Child Development

The Fetal Stage

Once cell differentiation is mostly complete, the embryo enters the next stage and becomes known as a fetus. The early body systems and structures established in the embryonic stage continue to develop. The neural tube develops into the brain and spinal cord and neurons form. Sex organs begin to appear during the third month of gestation. The fetus continues to grow in both weight and length, although the majority of the physical growth occurs in the later stages of pregnancy.

Problems During Prenatal Development

Most prenatal develop occurs normally, following the established patterns with little variation. However, there are a number of things that can go wrong during this time, which are usually caused by genetics or environmental problems.

Genetic Problems

Down Syndrome - Also known as trisomy 21, Down syndrome is the most common genetic anomaly during prenatal development. Down syndrome is caused by and extra copy of the 21 chromosome (meaning there are three chromosomes instead of the usual two) and impacts approximately 1 out of every 1,000 infants. Typical features of Down syndrome include flattened facial features, heart defects, and mental retardation. The risk of having a child with Down syndrome increases with maternal age.

Inherited diseases - A number of illnesses can be inherited if one or both parents carries a gene for the disease. Examples of inherited diseases include Sickle-cell anemia, Cystic fibrosis, and Tay-Sachs disease. Genetic tests can often determine if a parent is a carrier of genes for a specific disease.

Sex-Chromosome Problems - A third type of genetic problems involves sex-chromosomes. These includes conditions such as Klinefelter's syndrome (an extra X-chromsome) and Turner syndrome (a single X-chromosome).

Environmental Problems

Harmful environmental elements that can effects the fetus are known as teratogens. There a number of teratogens that can harm the fetus, including:

Maternal Drug Use - The use of substances by the mother can have devastating consequences to the fetus. Smoking is linked to low birth weight, which can result in a weakened immune system, poor respiration, and neurological impairment. Alcohol use can lead to fetal alcohol