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What Is Implantation Window?

The implantation window is part of a key process in your journey towards pregnancy. It is the timeframe where the lining of your womb is ready for implantation to occur. 

Think of it this way: only after a fertilized egg attaches to the womb during the implantation window can you get pregnant. 

But how exactly do you identify your implantation window?

In this article, we will be covering the key events that lead to implantation including the implantation window and what happens during this process. 

What Is Implantation?

Implantation is the attachment of a fertilized egg or blastocyst to the lining of the womb. Once that happens, it gives the green light that you are pregnant. 

Experts have agreed and proven that without implantation, you can’t get pregnant. 

But don’t confuse implantation for fertilization. Successful implantation and not fertilization confirms pregnancy.  

Then, what is the implantation window? Very simple, it is the period when the uterine lining is ready for implantation to occur.

How long does implantation take?

Implantation can take place at about 6DPO-12 DPO, most commonly around 8-10 DPO. This is because there are a series of events between fertilization and implantation–when the egg attaches to the womb. Let us take you through them.  

When you have unprotected sex during your fertile window—which lingers on from four days before you ovulate, the day you ovulate, till a day after you ovulate— there is a higher chance of fertilization to occur.

Hereon, the egg begins its own journey. First, the fertilized egg goes through multiple cell divisions to become a blastocyst. 

The blastocyst travels from the fallopian tube into your uterus (which is commonly known as the womb) for implantation to take place. 

It’s important to note here that although fertilization has taken place, pregnancy is not promised because implantation has to happen first.  

While the blastocyst moves through the tube, it divides to form a special tissue called the trophoblast which surrounds the fertilized egg. This tissue helps the blastocyst to attach to the uterus and form the placenta. 

What the trophoblast does is force its way into the uterine lining. You can only imagine that the fertilized egg goes along as it is wrapped inside the trophoblast. 

The process of implantation can thus be divided into three stages – 

  • The blastocyst reaches the implantation site of the endometrium (uterine lining).
  • The trophoblast cells attach to the endometrium (uterine lining).
  • The trophoblast cells invade the endometrium (uterine lining).

The whole implantation process takes place at about 8-10 DPO. At this stage, you can be fairly sure that pregnancy has started, though you may not always see signs.

How Long Is The Window of Implantation?

The window of implantation lasts about 4-5 days and usually occurs 5-10 days after the Luteinizing hormone (LH) surge. When the blastocyst gets to the endometrium (uterine lining), it can only attach within a limited space in the cycle. This period is what we call the window of implantation. 

Now that you know when your body is ready for implantation, what are the signs that implantation has taken place?

Signs of implantation

While implantation signs may be some of the earliest indicators of pregnancy at 8-10 DPO, the only solid confirmation of pregnancy comes with a test. A pregnancy test must be taken after your first missed period. 

Though there are certain typical signs you can keep an eye out for to know if implantation has successfully occurred, you must understand that not everyone experiences these signs. 

And that’s perfectly alright! In fact, it is not very common to see people with signs that show implantation has happened.

Here are some notable symptoms of implantation:  

  • Implantation bleeding: 
    About 25% of pregnant people have reported implantation bleeding as one of their symptoms. Implantation bleeding happens when the fertilized egg attaches to the uterine lining. 
    Sometimes, it can be mistaken for a menstrual period or even a miscarriage. But unlike your monthly period, this is usually light spotting that is short-lived and disappears after a day or two.
    Read More : Implantation bleeding Vs Periods | What Does Implantation Bleeding Look Like?

  • Basal Body Temperature:
    If you track your basal body temperature (BBT) on a fertility app or calendar, a slight decrease can happen during implantation. This is also known as implantation dip and can tell you if implantation has happened or not.
    For example, a change from 96.8°F to 96.3°F (36.0°C to 35.7°C) shows an implantation dip has happened.

     

  • Cramping: 
    Implantation cramping can be felt in the lower part of your abdomen, pelvis, or your lower back area. It is in the middle of the body and doesn’t occur on one side of the abdomen as ovulation cramping does. The pain from implantation cramping could be described as a mild, dull sensation that pulls or tingles. These feelings are not long-lasting and last only for a few days before disappearing. 
    Read More : What do implantation cramps feel like?

     

  • Fatigue: 
    You may feel tired or experience a wave of fatigue after implantation has occurred. This is because the level of the pregnancy hormone progesterone elevates if conception successfully occurs, which can lead to changes in your body. This is also another reason why you become more exhausted just before the beginning of your next cycle and during early pregnancy.

     

  • Breast sensitivity and tenderness:
    Breast sensitivity and tenderness may not be prominent immediately after implantation but would occur as you approach your next expected period date. You will notice that your breasts appear larger and this is, again, due to the high levels of progesterone.

     

  • Mood swings: 
    One minute you’re happy and, the next minute you feel like wallowing in tears. Have you ever experienced this around your period? This is also due to the rise in progesterone and can occur during the implantation window as well.

     

  • Food aversions and food cravings: 
    Have you wondered why you suddenly hate your favorite dessert around your period? The spike in the progesterone levels can make you crave for weird food combinations or dislike your favorite meals.

     

  • Stomach issues:
    When implantation occurs, progesterone and other pregnancy hormones like hCG are released in higher doses. This can reduce your body’s metabolic rate, affecting your stomach and causing constipation or bloating.

Implantation and hCG (The Pregnancy Hormone)

After implantation has been confirmed, pregnancy follows. That’s the cue for your body to begin secreting higher levels of hormones like hCG from the placenta. 

The human chorionic gonadotropin (hCG) plays a crucial role in pregnancy tests. Whether it is a home urine test or a blood test, hCG levels need to be considerably high enough to confirm that you are pregnant. 

If you test positive for pregnancy, it means your body has produced significantly higher levels of hCG for the test to detect. 

Now, if you take a pregnancy test before implantation, it will read negative. This is because the hCG is produced from your baby’s developing placenta. The body can’t release this hormone if implantation has not yet taken place. 

Your pregnancy test will detect an hCG level greater than 25 mIU/mL. However, if your hCG level is less than 5 mIU/mL, your pregnancy test may read negative—which happens before implantation occurs.

Does A Successful Implantation Mean That I Am Pregnant?

The answer is a big fat yes! From what we have discussed earlier, implantation is the beginning of pregnancy. But you shouldn’t be in a hurry to test for pregnancy because it takes a while for the pregnancy hormones to be detectable in urine or blood tests. 

Even if implantation has occurred, it is still best to wait for several days before testing because the level of hCG increases progressively and may still be low immediately after implantation compared to several days after. 

So don’t panic if you test negative even after a well-timed conception. Remember, the key is to test for pregnancy at the right time. The most ideal time to take a pregnancy test is after your first missed period – this is around 14 DPO. 

Summary:

  • Implantation is the process of attaching a fertilized egg to the lining of the uterus.
  • Without implantation, pregnancy can’t take place. 
  • There is a period where implantation can successfully happen and this is called the implantation window. 
  • The implantation window is the timeframe where your body is ready to accept a fertilized egg.
  • The implantation window lasts for about 4-5 days usually around 5-10 days after the LH surge.
  • Note that a successful conception during the fertile window doesn’t confirm pregnancy.

Was this helpful?

  1. Ovulation, conception & getting pregnant. Cleveland Clinic.
  2. What are some common signs of pregnancy? https://www.nichd.nih.gov/.
  3. Sharma A, Kumar P. Understanding implantation window, a crucial phenomenon. J Hum Reprod Sci. 2012;5(1):2-6.
  4. Pitfalls in first-trimester bleeding. Emergency Medicine Clinics of North America. 2010;28(1):219-234.

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