Becoming pregnant triggers many changes in your body. Some hormone levels increase while others decrease. Weight gain is inevitable and should be embraced as simply a necessary change for the developing fetus. The heart must pump harder to accommodate the increase in blood flow. All of these changes cause certain symptoms of pregnancy that are common to most women.
Changed Menstrual Cycle
One of the earliest signs of pregnancy is a delay or change in menstrual cycle. As the fertilized egg, now known as a zygote, begins to divide and move from the fallopian tube to the uterus, the cells secrete human chorionic gonadotropin (hCG). The presence of hCG signals the follicle that released the egg (the corpus luteum) to continue producing progesterone. Progesterone is a hormone that helps to maintain the blood-rich lining of the uterus, meaning the menstrual cycle will not occur as usual.
Implantation Bleeding
At this point, the group of dividing cells is known as a blastocyst. The cells on the outer side secrete enzymes that break down the blood in the lining, allowing it to attach to the uterine wall. As these blood cells break down, implantation bleeding can occur. This usually appears as spotting sometime between 6 to 12 days after fertilization of the egg, according to the American Pregnancy Association.
Breast Changes
Pregnancy triggers an increase in production of estrogen, a reproductive hormone. The estrogen signals the milk-producing glands in the breast to prepare for milk production. The glands increase in number to anticipate milk production, which results in breasts that are swollen and tender. In addition, the areolas, or skin around the nipples, may become darker in color.
Morning Sickness
The increase in hormone levels, both estrogen and progesterone, can trigger nausea and vomiting. This is likely to be felt in the morning when the stomach is empty. Eating some crackers before getting out of bed can often help alleviate this symptom.
Fatigue
Your body is continually working hard to provide the developing baby with the nutrients it needs. This puts an added strain on your body, leaving you with less energy, especially during the first trimester when the embryo is changing so rapidly.
In addition, the volume of blood in the body increases by 50 percent during pregnancy in order for the fetus to have an adequate supply, according to the Merck Manual. This increased volume has more fluid, but not necessary more red blood cells, which carry oxygen through the body. The resulting anemia can leave the cells feeling weak, resulting in fatigue.
Urinary Frequency Change
During pregnancy a woman's kidneys must work harder to process an increased volume of blood. This increase in kidney activity results in an increase in urine production. Women often need to urinate more during the night, interrupting their sleep. This is due to the fact that in an upright position, the growing fetus puts pressure on the veins that supply blood to the kidneys. In a lying position, the pressure is relieved, increasing blood flow, which increases kidney activity resulting in more urine. The uterus also puts added pressure on the bladder; making it unable to hold as much urine, increasing the frequency of urination.
