Normal Pregnancy

Pregnant Mother

Overview of the trimesters of pregnancy

First Trimester (1st - 3rd month)

• Lasts from weeks 1 through 12 and is a critical time in the pregnancy;
• Rapid cell differentiation makes the developing embryo or fetus highly susceptible to the teratogenic effects of viruses, alcohol, cigarettes, caffeine, and other drugs;
• The woman usally experiences physical changes, such as amenorrhes (absence of menstruation), urinary frequency, nausea and vomiting (more severe in the morning or when the stomach is empty), breast swelling and tenderness, fatigue, increased vaginal secretions, and constipation;
• 7 to 10 days after conception, a serum pregnancy test can usaully detect the presence of human chorionic gonadotropin (hCG);
• A pelvic examination, performed 6 to 8 weeks later, shows uterine enlargement, Chadwick's sign, and Hegar's sign.

Second Trimester (4th - 6th month)

• Lasts from weeks 13 through 27;
• Uterine and fetal size increase substantially;
• The woman gains weight, the waistline thickens, and the abdomen enlarges;
• Reddish streaks (striations) may become apparent as abdominal skin stretches;
• Pigment changes may cause skin alterations, such as linea nigra, melasma (mask of pregnancy) and a darkening of the areola of the nipples;
• Other physical changes include diaphoresis (massive perspiration), increased salivation, indigestion, continuing constipation, hemorrhoids, nosebleeds, and some dependent edema;
• The breast become larger and heavier, and about 19 weeks after the last menses they may secrete colostrum.
• By week 20, the fetus is large enough for the mother to feel its movement (quickening).

Third Trimester (7th - 9th month)

• Lasts from weeks 28 through 40;
• The woman experiences Braxton Hicks contractions - sporadic episodes of painless uterine tightening - which help strengthen uterine muscles in preparation for labor;
• Increasing uterine size may displace pelvic and intestinal structures, causing indigestion, protrusion of the umbilicus, shortness of breath and insomnia;
• The woman's center of gravity changes; she may experience backaches beacuse she walks with a swaybacked posture to counteract the frontal weight.