What is meant by a "critical period" during pregnancy? What is the importance of nutrition during a critical period?

Answer 1

A critical period is a finite period during development in which certain events occur that will have irreversible effects on later developmental stages; usually a period of rapid cell division. For example, in the last 7 months of pregnancy, the fetal period, the fetus grows 50 times heavier and 20 times longer. Critical periods of cell division and development occur in organ after organ. Most successful pregnancies last 38 to 42 weeks and produce a healthy infant weighing between 6.8 and 7.9 pounds.

Each organ and tissue type grows with its own characteristic pattern and timing. The development of each takes place only at a certain time—the critical period. Whatever nutrients and other environmental conditions are necessary during this period must be supplied on time if the organ is to reach its full potential. If the development of an organ is limited during a critical period, recovery is impossible. For example, the fetus's heart and brain are well developed at 14 weeks; the lungs, 10 weeks later. Therefore, early malnutrition impairs the heart and brain; later malnutrition impairs the lungs.

The effects of malnutrition during critical periods of pregnancy are seen in defects of the nervous system of the embryo (explained later), in the child's poor dental health, and in the adolescent's and adult's vulnerability to infections and possibly higher risks of diabetes, hypertension, stroke, or heart disease. The effects of malnutrition during critical periods are irreversible: abundant and nourishing food, consumed after the critical time, cannot remedy harm already done.