Fetal Growth: Peak Development in the Second Trimester

The correct answer is the second trimester.

The largest increase in fetal growth occurs during the second trimester of pregnancy, which lasts from weeks 13 to 28. During this time, the fetus grows from a tiny embryo to a fully formed baby. The fetus's weight increases dramatically, and its organs and limbs develop rapidly. By the end of the second trimester, the fetus is about 12 inches long and weighs about 2 pounds.