During pregnancy, a woman's body goes through many physiological changes, and these are often passed along to the fetus via the placenta. Almost anything a woman puts into her body during pregnancy -- nutrients, drugs, alcohol, medications, etc. -- can find its way into the fetus and may have an adverse effect on its development. The nutritional requirements of a woman change when she is pregnant for she is now eating for two (or more in the case of multiple births), and eating a nutritionally balanced diet sufficient to support the developing fetus(es) is important. This will be discussed below.
There has been much publicity about the effects of drugs and alcohol on the fetus: so-called "crack" babies and babies born with fetal alcohol syndrome, for example. It is known that drugs and alcohol have effects on the development of the fetus, and particularly on the developing brain and nervous system. Medications prescribed by doctors and over-the-counter medications can also affect a fetus, and this paper will discuss the effects of alcohol, legal and illegal drugs on fetal development. Smoking during pregnancy usually results in low birth weight babies, and it has other deleterious effects which will also be discussed. Not everything which can affect a fetus has been covered in this paper, but it will become obvious from the evidence presented below that a mother's behavior has serious effects on the health of her fetus.
When a woman is pregnant, she undergoes a series of continuous, small, physiological adjustments that affect the metabolism of the nutrients she takes in (1). For instance, by the second quarter of pregnancy, changes have taken place in protein metabolism, and during the last quarter, when the demands of the fetus are greatest, these adjustments allow a positive nitrogen retention. The adjustments in metabolism are affected by the size of the baby, maternal food intake, physical activity of the mother, an...