How to Tell the Difference Between Implantation Cramps and PMS Cramps

It’s easy to confuse implantation cramps with normal menstrual cramps. Learn about the differences to figure out if you’re experiencing early signs of conception.  

It's a few days before your period, and you feel mild cramping in your lower abdomen. If you're trying to get pregnant, the twinges may leave you wondering if you're experiencing PMS or implantation symptoms. It can be challenging to tell the difference. However, there are some key ways to distinguish between them. Here's how to tell if you're about to get your period or you've successfully conceived.

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What Are Implantation Cramps?

Implantation occurs when a fertilized egg attaches to the uterine lining, signaling the start of a pregnancy, says Jingwen Hou, M.D., Ph.D., an OB-GYN specializing in reproductive endocrinology and infertility at Kaiser Permanente in Hawaii. And this implantation can cause some abdominal cramping, which can feel like a twinge of discomfort or even mild period cramps.

While many people don't experience any noticeable signs of implantation, about 30% report experiencing some implantation cramps. Sometimes, implantation cramps are accompanied by light pink or brown spotting, but you can also have implantation bleeding without cramps.

When Does Implantation Cramping Occur?

Not everyone experiences implantation cramping. If you do notice it, the cramping usually happens anywhere from 3 to 10 days after ovulation—about two to nine days before your regular period is scheduled to arrive. Because of the timing, many people mistake implantation cramps for PMS. "It can be difficult to tell if you're having your period or if it's a sign of very early pregnancy because of the timing of it, and you may experience cramps for both," says Dr. Hou.

What Do Implantation Cramps Feel Like?

Implantation cramps can feel very similar to menstrual cramps. But while some people experience moderate to severe cramping with their period, implantation cramps tend to be much milder in intensity. Some people perceive light pulling, tingling, or prickling sensations with implantation cramping.

Where Do You Feel Implantation Cramps?

Not everyone feels cramping during implantation. However, for those who do, they're usually felt in the same location as menstrual cramps. Many people detect implantation cramping in their lower abdomen or lower back. Sometimes, implantation cramps only manifest on one side of the body.

How Long Does Implantation Cramping Last?

The duration of implantation cramping varies from person to person but doesn't last longer than a few days. Some people experience a few minor twinges over a few hours or the course of a day. On the other end of the spectrum, some experience intermittent cramping that comes and goes over one to three days.

What's Next If You Have Implantation Cramps?

If you have cramping that isn't followed by your period, it may be related to implantation. If you think you may be pregnant, it's wise to take a pregnancy test. However, you may still want to wait to test.

Dr. Hou notes that at the time of implantation cramping, it's likely still too early to get an accurate result from a home pregnancy test. Home pregnancy tests work by detecting human chorionic gonadotropin (hCG) in urine, and the hCG in your body needs to reach high enough levels to be picked up by the test. Home pregnancy tests are most accurate if taken after a missed period but may detect pregnancy sooner (some as early as 10 days after conception).

Visit a doctor if cramps are sharp and radiate throughout your pelvis and abdomen. This may signal ectopic pregnancy, which means the embryo is implanted outside of the uterus. Ectopic pregnancy may also involve vaginal bleeding, shoulder pain, dizziness, and weakness. This type of pregnancy is not viable and can become a life-threatening emergency for the pregnant person if it goes untreated.

The Bottom Line

Distinguishing between implantation cramping and menstrual cramps can be challenging. However, if you don't normally experience menstrual cramps, your cramps feel different than normal, or your period doesn't come as expected, you might be experiencing implantation cramping. Once your period is late, take a test to be sure.

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