Question:

I'm supposed to get my period and I haven't been this late before. Could I be pregnant? What are symptoms of early pregnancy? When should I see a doctor?

Answered by OB-GYN Karen Carlson, MD:

There are many reasons why a woman's period can be late, ranging from common hormonal imbalances to stress to pregnancy. Additionally, it is quite common to have late cycles both right after a teen begins having periods and when a woman is about to end or near menopause. A menstrual cycle is considered normal if it ranges between 21 and 35 days. Many women have times during their reproductive years when they have late or irregular periods. In fact, this is the most common reason that women seek care from a gynecologist. Stress, low or high body weight, excessive exercise, use of birth control, chronic diseases, early menopause, and other hormonal problems are just some examples that may cause periods to be late. Let's take a look at some of these in more detail. 

When we feel stressed, our body produces stress hormones from the adrenal gland. These hormones can inhibit the production of sex hormones from the ovary, which are essential to maintain regular menstrual cycles. Additionally, too much exercise, for example with long and frequent running sessions or intense weightlifting, can also decrease estrogen levels and make periods late or sometimes stop altogether. Many forms of birth control, including pills, patches, NuvaRing, progesterone IUDs, shots and arm implants, especially near the beginning of use, can make periods irregular or late. 

More concerning causes of late periods include chronic diseases and hormonal problems. Diabetes, thyroid disease, polycystic ovarian syndrome, celiac disease and pituitary tumors are common diseases and hormonal problems that can cause irregular or late menses (blood and other matter discharged from the uterus at menstruation). When periods are late, many women will have some mild symptoms similar to early pregnancy, including mild uterine cramping. The breasts may feel heavier and fuller or be tender to the touch. Nausea, constipation, mood swings, dizziness and fatigue may be experienced. These symptoms are caused by increasing levels of the hormone progesterone, and they occur in both early pregnancy and the premenstrual portion of the cycle. Because of this similarity, when a period is late for other reasons, a woman may still have some early symptoms of pregnancy, due to the higher levels of progesterone. It is reasonable to take a home urine pregnancy test with a late period to differentiate. 

Many women have a time in their reproductive years when their periods are late or irregular. It is time to call a doctor if you have a positive pregnancy test, if the abnormal bleeding pattern continues for three consecutive months, or if there is no menstrual bleeding for three months in a row.