First Trimester During Pregnancy

Pregnancy is generally divided into three trimesters, or three periods of 3 months each, for purposes of discussion. This is done because most women experience the same general changes during each trimester.

During pregnancy, two kinds of development go on at once—the physical changes in the mother-to-be and the physical changes in the fetus. Along with the physical changes the woman experiences, some emotional changes take place. You and your partner can use these changes as opportunities to grow, to expand your awareness of yourselves and of each other, to deepen your sense of responsibility, and to become aware of what millions of other parents-to-be have experienced.

The first trimester of pregnancy is the first 3 calendar months, or through the fourteenth week of gestation. You will experience many physical and emotional changes during this time, although most of the physical changes will be more noticeable to you than to anyone else.

Physical Changes

The major physical changes that women experience during the first trimester include the following:


For many women, a missed menstrual period is the first sign of pregnancy. Other women continue to have very light periods for the first 2 to 3 months. This lack of a regular period is due to the high levels of estrogen that the body produces to maintain the uterine lining that maintain the developing embryo.

By the time the fetus is 12 weeks old, the placenta, or afterbirth, has developed. The uterus has grown to the size of a grapefruit, with its top reaching above the pubic bone. The cervix has already begun softening.


The vagina has begun thickening and softening. It has also turned blue to violet in color as a result of the increased blood supply to the area. Vaginal secretions have become more noticeable and will increase in amount as the pregnancy progresses.


A tingling or prickling sensation is often felt in the breasts during the first of pregnancy. This is because the blood supply is increasing and the milk secreting glands are growing. After a few weeks or months, the prickling will disappear, but the breasts will usually continue to tingle until the third trimester.

During the eighth week, veins may become visible under the skin, and seated areas appear on the areola, the dark area surrounding. These elevated areas are the Montgomery glands, which secrete oil in preparation for breastfeeding.


Many women experience an increased need to urinate during the first trimester because the enlarging uterus is pressing on the bladder. This can usually eases during the second trimester, as the uterus rises out of the pelvis. Even though it means more trips to the bathroom, you should drink plenty of fluids to maintain good kidney function and to provide the water to metabolize the protein you eat.


About half of all pregnant women feel nauseated and may vomit during early pregnancy, and sometimes also in later pregnancy. This condition is called morning sickness, although it can occur at any time during the day. Morning sickness is attributed to an increase in hormone levels, a lack of vitamin B5 and/or low blood sugar. Eating foods high in B vitamins and consumption of small high-protein meals throughout the day usually help this condition.

In addition to nausea, some women also have trouble with indigestion and heartburn. The hormones relaxin and progesterone relax the smooth muscles in the body, including the sphincter at the top of the stomach, which keeps food in the stomach. Progesterone is also responsible for relaxing the intestines somewhat, thereby slowing digestion and making constipation easier. Eating a diet high in fiber (fresh fruits and vegetables, and whole tarts), drinking plenty of fluids, and exercising regularly help to minimize constipation.


The hormones of pregnancy can affect your skin either positively or negatively. Many women experience the glow of pregnancy, and their skin radiance. Others are not so fortunate and develop acne. Continue to eat a good diet and drink plenty of water. Wash your face two or three times a day with a gentle cleanser and apply moisturizer to dry areas. Avoid the temptation to pick at or squeeze the blemishes. This will only increase the likelihood of infection and scarring. Choose makeup that does not clog the pores or try limiting the time you wear it. Wash the applicators or purchase new blush brushes or powder “puffs.” If the acne is severe, you may need to see a dermatologist. Make sure that he knows you are pregnant. Two common medications used for acne, Accutane and Retin A, should not be used during pregnancy.


Pregnancy brings changes to every system in the body, and the changes require a great deal of physical and emotional energy. Properly resting is extremely important for an expectant mother. You should not feel guilty about resting during the day or about going to bed early. You need rest to adjust to pregnancy.