Implantation Cramps vs PMS Cramps: How to Tell the Difference

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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. Here’s how to tell the difference to determine whether you’ve successfully conceived.

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. While many women don’t show any signs of conception, about 30% experience implantation cramps. Sometimes implantation cramps are accompanied by light pink or brown spotting; you can also have implantation bleeding without cramps.

When Does Implantation Cramping Occur?

Not everyone experiences implantation cramping. It usually happens 10 to 14 days after ovulation – about two to seven days before your regular period is scheduled to arrive. Because of the timing, many women 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 feel similar to menstrual cramps, and they’re mild in intensity. Some women perceive light pulling, tingling, or pricking sensations.  

Where Do You Feel Implantation Cramps?

Many women detect implantation cramping in their lower abdomen and lower back. Sometimes cramps only manifest on one side of the body.  

How Long Does Implantation Cramping Last?

The duration of implantation cramping also varies from person person. Some women experience a few minor twinges, while others feel intermittent pain that comes and goes over one to three days.

What Should You Do If You Have Implantation Cramps?

If you have cramping that isn’t followed by your period, it may be related to implantation. Dr. Hou notes it might be too early take a home pregnancy test, since the hormone hCG needs to reach high enough levels for detection.

Visit a doctor if cramps are sharp and radiate throughout your pelvis and abdomen. This may signal ectopic pregnancy, which means the embryo implanted outside of the uterus. Ectopic pregnancy may also involve vaginal bleeding.