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Can drinking alcohol harm the child before the mother knows she is pregnant?

chalkboard newborn

Photo credit goes to: Cute moments photography

These days pregnant “moms to be” have lots of things to worry about, from second hand smoke to the chemicals in their make-up. Well they can unfortunately add one more thing to that list, a new study finds that alcohol drunk by a mouse in early pregnancy changes the way genes function in the brains of the offspring. The early exposure was also later apparent in the brain structure of the adult offspring. The timing of the exposure corresponds to the human gestational weeks 3-6 in terms of fetal development.

In addition, the exposure to alcohol was found to cause similar changes to gene function in other tissues of the infant mice. These results suggest that alcohol causes permanent changes to gene regulation in the first cells of developing embryo.

Exposure to alcohol during pregnancy may damage the child in many different ways, including learning disabilities as well as congenital deformities. The mechanisms through which alcohol impacts fetal development are not yet fully understood, and diagnosing the damage caused to the child is difficult.

In the mouse model where the dam drinks alcohol in early pregnancy, the offspring exhibit symptoms similar to fetal alcohol syndrome (FAS) in humans: decreased growth rate, similar structural changes to corresponding areas of the face and scull, and hyperactivity. The early exposure begins at conception and continues until the nervous system begins to develop. In humans, this corresponds to the first three or four weeks after conception in terms of development – a period during which the mother-to-be is often unaware of being pregnant.

Early pregnancy is an active time for cell division and differentiation. All the different cell types share a similar DNA strand, but in each of them a unique epigenome is formed to regulate their gene function. At this stage, the embryo is vulnerable to external influences, and any changes can spread extensively to different tissues as cells divide.

The study wanted to determine whether alcohol consumed in early pregnancy causes changes to the epigenome that regulates the embryo’s genes. In addition, the researchers examined whether the potential changes would be seen later in the gene function and brain structure of the offspring.

The research focused on the hippocampus, a brain structure important for memory and learning. It is known to be particularly sensitive to alcohol. In the study, early exposure to alcohol changed the epigenome as well as the function of several genes in the hippocampi of infant mice. Alcohol-induced changes were also seen in the brain structures of the adult offspring: the hippocampi, olfactory bulbs and cerebral ventricles.

In addition to the hippocampus, alcohol caused similar changes to gene function in two different tissues of the infant mice – bone marrow and the olfactory epithelium of the snout.

“The results support our assumption that alcohol permanently alters gene regulation at a very early stage,” states Dr. Nina Kaminen-Ahola, lead researcher.

“This would be significant for the challenging diagnostics of alcohol-induced damage. The mechanisms and biological markers which can aid in diagnosis are studied so that we can offer the developmental support necessitated by the damage as early as possible.”

“Ideally, a swipe sample from inside the mouth of a newborn could reveal the extent of damage caused by early pregnancy alcohol exposure,” she continues.

Heidi Marjonen, Alejandra Sierra, Anna Nyman, Vladimir Rogojin, Olli Gröhn, Anni-Maija Linden, Sampsa Hautaniemi, & Nina Kaminen-Ahola (2015). Early Maternal Alcohol Consumption Alters Hippocampal DNA Methylation, Gene Expression and Volume in a Mouse Model PLOS ONE : 10.1371/journal.pone.0124931


4 responses

  1. Tiffani Lintzenich

    I have a question. Did the research study say how much alcohol it took to cause this effect, or can one drink cause this much damage to an infant?

    May 15, 2015 at 6:22 am

    • I wouldn’t say this much damage per say. Think of it more as starting off on the wrong foot, genes that should be active aren’t and vice versa. The long term effects it has on a child growing up is unknown, however we have seen the effect of it in our own society indirectly.

      This was a mouse study, so while it is quite telling it is hard to convert to a human model how much alcohol was involved is hard to calculate without looking at other factors like the difference in metabolism between a mouse and a human.

      I can tell you the mice drank (as they please) from a 10% alcohol by volume solution for just the first 8 days of gestation. The typical beer has anywhere from about 4-14% alcohol by volume. Also the gestation period of a mouse is typically about 20 days so adjusting for the differences between humans and mice that would be equivalent to about 3 weeks.

      Keep in mind as well that most women don’t know they are pregnant until after the first missed period so the time frame (human vs. mouse model) is accurate. As far as how much drinking would have to be done, well your guess is probably as good as mine, but I would suggest that this is equivalent to a woman who is moderately drinking before she notices she is pregnant.

      May 15, 2015 at 12:00 pm

  2. Breanna Brock

    The human central nervous system begins to form when the embryo is about 2 weeks old. The 3-6 weeks of the fetal development would be the best opportunity during the experiment to really see some changes. Most people do not realize how quickly after conception the fetus begins to form. The different portions of the brain are already evident at just 3 weeks, and this developing brain is very vulnerable. Toxic chemicals, such as alcohol, can effect the brain during early development. Drinking alcohol can be very dangerous to the fetus. It leads to thinning of the cerebral cortex that persists to adulthood. Alcohol also interferes with neuron proliferation and can kill neurons partly by apoptosis (a programmed mechanism of cell death). The mother may consume alcohol for several weeks before finding out she is expecting. All the while, homeobox genes are susceptible to mutations. This is how the infants can develop a brain disorder including mental retardation, as well as physical deformities. Were the scientists able to actually determine which specific genes were mutated? How exactly did the function of genes in the hippocampus of the mouse infant change?

    May 22, 2015 at 12:36 pm

    • I really appreciate you taking time to go over your train of thought, I agree that most people don’t realize how quickly a fetus forms (I mean 40 weeks isn’t a whole lot of time). So your questions, well those are both great questions and the short answers are yes and certain genes were upregulated and some were downregulated. The long answer (and the not so funny version, if you call what I just did funny) is:

      “… it was possible to detect significantly upregulated expression in two of the three tested genes. Olfr601 was upregulated in both the hippocampus and MOE of ethanol-exposed offspring. Vpreb2 was upregulated in the hippocampus and startlingly overexpressed in bone marrow. Vpreb2 is one of two mouse pre-B lymphocyte genes, Vpreb1 and Vpreb2, that are involved in B-cell development. A previous study has shown that the expression of Vpreb2 is significantly lower compared to Vpreb1 and it is not needed for the normal development of B cells …”

      That was directly from the paper itself, which is probably the most relevant part of the paper in regards to your questions. The researchers do go over other implications of the epigenetic changes that occurred when alcohol was given, but that would pretty much be the entire conclusions section of the paper. Thanks for asking and sorry it took so long to get you a reply, apparently I am busier than I thought.

      May 25, 2015 at 11:12 am

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