Just because something is common, doesn’t mean it’s not scary. Case in point: implantation bleeding. Spotting during the first trimester occurs in up to a quarter of all pregnancies…and it can be terrifying! But the truth is, bleeding or spotting early in pregnancy doesn’t always mean there’s a problem. In many cases, spotting may simply be a natural sign that all is working according to plan. Here, all you need to know about early pregnancy implantation bleeding—plus how to tell the difference between implantation bleeding and your period.

What is implantation bleeding?

Implantation bleeding is the spotting that occurs after a fertilized egg travels down the fallopian tube and attaches (or implants) to the lining of your uterus. During this process, some blood vessels may break down, which can cause light bleeding. It’s also possible that the hormonal shifts associated with implantation trigger spotting—not the implantation itself.

Does implantation bleeding occur in every pregnancy?

No. Some people don’t experience any implantation bleeding—and others don’t even notice it because the bleeding is so light. For example, of moms-to-be who reported bleeding during their first trimester, about 15% noted that the episode occurred around the time of their expected menstrual period, which is when implantation occurs.

What are signs of implantation bleeding?

You may be experiencing implantation bleeding if you notice pink or brown spotting very early in your pregnancy. Implantation is pain-free and does not look like your period, which is much heavier and a brighter or darker red.

When does implantation bleeding happen?

Pregnancy is not an all-at-once occurrence. It’s a process! Here’s the basic rundown of when implantation occurs: First, fertilization usually happens within one day of ovulation. And then it takes another 6 to 7 days post-fertilization for implantation to take place. That means, it can take up to week after fertilization to experience implantation bleeding. And, to make pregnancy even more head-scratching, this early pregnancy bleeding typically happens during week four of pregnancy—or around the time you would’ve had your period.  (Your weeks of pregnancy are dated from the first day of your last period—not when your little one was actually conceived.)

How long does implantation bleeding last?

Implantation bleeding can be a brief one-off spotting, or you could experience some light bleeding for about three days. If bleeding extends longer—or is heavier—it’s important to check in with your healthcare provider asap.

How do I know if it’s implantation bleeding or my period?

Implantation bleeding is much lighter than menstrual bleeding. However, implantation bleeding can be mistaken for a light period—especially because it tends to occur around the same time you may have expected a menstrual cycle. If you misinterpret implantation bleeding for a light period, that can lead to miscalculations when you’re trying to determine your baby’s due date. The good news? A first trimester ultrasound can help recalibrate any due-date math mix-ups!

What’s the difference between bleeding and spotting?

Spotting is light bleeding. Bleeding is heavier. Another way to put it is this: For first trimester spotting, you may only notice a few drops of blood in your underwear that may or may not prompt you to grab a pantyliner. But with bleeding, you’d need a pantyliner or menstrual pad to absorb the discharge and prevent blood from soaking through your underwear. Roughly 75% of moms-to-be who dealt with first trimester bleeding experienced spotting only, according to research. The same study notes that heavy bleeding episodes are more likely to be associated with pain, longer duration, and bright red color. Meanwhile, first trimester spotting is more likely to occur in isolation, have a shorter duration, and without any discomfort or pain.

Should I call my doctor about implantation bleeding?

It’s true that some spotting is totally normal at the very early stages of pregnancy—and that in most cases it’s no indication that anything’s wronghowever, it’s always smart to tell your healthcare provider about any bleeding that occurs during your pregnancy. If you notice spotting or bleeding before you’ve had your first ultrasound, make the call sooner rather than later. First trimester spotting may indicate an ectopic pregnancy, which is a pregnancy where the fertilized egg develops outside the uterus. If left untreated, ectopic pregnancy can be life-threatening.

What else causes first trimester bleeding or spotting?

There are numerous reasons you may experience first trimester bleeding—implantation bleeding is just one of them. While many who experience early pregnancy bleeding or spotting go on to have healthy pregnancies, early pregnancy bleeding may be the first indication of a problem. That’s why it’s important to reach out to your physician or midwife if you experience vaginal bleeding at any stage of your pregnancy. Here are some reasons for first trimester pregnancy bleeding:

  • Sexual intercourse: During pregnancy, the cervix is extra sensitive, plus there’s an uptick in blood flow to the cervix, setting the stage for possible spotting after sex, a Pap test, or a pelvic exam.

