Enormous changes occur in the body after conception. Human chorionic gonadotropin (hCG), the pregnancy hormone, increases quickly, initiating a series of events. Changes begin soon after implantation of the egg into the lining of the uterus. However, most women don't feel symptoms until approximately two weeks after her first missed menstrual period. Definitive determination of a positive pregnancy can only be determined by an accurate hCG test. However, during the first 12 weeks of pregnancy, women often experience signs indicating pregnancy. These are not considered definitive as there are can be other explanations for these changes.
Light Bleeding
Twenty percent of women experience some light bleeding around the 12th day of pregnancy. As the egg burrows into a generously blood-supplied uterine lining, its implantation may cause light bleeding. Most often, this occurs right before a woman's normal period.
Body Temperature
Women attempting to conceive may be following their basal body temperature. When body temperature is elevated it is a good indication that ovulation has occurred. If body temperature remains elevated for more than two weeks, this may be a sign of the increased metabolism caused by pregnancy. It is one of the most reliable presumptive signs of pregnancy.
Absent Menses
A noticeable sign of pregnancy is the absence of a woman's monthly menstrual period. It is one of the most common reasons women go to the physician's office with the suspicion of pregnancy. The menstrual cycle is a result of failure of increase in pregnancy-related hormones and the shedding of the uterine lining. This event does not occur due to the presence of an implanted egg. Some women experience light bleeding during the time of their normal menses. This does not rule out pregnancy.
Swollen, Tender Breasts
Immediately after conception the body begins to prepare the breast for milk production. The hormones responsible for pregnancy stimulate the glands involved in this process. Breast may become tender, swollen and firm.
Tiredness
Rapid changes in metabolism and abrupt increases hormone production causes an energy imbalance. The changes taking place in the newly pregnant body use more energy. On occasion, women may experience extreme lethargy for the first 12 weeks. Typically there's an improvement in symptoms by the second trimester.
Nausea and Vomiting
Referred to as morning sickness, pregnant women often complain of feelings of nausea and vomiting. This is a direct response to the increasing hormones that are produced by the placenta; by week six, hCG levels are more than 1,000 times their initial levels. Actually, these symptoms may occur any time, this is a misnomer, since hormones are at their peak during the morning many women associate symptoms with morning.
Constipation
Constipation may be an early symptom of pregnancy. Progesterone slows gastrointestinal smooth muscle. This delays the emptying of the intestines causing retention of stool and increased gas. This may worsen as the uterus and fetus enlarges as the pregnancy progresses, placing pressure on the bowels.
Increased Salivation
Some women experience an increase in saliva. This is a response to increased metabolism and increased hormone levels. Although this isn't a significant symptom, women find themselves putting effort into controlling the amount of saliva they produce. This tends to improve after week 14.
Increased Urination
Increased blood flow is directly related to amounts of urine production. The body increases its blood production by 50 percent causing an increase in urination that may be experienced as early as six weeks into pregnancy.
Skin Darkening
The areola, the ring around the breast, begin to darken in response to hormones. B-hCG, the pregnancy hormone released by the placenta, stimulates melanocyte production causing darkening of the skin in different areas of the body including the stomach where it produces a line from the naval to the pubis. This line is called the linea alba. These changes are typically seen around week 12.
