What is implantation bleeding?

Implantation bleeding is light vaginal bleeding that sometimes occurs very early in pregnancy. If you choose to test as soon as you discover spotting, be aware that the earlier you test, the more likely you are to get a false negative.
Implantation bleeding is light vaginal bleeding that sometimes occurs very early in pregnancy. If you choose to test as soon as you discover spotting, be aware that the earlier you test, the more likely you are to get a false negative.

If you notice spotting or light bleeding several days before your period is due, it could be implantation bleeding. Spotting has many causes, so you might wonder how to recognize implantation bleeding. Before you reach for a pregnancy test, see if your symptoms and the timing of your spotting line up. 

Implantation bleeding is light vaginal bleeding that sometimes occurs very early in pregnancy. Implantation bleeding can happen when a fertilized egg attaches, or implants, into the uterine wall. The egg attaches to the uterus anytime between 6 to 12 days after ovulation. This means if you ovulate on day 14 of your cycle, implantation could happen sometime between 17 to 26 days after the start of your last period. 

As the fertilized egg settles into the uterine wall, this can cause the lining to slough off and result in spotting or light bleeding. Bleeding can also occur due to changing hormones related to early pregnancy.  

Even though it's rare, if you have spotting a week before your period is due, you might wonder if it's implantation bleeding. Implantation bleeding can be a very early sign that you're pregnant.

How common is spotting in early pregnancy? 

One small study showed less than one in ten women reported vaginal bleeding in early pregnancy. In most cases, the spotting occurred near the date their period was due. Spotting is even more common later in pregnancy. Up to 25% of women experience bleeding or spotting at some point during their pregnancy. 

Spotting during early pregnancy could mean many things, including:

  • changes in your cervix
  • spotting caused by sex
  • hormone imbalance 
  • infection
  • early miscarriage 

Spotting in early pregnancy can also be due to implantation.

How do I know if it's implantation bleeding?

Timing can be vital in knowing if your spotting might be implantation bleeding. Implantation typically occurs 6 to 12 days after ovulation, so spotting that happens as a result of implantation should happen in that timeframe or soon after that. For most women, this means the spotting would take place a week or just a few days before their period is due to begin. 

Implantation bleeding can vary in appearance, but it's typically:

  • light pink to brown
  • free of clots
  • a very light flow that you might only see when wiping
  • short, often only a few hours and no more than a few days 

You might have other early pregnancy symptoms, like fatigue and breast tenderness, at the time of implantation bleeding. Early pregnancy symptoms might raise your suspicions that your vaginal bleeding is due to implantation, but unfortunately, many early pregnancy symptoms are similar to premenstrual symptoms.  The best way to know if you're pregnant is to take a pregnancy test. 

When can I take a pregnancy test?

Home pregnancy tests measure the human chorionic gonadotropin (hCG) in your urine to detect pregnancy. Your body begins to produce hCG as soon as implantation occurs. The earliest you might have enough hCG in your system to get a positive pregnancy test is about eight days after ovulation. However, many pregnant women will not get a positive pregnancy test result this early.

The amount of hCG can vary due to many factors, including the timing of implantation. A week after ovulation, soon after implantation bleeding, hCG levels can be as low as 5 mUI/ML of hCG. At four weeks pregnant, at the time your period is due, your hCG levels can range from 10 to over 700 mUI/ML of hCG. Home pregnancy tests typically detect pregnancy at hCG levels greater than 20 mUI/ML.

Wanting to take a pregnancy test as soon as you experience possible implantation bleeding is understandable. If you choose to test as soon as you discover spotting, be aware that the earlier you test, the more likely you are to get a false negative. A false negative can happen when pregnant, but your hCG levels are not yet high enough to trigger a positive result on a home pregnancy test.  

The best thing to do is wait a couple of days after seeing implantation spotting before taking a pregnancy test. This gives your body time to produce detectable levels of hCG. For the most accurate results, wait until your period is due before taking a home pregnancy test.

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Medically Reviewed on 1/12/2022
References
SOURCES

American Academy of Family Physicians: "Bleeding During Pregnancy – What's Normal?"

Flo: "Period-Like Bleeding During Early Pregnancy: Is It Normal? Causes and Signs of Implantation Bleeding."

Human Reproduction: "Vaginal bleeding in very early pregnancy."

March of Dimes: "Bleeding and Spotting During Pregnancy."

StatPearls: "Human Chorionic Gonadotropin."

UCSF Health: "HCG blood test – quantitative."

UT Southwestern Medical Center: "How early can home pregnancy tests show positive results?"