Few women experience their periods at exactly the same time each month. Although menstrual cycles normally range between 28 and 32 days, according to the American Pregnancy Association (APA), stress, change in routine and illness can affect cycle length in a given month. A late period combined with abdominal cramping may have several causes. A physical exam is the only way to determine the exact cause.
In most cases, menstrual periods start 12 to 16 days after ovulation, or release of an egg from the ovary, the APA reports. Cramping may signal the start of a normal period. If a woman ovulates later than normal, 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 builds up thicker than usual due to a longer-than-normal cycle, cramping may be more severe than normal.
Normal Pregnancy Implantation
Abdominal cramping and a late period could signal implantation of an embryo. Implantation normally occurs 6 to 12 days after ovulation, the APA states, but no bleeding or only very light spotting occurs. If a woman ovulates later than expected, abdominal cramping after the time of the expected period could mean implantation of the embryo in a normal pregnancy.
Abdominal cramping after a late period may indicate a potential early miscarriage. Miscarriage occurs in approximately 15 percent of pregnancies, according to California State University Long Beach (CSULB). If a miscarriage occurs just after a missed period, a woman may not realize that she was pregnant at all; she may think she just had a late, heavier than normal period, CSULB explains. Mild cramping and spotting 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, miscarriage is termed inevitable.
Ectopic pregnancy occurs when an embryo implants outside the uterus. Most ectopic pregnancies implant in the fallopian tubes, but an ectopic may also implant in the cervix. The expected period doesn't start and pregnancy hormone levels rise, but nothing is seen in the uterus on ultrasound. As the fallopian tube begins to stretch from the growing embryo, abdominal cramping on one side and then severe pain occur, according to the Mayo Clinic. Ectopic pregnancy that's close to rupture is a medical emergency that demands immediate attention, or it can be life-threatening. The fallopian tube may need surgical removal. If an ectopic pregnancy is diagnosed early enough, medication to dissolve the pregnancy and leave the tube intact may be given.