Beginning at the Beginning:
Understanding the Biological Basis for FAS
© 1996-2002 Deb Evensen

Sperm

Everyday a healthy young male body produces nearly 100 million sperm. Each sperm contains an entirely unique selection of the father-to-be’s genetic material. At each ejaculation, approximately 500 million mobile sperm are dispatched. Almost half of the sperm of a healthy young man have small defects that prevent them from fertilizing an ovum. Recent research has implicated alcohol and other drug’s impact on the sperm.

Ovum

Females store approximately 500,000 eggs, but most of them never fully ripen, and gradually degenerate. In the course of a woman’s life, ovulation occurs about 400 times. Research is just beginning to address the possible effects of alcohol and other drugs on stored ovum.

Pre-fertilization

Research has shown that alcohol consumed by the male months before conception can produce defective sperm. The male cannot cause FAS, but other birth defects can be present due to the defective sperm. Cocaine can also bind to sperm before and after ejaculation, exposing the baby at the time of conception. If only the mother is ingesting cocaine, the sperm can pick up the drug in her body and attach.

Fertilization

When a sperm has been successful in penetrating the ovum wall and then the inner cell membrane, a chemical signal goes out from the ovum’s inner membrane to the wall, which becomes impenetrable to other sperm. Even those that are halfway in a are shut out. More than one set of chromosomes would be a disaster for the ovum. The issue to consider: how many times does conception take place during the use of alcohol.

Once the tail has served its purpose it separates from the head. The tail is a jelly-like substance that helps maneuver the sperm up the fallopian tube to penetrate the female egg.

Fusion

At 20 hours after fertilization the moment of fusion is at hand. The head of the sperm with its genetic material has penetrated the ovum’s cell plasma and is steadily approaching the egg’s genetic materials which are stored in the nucleus deep inside the ovum. Both nuclei are drawn toward each other and soon fuse. Instantaneously, numerous hereditary characteristics of the new individual are determined.

Cell Division

30 hours after fertilization, the first cell division take place. There are now 2 cells, each containing genes from both the mother and the father. Cells divide anew every 12-15 hours. There is a blue halo around the cell division with a transparent shield inside of that. Years ago it was thought that this the shield would filter out harmful substances from getting inside the cell, much as we thought the placenta did. We now know that harmful substances freely pass across the shield and also the placenta.

Blastocyst

Comprising about a hundred cells, the blastocyst passes through the narrowest portions of the fallopian tube and enters the uterus. The blastocyst then travels down the uterus, bounces, takes several days to decide, and then finds a place to implant.

Implantation

Eight days after fertilization (and most often before a woman knows she is pregnant) the blastocyst has selected a suitable site for attachment and implantation. Usually it becomes embedded near the "ceiling" of the uterus. Once implantation has taken place, an intensive chemical exchange of information between it and the mother’s body begins. Proteins, such as hormones formed in the blastocyst, enter the woman’s bloodstream, often causing nausea or morning sickness. From that point on, whatever enters the woman’s bloodstream also enters the baby’s bloodstream.

Teratogens

Teratogen is the term we use to describe anything in the environment that negatively impacts fetal development upon ingestion by the mother. The time period for the negative impact is called its window of exposure or opportunity. Thalidomide (medication formerly prescribed to pregnant women for morning sickness) is an example of a teratogen with a window of exposure of 31/2- 5 weeks of gestation, so the damage occurred to the developing limbs. The window of exposure for alcohol is the entire 9 months of pregnancy.

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The window of exposure for alcohol is the entire 9 months of pregnancy. Whatever is developing, at the time of exposure to the fetus, can be affected.

For example:

at five weeks:

The fetus is approximately 1/2 inch long. The eyes, nose, and mouth are beginning to show. Human growth takes place from the head downward. Therefore, the head develops much more rapidly than the rest of the body; however, it also take more time to develop because of its complexity. Development of the head will continue long after birth. The arms and legs are extremely short at this time, but the hands and feet are starting to take shape, and the fingers are starting to form, but are still very webbed.

eye development:

At 6 1/2 weeks the iris and pupil are developing, but the eyelid has not yet formed. As the eye (a complex system of muscles and nerves) takes several weeks to develop, exposure to alcohol can result in a number of muscle and vision problems.

at eight weeks:

At 8 weeks of gestation, the 1-1/2 inch long fetus still has a great deal of development ahead. The brain develops throughout gestation. Any time a woman drinks, it can influence how her baby’s brain develops.

If alcohol is present in the mother’s body, it will cross the placenta into the fetus’s body. While waiting for the alcohol to go back to the mother’s body for processing, the fetus will excrete the alcohol into the amniotic fluid and re-ingest it many times. The blood alcohol content of the fetus will be the same as the mothers - for at least twice as long!

finger development:

At 11 weeks the fingers are forming. Alcohol can impact the development of the joints and the placement of the fingers on the hand. Cocaine is a vasoconstrictor, so if the blood is unable to flow properly to the fingers, they will not obtain normal length. In some case, when a pregnant woman uses cocaine, the 3rd section of a finger may not form at all.

at 13 weeks:

At 13 weeks of gestation the eye is well developed and the lids close for several months, and the nose is short in comparison to a newborn (much of the additional growth in length occurs after birth). A picture of the fetus at this point would show how alcohol slows facial development resulting in typical FAS characteristics.

at 17 weeks:

By week 17 of gestation, the fingers and fingernails are formed, as are the creases in the palm of the hand, normally formed by the fetus opening and closing the hand repeatedly. A drunk fetus won’t move as often, and this contributes to the creases not forming properly.

Summary
Anytime after implantation of the blastocyst, when a woman drinks alcohol, it crosses the placenta into the baby’s body and has the potential to damage whatever is developing at the time in the fetus. The amount of damage depends on many factors. However, alcohol is a teratogen more damaging to the fetus than crack cocaine, than heroin, than marijuana.

Women want to be good mothers. They want to give birth to healthy babies, even if giving the baby up for adoption. No woman purposely drinks in order to intentionally give birth to a child with brain damage! An integral part of the disease of alcoholism is denial. If a woman is pregnant and drinking, she needs help and support. Anytime a woman stops drinking during pregnancy, her baby will be healthier than if she continues consuming alcohol.

References:

Colin Rose, Accelerated Learning, Bantam Doubleday, Dell Publishing Group, 1997.

Ann Streissguth, Fetal Alcohol Syndrome: A Guide for Families and Communities, Paul H. Brookes Publishing Co., Baltimore, MD, 1997.

Robin Karr-Morse and Meredith S. Wiley, Ghosts from the Nursery: Tracing the Roots of Violence, The Atlantic Monthly Press, New York, NY, 1997.

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