What Are Implantation Cramps?

Implantation cramps happen sometimes when a fertilized egg implants or attaches itself into the uterine lining—in other words, when you first get pregnant. Some people may get these cramps while others may not feel anything at all.

Often, implantation cramps feel similar to menstrual cramps, but they tend to be milder. They have absolutely no impact on your pregnancy or the health of your growing fetus.

Implantation cramps can easily be mistaken for menstrual cramps because they tend to occur at more or less the same time as your period (six to 10 days after the release of the egg from an ovary, known as ovulation). The cramps may be accompanied by light spotting, known as implantation bleeding.

This article describes the symptoms and causes of implantation cramps, including how they feel and how they differ from other types of cramps that can occur during pregnancy.

Causes of Implantation Cramps

It may be easier to understand the cause of implantation cramps if you understand the stages of implantation.

After ovulation and fertilization of the egg by sperm, the fertilized egg travels down a narrow tube that connects an ovary to the uterus, called the fallopian tube. The journey is brief, lasting only a few days. During this time, the egg will undergo rapid cell division and become a ball of cells known as a blastocyst.

In order for a blastocyst to develop into an embryo—the next stage of fetal development—it needs to implant into the lining of the uterus, called the endometrium. The implantation supports fetal growth by delivering oxygen and nutrients.

For implantation to occur, hormones called prostaglandins are released, which cause the blastocyst to shed its outer shell (a process known as "hatching"). This occurs one to three days after the blastocyst enters the uterus. The blastocyst then burrows into the outer layer of the endometrium.

Prostaglandins are hormones associated with pain and inflammation. It is these hormones that trigger muscle contractions in the uterus, causing cramping.

By contrast, implantation bleeding occurs when the blastocyst attaches to the wall of the uterus and breaks down some of the blood vessels within the endometrium.

Symptoms

Everyone who gets pregnant experiences implantation differently. Many notice nothing at all, while others may experience cramps, light bleeding, or both.

Common signs of implantation include:

• Cramps that feel like mild menstrual cramps (often described as "dull" and "aching")
• Prickly, tingling, or a "pulling" sensations
• Light spotting
  

The cramping can come and go but usually resolve within a couple of days.

Implantation Cramps vs. Other Cramps

Implantation isn’t the only thing that can cause cramping during pregnancy. Several situations can mimic implantation cramps, some of which may be serious. It is important, therefore, to contact your obstetrician if you ever have cramps that seem odd or unusual.

Menstrual Cramps

Since implantation often occurs around the same time as your period, it is easy to confuse implantation cramps for menstrual cramps, and vice versa.

Menstrual cramps (called dysmenorrhea) can occur in the days leading up to your period. The pain often starts one to three days before your period, peaks 24 hours after your period begins, and subsides within two to three days.

Unlike implantation cramps, the pain from menstrual cramps can be continuous rather than intermittent. It is also generally stronger, often radiating pain to the lower back and thighs. Moreover, there would be the usual amount of menstrual bleeding rather than light spotting.

Ovulation Pain

Some people experience cramps when they ovulate. This type of cramping, also known as mittelschmerz, is discernible from implantation cramping in that it occurs earlier, usually a couple of weeks before implantation. (However, if you have irregular periods, telling them apart can be difficult.)

Mittelschmerz (derived from the German word for "middle pain") is similar to implantation cramping in that the main symptoms are mild abdominal pain and spotting. The main difference (aside from the timing) is that ovulation cramps are more one-sided.

Ovulation pain is common, affecting more than 40% of menstruating people.

Early Miscarriage

A very early miscarriage, also known as a chemical pregnancy, is one that occurs before the fifth week of pregnancy. At this stage, most people don't know they are pregnant or that they've experienced a pregnancy loss. In cases like these, the bleeding is often mistaken for a regular period.

Even so, chemical pregnancies have distinctive features, including:

• Heavier than usual cramping
• Heavier than usual bleeding
• Cramping or bleeding that occurs outside of your normal period
• The sudden loss of morning sickness and other pregnancy symptoms if you are pregnant
• A pregnancy test that goes from positive to negative
  

Ectopic Pregnancy

An ectopic pregnancy is one that occurs outside of the uterus, usually in the fallopian tube. An ectopic pregnancy is a medical emergency. This is because the growing embryo can cause the fallopian tube to spontaneously rupture, leading to life-threatening blood loss.

The early signs of an ectopic pregnancy are similar to those of implantation, including cramping and bleeding. Even so, the pain and bleeding tend to be longer-lasting and worsen over time.

If your fallopian tube bursts, you can experience sudden and severe symptoms, like:

• Sharp pain in the lower abdomen on one side
• Sharp shoulder pain
• Rectal pain or pressure
• Rapid heartbeat
• Dizziness, lightheadedness, or fainting
• Nausea or vomiting
• Blurred vision
• Confusion
  

Summary

Some people experience mild cramping, known as implantation cramps, when they first become pregnant. This is caused when a fertilized egg embeds itself into the wall of the uterus. Mild bleeding, known as implantation, may also occur. These symptoms are generally short-lasting and resolve within two to three days.

Implantation cramps can mimic menstrual cramps as well as cramps that occur with ovulation or early pregnancy loss. If the cramping is sudden, severe, and accompanied by lightheadedness, vomiting, and rapid heartbeats, it may be the sign of a medical emergency known as an ectopic pregnancy.

A Word From Verywell

If you are hoping to be pregnant but haven't experienced implantation cramps, this doesn't mean you are not pregnant. Many people do not experience cramping or any other symptom during implantation.

On the other hand, if you are pregnant, the absence of cramps does not mean that the pregnancy is any more or less viable. Implantation cramping is just a symptom and does not affect your health or that of the fetus.