Implantation bleeding vs period: key differences in timing, flow and symptoms

If you’re thinking and hoping that you’re pregnant, it can come as an unwelcome surprise to have what may appear to be the start of your period. But all is not lost! It’s possible that what you mistake for menstruation bleeding is in fact implantation bleeding, also called implantation spotting (as it’s not such a bleeding). If this is the case, far from losing heart, you can take it as a sign that your hopes are indeed about to be fulfilled. That’s why it’s important for you to be able to recognise the differences between implantation and menstrual bleeding.

In this article, we will explain what implantation bleeding is, when and why it occurs and we’ll try to answer the most common questions we encounter, such as how long does implantation bleeding last? And most importantly of all, what is implantation bleeding?

What is implantation bleeding?

Implantation spotting is a light bleed that can happen between six and twelve days after conception. Conception, the point at which egg and sperm meet and fuse into a single cell called a zygote, normally takes place in one of the fallopian tubes. Over the next few days, the zygote’s cells start to multiply as it makes its way down the fallopian tube towards the uterus. It takes six to 12 days to complete the journey, and for the cells to have multiplied to the point where they have become an embryo which is able to burrow itself into the lining of the womb. 

When it implants into the womb lining, the embryo can rupture small blood vessels. This is not dangerous, and heals spontaneously, but can cause a light bleed. This is the implantation of the embryo, the moment when pregnancy truly starts. 

Can implantation bleeding be heavy or painful?

One of the symptoms that may accompany implantation bleeding is pelvic pain. Although it doesn’t happen in every case, many people experience cramps similar to menstrual pain, with varying duration.

As for the bleeding itself, it is usually much lighter than a regular period.

This difference in intensity is one of the key signs that can help indicate whether the bleeding is related to implantation rather than menstruation.

How common is implantation bleeding?

Considered one of the earliest and easiest signs of pregnancy to detect, implantation bleeding occurs in approximately three out of ten women.

What is menstrual bleeding?

Menstrual bleeding occurs in cycles where the egg has not been fertilized. In these cases, the endometrium — the inner lining of the uterus that had thickened in preparation for a potential embryo — is shed. This inner layer is expelled through the vagina, resulting in bleeding that can last for several days.

Key differences between implantation bleeding and period 

Implantation bleeding can be mistaken for a period due to the timing within the menstrual cycle. However, there are certain differences that can help identify the type of bleeding, depending on the individual case.

Timing 

Implantation bleeding is most likely to occur about two days before your next period was due. On the other side, period bleeding can happen almost 10-12 days after ovulation, which in some cases would be the same date. This is why it is so easy to mistake for a period.

Color 

The blood from implantation bleeding is brown, pinkish or black. Normal menstrual blood is generally bright red, particularly for the first two or three days. It can be very light and sometimes consists only of a few spots.

Flow 

Implantation bleeding is very light and may consist only of irregular spotting. Menstruation usually has fairly consistent bleeding, with the flow quite heavy for the first couple of days.

Duration 

Unlike a normal period, implantation spotting is normally very brief, lasting only one or two days. This is the time it can take for the embryo to complete the process of implanting into the lining of the uterus.

In a word, implantation bleeding rarely lasts for more than one or two days, while menstrual bleeding normally lasts between three and seven days.

Cramping 

Implantation bleeding may be accompanied by very mild cramping or none at all. A normal period usually has more severe cramping, which can start a couple of days before the bleeding and continue for two or three days.

Here is a summary table of the main differences between a period and implantation bleeding:

Should you worry about implantation bleeding?

As long as the bleeding is light and stops within a couple of days, and as long as it takes place just before the due date of your next period, implantation bleeding is absolutely nothing to worry about. On the contrary, it could be the first sign that you are pregnant.

Any other bleeding during pregnancy is a different matter. Not all bleeding is a sign of something seriously wrong, but you should always seek medical advice if you have any bleeding, particularly if it is heavy and accompanied by cramps, during the course of your pregnancy.

Should you worry if you don’t have implantation bleeding?

Only about 25% of women experience implantation bleeding as one of the first signs that they are pregnant, so the chances are that you won’t have anything. The absence of implantation bleeding is therefore not a cause for concern. If you are hoping to be pregnant, or feel that you may be, you will need to rely on some other signs.

The 75% of women who do not have any implantation bleeding in early pregnancy will certainly have some other symptoms, the most important one being the well-known signal of a missed period. What are the other signs of early pregnancy?

• Changes in the breasts, with unusual tenderness, a feeling of heaviness, soreness or tingling, or a darkening of the skin around the nipple.
• Fatigue, which can start as soon as a week after conception.
• Morning sickness, which can happen at any time of day, usually consists of a feeling of nausea or actual vomiting and may be accompanied by a sudden aversion to familiar tastes and smells.
• Headaches, back pain and mood swings may also be noticed from time to time during early pregnancy

I’m having fertility treatment – will I still have implantation bleeding?

Yes, if you are one of the quarter of women who have implantation bleeding, whether the embryo arrives in your uterus via a fallopian tube, or with the help of a cannula following a cycle of IVF, it makes no difference. It still takes the same amount of time for the embryo to mature to the point where it is ready to implant, and so nothing will be different. Either way, if you are having fertility treatment, a blood test will confirm whether you are pregnant.

When to take a pregnancy test

Whether or not implantation bleeding occurs, it’s important not to take a pregnancy test too early. If you’re undergoing IVF, your specialist will tell you when to take the beta hCG blood test to confirm whether pregnancy has occurred. Keep in mind that taking a home test too soon can lead to a false positive or a false negative.

In the case of a natural pregnancy, it’s best to take a pregnancy test after you’ve been several days late for your period. This will help ensure the most accurate result.

When to repeat a pregnancy test after light bleeding

The most important thing is to identify the source of the bleeding. If you have already taken a pregnancy test, your specialist will guide you on the next steps—whether it is implantation bleeding and how many days you should wait before repeating the test.

When to consult a fertility specialist

If you are undergoing fertility treatment, consult your specialist if you have any concerns. It’s best to stay calm and seek guidance in case of any unusual symptoms.

If it turns out that the bleed you had when you were hoping to be pregnant is actually your normal period after all, don’t worry too much. Even for young and healthy adults, there is only about a 25% chance of pregnancy in any one menstrual cycle, so don’t expect instant results! We normally advise women under 35 to carry on trying for a year, or six months for women over 35, before seeking advice about fertility. However, if you have decided that it’s time to get some help, do get in touch with us at IVI. As the largest assisted reproduction group in the world, with an overall success rate of 90%, there’s a very good chance that we can help.