  • Multiples: Bleeding is most common in the first three months of pregnancy…especially with twins.

  • Cervical changes or polyps: Sex or no sex, you sensitive cervix is more prone to light bleeding right now. In addition, a surge in estrogen can cause noncancerous cervical growths (polyps) to bleed during pregnancy.

  • Infection: Any infection of the cervix or vagina, including sexually transmitted infection can cause bleeding in the first trimester.

  • Hormonal changes: Between four and eight weeks of pregnancy, hormonal changes can cause some light bleeding. Light hormonal bleeding usually subsides around the week 13 of pregnancy. (That’s when the placenta starts producing all the hormones needed to sustain the pregnancy.)

  • Smoking: Smoking doubles your risk of abnormal bleeding during pregnancy. (Smoking in pregnancy also increases your chances of premature birth, birth defects, and Baby’s chance of Sudden Infant Death Syndrome.)

  • Miscarriage: According to research, spotting and light first trimester bleeding are not associated with a higher risk of miscarriage, though heavy bleeding is, particularly when it’s accompanied by pain.

  • Ectopic pregnancy: Here, the fertilized egg implants and grows outside the uterus and cannot result in a viable pregnancy.

  • Molar pregnancy: This is a very rare occurrence where a tissue mass grows inside the womb, not a baby.

What causes second or third trimester bleeding or spotting?

Because bleeding during the second or third trimester of pregnancy can be associated with serious issues, it’s important to reach out to your physician or midwife immediately. Later in pregnancy bleeding can be associated with the following conditions:

  • Placenta previa: This is when the placenta covers all or part of the cervix. The main sign of placenta previa is bright red (usually painless) vaginal bleeding after 20 weeks of pregnancy. At times, spotting occurs prior to more blood loss.

  • Placental abruption: Here, the placenta detaches from the wall of your uterus. This is dangerous, but rare. The most common symptom: dark red vaginal bleeding during the third trimester, accompanied by pain.

  • Preterm labor: Spotting or light bleeding can occur when labor begins earlier than 37 weeks of pregnancy. (Other preterm labor symptoms include cramps, contractions, and the rupture of membranes.)

  • Cervical insufficiency: Also called incompetent cervix, this is when the cervix dilates too early, causing premature labor.

  • Bloody show: When your cervix begins to get ready for labor it softens, thins, and widens, which brings about some light bleeding mixed with mucus. This occurs toward the end of your pregnancy. (Learn more about early labor signs.)

  • Still birth: Less than 1% of pregnancies result in stillbirth, which is when a baby dies in the womb after 20 weeks of pregnancy. Symptoms include cramps, pain, bleeding, and not being able to detect fetal movement.

More pregnancy health need-to-knows:



  • The American College of Gynecologist and Obstetricians: Bleeding During Pregnancy
  • Patterns and predictors of vaginal bleeding in the first trimester of pregnancy, Annals of Epidemiology, July 2010
  • Implantation and Establishment of Pregnancy in Human and Nonhuman Primates, Advances in Anatomy, Embryology and Cell Biology, November 2016
  • Nationwide Children’s: Bleeding During Early Pregnancy
  • Mount Sinai: Vaginal bleeding in early pregnancy
  • March of Dimes: Bleeding and Spotting From the Vagina During Pregnancy
  • MedlinePlus: Vaginal bleeding in pregnancy
  • Cleveland Clinic: Bleeding During Pregnancy
  • Hull University Teaching Hospital: Bleeding and/or Pain In Early Pregnancy
  • Centers for Disease Control and Prevention: Smoking, Pregnancy, and Babies
  • Association Between First-Trimester Vaginal Bleeding and Miscarriage, Obstetrics & Gynecology, October 2010
  • Mayo Clinic: Placenta previa
  • Children’s Hospital of Philadelphia: Bleeding in Pregnancy/Placenta Previa/Placental Abruption
  • March of Dimes: Stillbirth

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.