Chapter 182 Routine Prenatal Care: Second Trimester
THE CHALLENGE
Scope of the Problem: Despite the relative lack of complications that occur during the second trimester, the early signs of later problems may first appear during this phase of pregnancy. These may be missed without continued vigilance.
TACTICS
Relevant Pathophysiology: During the second trimester of gestation, levels of human chorionic gonadotropin plateau and often decline, easing many of the early maladies of pregnancy such as breast tenderness and morning sickness, although the growing uterus may now bring on heartburn and constipation. The risk of early pregnancy loss has passed (except for infrequent cases of cervical incompetence and preterm labor) and the fetus grows from being just 3 inches in length at 14 weeks to weighing roughly 2 pounds by the end of the second trimester. There is an increase in maternal blood volume and cardiac output (20% greater) to feed the needs of the growing pregnancy. The first detectable movements of the baby (quickening) occur during this trimester (generally about 16 to 20 weeks of gestation) and the female fetus has the most egg cells of any point in her life. (Oocytes peak at 6 to 7 million at about 16 to 20 weeks of gestation, declining to about 1 million at birth.) Fetal viability (ability to survive apart from the mother) begins at about 24 weeks, although intact survival at this stage is unlikely. Toward the end of this trimester maternal hemorrhoids and low back pain may occur. Colostrum (the first form of breast milk) is present by 26 weeks of gestation.
