What is implantation?

What is implantation? 

Implantation is when a fertilized egg cell attaches to the side of the wall of the uterus in early pregnancy. There can be physical signs of this happening (such as implantation bleeding) but most often, implantation happens without you even knowing.

When does implantation occur? 

Implantation happens very early on in pregnancy, soon after the female egg cell has been fertilized by sperm in the fallopian tubes. The fertilized egg then travels down the fallopian tubes, transforming from a single cell to a ball of multiple cells called a zygote. This zygote then implants into the uterus lining. Usually, implantation occurs eight to ten days after ovulation (when the egg cell is released from an ovary). Implantation is a process and can take several days or even weeks to complete.

Implantation symptoms: what does implantation feel like?

Many of us won’t feel anything happening around implantation. In fact, you might not realize implantation has even happened, and the first sign of pregnancy for many people will be a missed period.

However, a small number of us may experience cramps around implantation. This abdominal pain feels different to period cramps. They are described as being less intense, with a prickling, pulling or tingling sensation. This is different to ovulation pain, which happens around ovulation, preceding implantation by about a week.

Since you might not feel anything around implantation, it’s worth being aware of the other common early signs of pregnancy. These include:

• Sore or swollen breasts
• Tiredness
• Nausea and/or vomiting
• Cravings for certain foods 
• Headaches
• Constipation
• Mood swings
• Feeling faint or dizzy
• Raised body temperature

What is implantation bleeding? 

Implantation bleeding is a type of light bleeding or spotting that happens very early in a pregnancy. It's important to note that there is currently no strong scientific evidence for this phenomenon. Implantation bleeding is thought to be caused by the fertilized egg cell coming into contact with blood cells in the uterus lining as it implants into the uterine wall. 

Since implantation bleeding happens around the time your period is due, it can be tricky to tell sometimes if you’re having period bleeding or implantation bleeding.

It’s important to note that not everyone will experience implantation bleeding, and you may not get any early pregnancy symptoms at all. If your period is late and you think you might be pregnant the best thing to do is to take a pregnancy test. 

More research needs to be done into how common implantation bleeding is, but when it comes to bleeding in the first trimester, scientific research has shown it to happen in as many as 25% of pregnancies.

Implantation bleeding or period

Some symptoms of premenstrual syndrome (such as sore breasts or tiredness) are often similar to those we may experience in the first trimester of pregnancy. This can make it tricky to tell the difference, and implantation bleeding may add an extra layer of confusion since you may test negative pregnancy while experiencing this symptom. This is because the pregnancy hormones found in urine may not be high enough yet to be picked up by a test.

If you’re confused about whether or not you’re having implantation bleeding or the start of your period, you might be able to tell by monitoring your flow more closely. For instance, there are a couple of subtle differences such as the color of the bleeding and the amount that you bleed, let’s take a closer look at exactly what implantation bleeding looks like.

What does implantation bleeding look like? 

One of the ways to tell the difference between whether the bleeding you’re experiencing is implantation bleeding or menstruation is to look at the appearance of the blood itself. 

Implantation bleeding looks a little different to most menstrual bleeding, as it’s often pink or brown in color, as opposed to the bright red of menstrual blood. Check out our post on vaginal discharge colors to learn more about what implantation bleeding looks like.

As well as a change in color, implantation tends to be a form of light bleeding, meaning there’s also usually a smaller quantity of blood associated with implantation bleeding than with a steady menstrual flow. However, since the amount we bleed varies from person to person, and some of us may experience very light periods, it can make it hard to tell the two apart.

Implantation bleeding is different from other light spotting you may experience in pregnancy, or the vaginal bleeding that’s related to pregnancy loss. If you’ve tested positive for pregnancy and experience any unexpected bleeding, talk to your healthcare professional immediately. 

Keep in mind that not all bleeding in the first trimester results in miscarriage, and you can still have a healthy pregnancy with some bleeding, but it’s good to talk to a professional to rule out any pregnancy complications.

When does implantation bleeding happen?

If you do experience implantation bleeding, it’s likely to happen before your next period is due. Implantation occurs most commonly in the early phase of implantation, but you might also experience vaginal bleeding later during the process. 

How long does implantation bleeding last?

Shorter and lighter than the average period, implantation bleeding typically lasts about one to three days. Again everyone is different and this may vary between individuals. 

If you get any heavy bleeding or clotting, or have any concerns about your reproductive health, we always advise you to contact your healthcare professional. They can answer your questions and may be able to confirm if you are experiencing implantation bleeding or not.

Does everyone get implantation bleeding? 

The answer is no. While implantation bleeding is thought to be more common than implantation cramps, most women are likely to not experience any implantation symptoms at all. All of our bodies are different, so our experiences of pregnancy will vary between individuals. However, knowing our bodies better allows us to understand what is normal for us and what to look out for. Why not check out our list of things to know before planning a pregnancy for more info?

How soon should I test for pregnancy after implantation?

If you’ve experienced symptoms such as implantation bleeding and are wondering when’s the best time to take a pregnancy test, keep in mind that it might not be reliable just yet so you might not get a positive pregnancy test right away.

Pregnancy tests are most reliable from the first day of your missed period. However, some tests may be accurate four or five days before your period is due (check the manufacturer’s instructions). 

If you don’t know when your period is meant to arrive, or you have an irregular menstrual cycle, we suggest waiting three weeks after you’ve had unprotected sex before you take a test. You can purchase at-home tests in your local pharmacy or buy pregnancy tests online.

Another indication you may be pregnant is increased body temperature - this changes throughout our cycle. It rises after ovulation, and then, if we aren’t pregnant, hormones cause our body temperature to drop, causing the uterine lining to shed, prompting our period and the start of a new cycle. On the other hand, if we are pregnant, the hormone progesterone stays high, keeping our body temperature elevated. 

These changes in temperature are very small, and can be measured with a basal thermometer. As well as measuring orally with a basal thermometer, Natural Cycles users can also measure overnight with the Oura Ring or their Apple Watch.

Get to know your fertility

Thanks for taking the time to read about implantation. Whether you are interested in learning about implantation bleeding or spotting, or if you want to know the best time to take a pregnancy test, we hope you’ve learned something new! No matter where you are in your fertility journey, we can help you get to know your body better. 

Our FDA Cleared app has a mode for both planning pregnancy and a mode for natural birth control. Both options utilize the science of body temperature, and are powered by an algorithm that can predict your unique fertile window, giving you daily fertility based on where you are in your cycle.