Prenatal Development

Prenatal Development

How can a drug cause devastating effects at one point in prenatal development but not at others?

During the earliest period of prenatal development –the stage of development from conception to birth—the fertilized egg divides, embarking on the process that will transform it in just nine months from a one-celled organism into a complex human being.

The dividing cells form  a hollow ball, which implants itself in the wall of the uterus. Two weeks after conception the cells begin to specialize: Some will form the baby’s internal organs; others will form muscles and bones; and still others will form the skin and the nervous system. No longer an undifferentiated mass of cells, the developing organism is now called an embryo.

The embryo stage ends three months after conception, when the stage of the fetus begins. At this point, although it is only 1 inch long, the fetus roughly resembles a human being, with arms and legs, a large head, and a heart that is beating and pumping blood through tiny arteries and veins.

The embryo and the fetus are nourished by an organ called the placenta. Within the placenta the mother’s blood vessels transmit substances to the embryo or fetus and carry waste products away from it. Although the mother’s blood never actually mingles with that of her unborn child, almost anything she eats, drinks, or inhales is capable of being transmitted through the placenta. If she develops an infection such as syphilis, rubella (German measles), HIV, the microorganisms involved can cross the placenta and infect the fetus, often with disastrous results. If she inhales nicotine, drinks alcohol, or uses other drugs during pregnancy, these too can cross the placenta, compromising the baby’s development (Harris and Liebert, 1991)

Even seemingly harmless over-the-counter drugs may have adverse effects on a developing embryo or fetus. For instance, a pregnant woman who takes an aspirin to alleviate a headache runs the risk of causing bleeding in her fetus. More potent drugs can do even greater harm, as we learned in the 1950’s when a drug called thalidomide, sometimes used to combat morning sickness, was found to inhibit development of an embryo’s arms and legs. More recently, the use of cocaine has taught a similar lesson. Babies whose mothers take cocaine are often born addicted, and they are often smaller and thinner than normal, prone to serious respiratory troubles and sometimes even seizures, and likely to suffer cognitive and social difficulties in childhood. (Lewis and Bendersky, 1995)

Alcohol is the drug most often abused by pregnant women, and with devastating consequences (Steinhausen, Willms, and Spohr,1993) Pregnant women who consume large amounts of alcohol risk giving birth to a child with fetal alcohol syndrome (FAS), a condition characterized by facial deformities, heart defects, stunted growth, and congnitive impairments. Even smaller amounts of alcohol can be harmful (Hunt et al., 1995)  Taking just two drinks a day during pregnancy is associated with having a child who functions more poorly than others both mentally and behaviorally (Shriver and Piersel, 1994) To be safest, pregnant women and those who are trying to become pregnant should not drink alcohol.


Please come back to read more on this subject in my next article thank you. I hope this helps you understand that drinking, drugs, smoking etc… affects not only your health but the health of your unborn child. Thank you.