Signs of pregnancy before a missed period may be subtle or even confusing. In fact, many symptoms go virtually unnoticed, and some are mistaken for other common ailments, such as the beginning of a stomach virus or impending menstruation. Light spotting, mild cramping, swollen or tender breasts, fatigue, nausea and headaches are among the most frequent early indicators of pregnancy. Women may experience all, or most, of these symptoms as early as two weeks after conception. Some, however, do not exhibit any signs before a missed period.
Spotting, or implantation bleeding, occurs when the embryo attaches to the uterine wall. This usually happens between one and two weeks after the egg has been fertilized. In some cases, the bleeding is barely noticeable. Other times, it may resemble the onset of monthly menstruation. Concurrently, women often experience a mild form of cramping, causing them to confuse implantation bleeding for an abnormal period.
Other frequent early signs of pregnancy include breast swelling, tenderness, increased sensitivity and even pain. The severity of the symptoms varies among women. For some, simply wearing a bra proves to be extremely uncomfortable. Others may notice only mild changes to their breasts, similar to what is experienced just before menstruation begins, making it easy to mistake pregnancy-related breast discomfort for premenstrual syndrome (PMS).
Among the most noticeable signs of pregnancy before a missed period include a lack of energy and fatigue. Daytime naps may be needed — or desired — in order to rejuvenate. Many women even go to bed hours earlier than they normally do because of excessive sleepiness. Upon awakening, pregnant women may experience morning sickness.
Nausea, with or without vomiting, is mostly due to the hormonal changes taking place within a pregnant woman's body, specifically the increase of estrogen production. Some women experience the symptom early on, whereas others are not affected until much later. There may also be a difference in the frequency and intensity of the nausea. Contrary to the term morning sickness, pregnancy-related nausea and vomiting can wax and wane throughout the day and evening hours. It is usually most prominent upon waking, however.
An aversion or sensitivity to certain smells and foods may exacerbate nausea in pregnant women as well. For example, the aroma of a particular restaurant may illicit feelings of queasiness in one pregnant woman. For another, the scent of baked goods might cause her to feel ill. Each woman's experience is usually different from the next. Whereas one woman might detest the odor of meat or fish when she is pregnant, another one might crave it.
Cravings are usually most noticeable when the desired foods are out of the ordinary. The urge to eat certain foods may stem from the body's need for a particular vitamin or nutrient. While these urges usually occur later in the first trimester, some women notice it much sooner, even before their first missed period.