For many women, irritability, cramps, joint pains and other signs of premenstrual syndrome are sure signs that the menstrual period is about to begin. The absence of these symptoms can often cause a woman to wonder whether she may be pregnant. Pregnancy can cause the absence of PMS symptoms, but so can other factors.
During menstruation, the uterus sheds its lining. However, the presence of an embryo inhibits this process. Lack of menstruation often is the first sign of pregnancy. A lack of other symptoms associated with menstruation, including premenstrual pain, may indicate a lack of menstruation, which in turn may result from pregnancy. Hormonal and physical changes during pregnancy can often lead to symptoms that are similar in some ways to PMS, including fatigue and nausea. If these symptoms occur, a lack of PMS is unlikely to be noticeable. Women who believe they may be pregnant should take a pregnancy test.
Significant weight loss or physical activity can also cause the menstrual cycle to miss one or more periods. Athletic amenorrhea is a known complication for many female athletes. For instance, a 1999 article in the "Journal of Clinical Endocrinology and Metabolism" collated evidence from previous research, showing that amenorrhea occurs in around 5 percent to 25 percent of female athletes. It can be treated, including by prescribing oral contraceptives to regulate hormonal activity. Chronic illnesses also can cause amenorrhea, as can some of the medication used to treat them. Similarly, drug abuse can lead to an absence of menstruation in some cases.
Even without major external causes such as heavy activity or a chronic illness, it is relatively common for a woman to miss a menstrual period from time to time. For instance, stress can cause the body to decrease production of the hormones that regulate the menstrual cycle, meaning that times of high stress can cause missed menstrual periods. However, this is less common than missing a period because of pregnancy, and a pregnancy test should be the first response. Some medications, including antipsychotics and chemotherapy drugs, can cause missed periods. Contraceptives such as birth control pills can continue to inhibit menstruation for three to six months, even after a woman has stopped taking them.
Lack of PMS Symptoms
Although missing a period typically leads to a lack of PMS symptoms, it is also possible for PMS symptoms to be absent or reduced without the loss of a menstrual period. The causes of PMS symptoms are not wholly understood, but some symptoms are linked not only to hormonal cycles but to brain chemistry, stress levels and dietary deficiencies. Changes in these factors may reduce the severity of PMS symptoms without causing a missed period.