What Are the Causes of Abdominal Cramping & Period Lateness?

Few women experience their periods at exactly the same time each month.

Although menstrual cycles normally range between 21 and 35 days, stress, illness and change in routine can affect cycle length in a given month.

A late period combined with abdominal cramping may occur for several reasons. A physical exam by your doctor is the only way to determine the exact cause.

Late Ovulation

Menstrual periods usually start 12 to 16 days after the release of an egg from an ovary, known as ovulation. Cramping may signal the start of a normal period.

If a woman ovulates later than usual, abdominal cramping after she expects her period to start may mean nothing more than the occurrence of an extra long menstrual cycle. If the uterine lining becomes thicker than usual because of the longer-than-normal cycle, bleeding and cramping may be more severe than normal.

Normal Pregnancy Implantation

Woman holding her belly in bed

Causes of Bleeding at the Time of Period When Pregnant

Learn More

Abdominal cramping and a late period could signal implantation of an embryo during a normal pregnancy. Implantation usually occurs 6 to 12 days after ovulation, before the expected next period. Implantation often goes unnoticed but sometimes causes very mild bleeding and cramping.

When a woman ovulates later than expected, implantation may also be delayed. If abdominal cramping and bleeding occur with this implantation, this may seem like a late period with cramping.

Early Miscarriage

Abdominal cramping with a late period may sometimes indicate an early miscarriage. Miscarriage occurs in approximately 10 percent of all pregnancies, according to the American College of Obstetricians and Gynecologists. If a miscarriage occurs just after a missed period, a woman may not realize that she was pregnant at all; she may think that she just had a late, heavier-than-normal period.

Mild cramping with a small amount of bleeding is sometimes called a threatened miscarriage, which may or may not progress to a complete miscarriage. If cramping increases, the cervix dilates and bleeding starts, leading to an inevitable miscarriage.

Ectopic Pregnancy

Woman holding her belly in bed

Causes of Light Bleeding During the First Month of Pregnancy

Learn More

Ectopic pregnancy occurs when an embryo implants outside the uterus. Most ectopic pregnancies implant in a fallopian tube.

With an ectopic pregnancy, the menstrual period does not occur when expected and a pregnancy test may be positive -- but nothing is seen inside the uterus on an ultrasound. As the fallopian tube begins to stretch from the growing embryo, abdominal cramping begins on that side. The tube will eventually rupture, causing severe abdominal pain and internal bleeding.

An ectopic pregnancy requires prompt medical attention.

If it is diagnosed early enough, a medication called methotrexate may be used to dissolve the pregnancy and leave the tube intact. If the fallopian tube ruptures, emergency surgery will be necessary.

Seeking Medical Attention

Contact your doctor to help determine the cause if you have a late period with cramping. Seek prompt medical attention if you have severe pain or a lot of bleeding, such as soaking a sanitary pad in an hour or less. Also obtain prompt medical care if your bleeding and cramping are accompanied by vomiting, lightheadedness or weakness.

Reviewed by: Mary D. Daley, MD