At 20 weeks, your unborn baby weighs about 1pound and is about 19 cm long. Within a few short weeks, he/she will double in weight, and will weigh nearly 2 pounds. Head and body hair (lanugo) can now be seen. A white, greasy substance (vernix) protects the wrinkled and tender fetal skin. Your unborn baby is now completely capable of hearing, and can even hear your voice! He/she is really beginning to look like a newborn. By 24 weeks, your unborn baby has reached the earliest point for survival outside the womb.

An important fetal development occurs near the end of this stage of development. Your unborn baby's lung alveoli (tiny air sacs) have formed and the lungs begin producing surfactant. This is a substance made by the cells in the airways, and it helps keep the lung alveoli open. Surfactant production is very important for lung maturity and lung function, and will continue to increase for the remainder of pregnancy.