Prenatal Development Overview

Prenatal development encompasses the growth process before birth. It's divided into three primary stages: the germinal, embryonic, and fetal periods, each with unique physiological and developmental milestones.

Spanning the first two weeks post-conception, the germinal stage begins at fertilization. The zygote travels towards the uterus, dividing rapidly. Surprisingly, identical twins can form if the zygote splits in this stage.

From weeks 3 to 8, the embryo experiences organogenesis, where organs form from three primary germ layers. These layers remarkably give rise to all bodily structures, including the nervous system, during this brief but critical period.

Starting at week 9 until birth, the fetal period sees maturation and growth. The fetus develops a startle reflex by week 28. Astonishingly, by 32 weeks, it can perceive light and dark.

Maternal health and environment crucially impact development. Factors like nutrition, toxins, and stress can alter gene expression through epigenetics, influencing long-term health in ways only recently understood.

Fetuses can hear by week 24 and start recognizing voices and language. Studies suggest newborns show preferences for their mother's voice and language, indicating learning begins before birth.

The placenta is not just a life-support system; it also functions as a selective barrier. It can block certain harmful substances but also pass along antibodies, providing the fetus with early immune defense.