What & When Are the First Signs of Pregnancy?

Pregnancy occurs when an egg is fertilized by a sperm. After fertilization, the egg is implanted in the lining of the uterus. Once implantation occurs, hormonal surges cause a number of the early signs of pregnancy. While these signs can be uncomfortable, they are considered normal and most of them resolve once hormone levels have become more even.

Missed Menstrual Period

One of the first signs of pregnancy is a missed menstrual period. During the menstrual cycle, the lining of the uterus builds up in preparation for an egg to be fertilized and implanted. If this does not occur, the lining is shed during the menstrual period. When the egg is fertilized, resulting in pregnancy, the lining is not shed and menstruation does not occur. When the missed menstrual period occurs will depend on the length of the woman's menstrual cycle and how soon after her last period fertilization occurred.

Implantation Bleeding

Implantation bleeding is vaginal bleeding or spotting that occurs when a fertilized egg is implanted in the lining of the uterus. This type of bleeding differs from menstrual bleeding because it is lighter in color, occurs earlier than an anticipated menstrual period, and doesn't last as long as a menstrual period. It typically occurs 10 to 14 days after the egg was fertilized.

Fatigue

Fatigue is another early sign of pregnancy. The hormone known as progesterone can cause fatigue at high enough levels. During the first month of pregnancy, levels of progesterone steadily increase. Increased blood production, combined with increased levels of progesterone, can cause fatigue and a lack of energy.

Breast Swelling and Tenderness

Breast swelling and tenderness can occur as soon as two weeks after conception. Surges in hormone levels cause the breasts to feel tingly, sore or tender. They may also feel heavier or fuller as a result of increases in hormone levels.

Morning Sickness

Morning sickness can begin as early as 2 weeks after an egg has been fertilized. While the condition is called morning sickness, it can occur at any time of the day or night. Nausea is caused by the increase in estrogen that accompanies pregnancy. This causes the speed of stomach emptying to slow down and may lead to vomiting.

Urinary Frequency

Frequent urination is another early sign of pregnancy. As the fetus develops, the uterus expands to accommodate its growing size. This expansion can cause the uterus to press on the bladder and increase feelings of urinary urgency.

Mood Swings

Mood swings can occur in the first trimester of pregnancy. They are the result of rapidly increasing hormone levels in the body. These mood swings may cause a pregnant woman to become emotional or cry when she normally would not. Mood swings can last throughout an entire pregnancy.

Headaches

In the first trimester of pregnancy, headaches can occur as a result of increased blood circulation and surging hormone levels.

Constipation

Another early symptom of pregnancy is constipation. Progesterone levels surge during the first trimester, which slows down the passage of food through the intestines. The longer food stays in the intestines, the more water the colon draws from it, making the stool hard and dry. This can lead to constipation.

Food Cravings or Aversions

Food cravings and aversions are common in the first trimester of pregnancy since hormone levels rise rapidly. These hormonal surges make pregnant women very sensitive to smells, such as from foods, perfumes and chemicals. Pregnant women may also crave certain foods as a result of hormonal changes.

Increased Basal Body Temperature

Basal body temperature is the oral temperature that is taken first thing in the morning. Basal body temperature increases after ovulation and remains increased until the next menstrual period. If it remains elevated for more than two weeks, it can indicate pregnancy.