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    Implantation: What Is It? And When Does It Happen?

    Updated 05 March 2023 |
    Published 24 December 2019
    Fact Checked
    Medically reviewed by Dr. Anna Targonskaya, Obstetrician and gynecologist
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    If you’ve made the exciting decision to start trying for a baby, it’s likely you have read up on many of the different aspects of pregnancy, from morning sickness to the three trimesters and beyond. But do you know what implantation is?

    What is implantation?

    Generally speaking, “implantation” is the term used to describe when a fertilized egg attaches to your uterine lining. 

    An egg can only be fertilized when sperm successfully meets with a viable egg — this egg then travels from one of your tubes toward your uterine lining, where it attaches and begins to grow. It’s called implantation because the egg literally implants in your uterus in order to turn into a fetus.

    Implantation usually occurs about 6 to 10 days after conception, and although this might seem incredibly early, knowing some of the signs of implantation can help you determine when to take a pregnancy test to get the most accurate results.

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    When does implantation occur?

    Implantation of a fertilized egg usually occurs about 6 to 10 days after conception. In order for you to be pregnant, your embryo needs to implant successfully into the uterine lining, which has thickened for this purpose between your last period and ovulation. To find out when exactly your implantation occurred, try using our implantation calculator.

    Once implantation happens, your body releases a hormone called human chorionic gonadotropin (hCG), which produces changes in the body to support your pregnancy. Interestingly, this is the hormone pregnancy tests detect to deliver a positive result.

    Implantation: Early signs of pregnancy, from bleeding to implantation cramps

    Some women and people who menstruate are adamant that they “know” as soon as they are pregnant, particularly if they've been ovulation tracking. And it’s true that implantation does sometimes come with early signs it has taken place. Things to look out for include light bleeding and light cramps.

    The light bleeding, or spotting, that sometimes occurs is called implantation bleeding. It happens when the fertilized egg attaches to your uterine lining. Implantation bleeding is completely normal, so try not to worry if you notice it. Equally, not everyone will experience this symptom.

    Depending on your cycle, implantation bleeding often shows up around the time you’d expect to start your period, which can be a little confusing. However, implantation bleeding is lighter than typical menstrual bleeding and usually doesn’t last as long either.

    Cramps are another sign of implantation, which can happen as a result of the fertilized egg attaching to your uterine lining. Some feel these cramps in the abdomen, pelvis, or lower back, while others don’t feel any cramping at all.

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    What happens after implantation?

    It’s important to remember that every pregnancy is unique — just as every baby is different — so try not to compare your experience to others. Some of us have every common symptom of pregnancy, while others only have a few (or none at all).

    If your periods are usually as regular as clockwork, and you’ve missed your period date by a week or more, it could be an indication that implantation has taken place and you’re pregnant. 

    Remember that the first signs of pregnancy — things like tiredness, nausea, and sore or swollen breasts — appear around week six, so you won’t be able to tell if you’re pregnant right away. Taking a pregnancy test is the best way to find out.

    However, it’s worth keeping in mind that many of us have irregular menstrual cycles, in which case a missed period doesn’t necessarily indicate a pregnancy. Irregular menstrual cycles are very common and can happen for lots of reasons, including taking certain medicines or having medical conditions like polycystic ovary syndrome, eating disorders, or diabetes.

    If your period is late and you think you might be pregnant, these are some early pregnancy symptoms you can look out for:

    • Swollen and tender breasts and nipples — About one to two weeks after conception, you might experience sore breasts and tender nipples, which are a result of the hormone changes happening in your body. Breasts can also feel heavier or fuller than they did before. If this is the case, you might want to wear a looser bra or one without an underwire to feel less restricted.
    • Fatigue — Pregnancy tiredness is a common symptom that can come on as early as one week after conception, and there’s a scientific reason for it. Your body is in overdrive to produce more progesterone, which is the hormone that helps maintain your pregnancy and promotes the growth of milk-producing glands in your breasts. Incredibly, the total blood volume in your body also increases to provide nutrients to the growing fetus. So it’s not surprising you might feel worn out.
    • Headaches — The sudden increase in hormones might give you headaches while your body adjusts.
    • Nausea or/and vomiting — We’ve all heard of the dreaded morning sickness, which affects 80 percent of us during pregnancy. The term “morning sickness” is actually quite misleading because it can strike at any point of the day, not just in the morning. Waves of nausea without vomiting are also common. Both of these symptoms may begin about two to eight weeks after conception and sometimes continue throughout the pregnancy.
    • Food aversions or cravings — Developing a sudden dislike for some foods or strong cravings for others is a common pregnancy sign. Cravings and aversions can last your entire pregnancy or change throughout.
    • Mood swings — The hormonal changes that occur during pregnancy can also cause intense mood swings. They usually start a couple of weeks after conception, so give yourself some TLC if you feel a little more up and down than usual.
    • Frequent need to pee — Your blood volume increases during this period, causing your kidneys to process more fluid, which creates more urine.
    • Bloating — The hormonal changes of early pregnancy can make you feel bloated. This feeling is very similar to how you might feel at the beginning of your period.
    • Constipation — Again, thanks to ever-changing hormones, your digestive system can slow down, which can cause constipation. You can help constipation issues by ensuring you have enough fruit and fiber in your diet.
    • Nasal congestion — Feeling stuffed up? That’s thanks to increased hormones and blood volume making your nasal mucous membranes swollen and more prone to bleeding. Although most medicines can’t be used during pregnancy, non-medication saline spray and mists can give you some relief from a stuffy nose.

    Is it time to take a pregnancy test?

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    Implantation: The takeaway

    So, we’ve learned that implantation is the moment when a fertilized egg attaches to your uterine wall, typically 6 to 10 days after conception. We also now know that there can be some early signs of pregnancy to look out for, from light bleeding to sore breasts and tiredness. 

    If you’re trying for a baby and you miss a period, the first thing to do is take a pregnancy test. Regardless of the result, we’d suggest making an appointment with your health care professional. They’ll be able to confirm you’re pregnant or get to the bottom of what caused your missed or delayed period.  


    Su, Ren-Wei, and Asgerally T. Fazleabas. “Implantation and Establishment of Pregnancy in Human and Nonhuman Primates.” Adv Anat Embryol Cell Biol., 2015. NIH, Accessed Dec. 1. 

    American College of Obstetricians and Gynecologists. “How Your Fetus Grows During Pregnancy.” ACOG, Aug. 2020, Accessed Dec. 1. 

    Mayo Clinic Staff. “Symptoms of Pregnancy: What Happens First.” Mayo Clinic, 11 May 2019, Accessed Dec. 1. 

    Yvonne Butler Tobah, M.D. “Is Implantation Bleeding Normal in Early Pregnancy?” Mayo Clinic, 9 May 2019, Accessed Dec. 1. 

    Su RW., Fazleabas A.T. (2015) Implantation and Establishment of Pregnancy in Human and Nonhuman Primates. In: Geisert R., Bazer F. (eds) Regulation of Implantation and Establishment of Pregnancy in Mammals. Advances in Anatomy, Embryology and Cell Biology, vol 216. Springer, Cham. Accessed Dec. 1. 

    McParlin C, O’Donnell A, Robson SC, et al. Treatments for Hyperemesis Gravidarum and Nausea and Vomiting in Pregnancy: A Systematic Review. JAMA. 2016;316(13):1392–1401. doi:10.1001/jama.2016.14337. Accessed Dec. 1.

    History of updates

    Current version (05 March 2023)

    Medically reviewed by Dr. Anna Targonskaya, Obstetrician and gynecologist

    Published (24 December 2019)

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