidly builds up each day in early pregnancy.

Will a Pregnancy Test Be Positive During Implantation Bleeding?

Implantation bleeding happens very early on in pregnancy. Because implantation bleeding happens before a missed period, a pregnancy test will likely not be able to detect the pregnancy yet. This is because the uterus does not start producing increased levels of hCG until the fertilized egg is attached to the endometrium, and the hCG level increases daily.

Related: How Period vs. Early Pregnancy Cramps Feel

Other Causes of Bleeding

Bleeding may occur in early or late in pregnancy. It may be harmless, or it could signal a serious problem. Bleeding in the first trimester happens in about 15 to 25 out of every 100 pregnancies.

In early pregnancy, an increase in blood vessels occurs in the cervix. This can raise the likelihood of light bleeding or spotting after sex or a pelvic exam.

Possible causes of vaginal bleeding during pregnancy include:

• Infection

• Early pregnancy loss

• Ectopic pregnancy

• Inflammation of the cervix

• Problem with the placenta

• Preterm labor

Aside from pregnancy-related causes, other conditions that can cause vaginal bleeding include:

• Ovulation bleeding: Spotting during ovulation is not uncommon. It's thought to be caused by hormone changes, and rarely lasts longer than one to two days.

• Polycystic ovarian syndrome (PCOS): This condition, which causes cysts in the ovaries, can interfere with normal ovulation and commonly results in irregular and unpredictable periods.

• Cervicitis: Inflammation of the cervix, known as cervicitis, can cause bleeding after sex or spotting between periods. Cervicitis is most often caused by sexually transmitted infection (STI), like chlamydia or gonorrhea.

• Pelvic inflammatory disease (PID): Untreated STIs are also a common cause of PID, a condition characterized by inflammation in the female reproductive organs. Bleeding between periods is a symptom of PID.

• Noncancerous growths: Uterine polyps and fibroids and cervical polyps are common growths in the uterus and cervix that can cause bleeding after sex and spotting between periods.

• Oral contraceptives: Breakthrough bleeding, or spotting between periods, can happen with any type of hormonal birth control, but is most common in people using low-dose and ultra-low-dose birth control pills.

• Thyroid disease: Having too much or too little thyroid hormone due to thyroid disease is known to cause irregular periods.

• Endometrial cancer: About 90% of people with endometrial cancer have abnormal vaginal bleeding, which may manifest as irregular periods or spotting between periods.

When to See a Healthcare Provider

Implantation bleeding is not serious and does not require medical care. However, it is important to alert your healthcare provider any time you experience bleeding when you are pregnant (or suspect you might be). Your provider will help you determine if your bleeding is concerning and requires medical care.

Generally speaking, it's best to contact a healthcare provider any time you have unexpected vaginal bleeding. Reach out to a provider if you experience any of the following:

• Menstrual bleeding that soaks through one or more tampons or pads every hour

• Menstrual bleeding that lasts more than seven days

• Menstrual cycles that are longer than 35 days or shorter than 21 days

• Bleeding or spotting between periods

• Bleeding after sex

• Pain in the pelvis or abdomen that is not related to your period

Summary

Implantation bleeding is light vaginal bleeding or spotting when a fertilized egg implants into the uterine lining. It often appears as a pink or rust-colored discharge. Implantation bleeding occurs around days 20 to 24 in a 28-day cycle.

Menstrual bleeding during your period is usually heavier and happens on the first day of your cycle. Period bleeding usually appears bright or dark red. To know if you are pregnant, take a pregnancy test about one week after your missed period.

Read the original article on Verywell Health.