The Science Behind: Miscarriages

Did you know that 1 in 5 pregnancies end in a miscarriage? They are more common than you think. However, they are not caused by unhealthy habits. More often than not, they are random. So, how exactly do miscarriages happen?



Most miscarriages occur because of a “chromosomal abnormality”. In order to understand

what that is, we need to know what chromosomes are.


Simply put, chromosomes are DNA molecules. Humans have 23 pairs of chromosomes, 46 chromosomes in total. You might have heard of the 23rd pair of chromosomes—they are known as sex chromosomes, as they decide the sex of the child. Females have two X chromosomes and males have one X and one Y chromosome.



A chromosomal abnormality is when the structure or number of chromosomes is different. The most common type of abnormality is called aneuploidy, meaning that there are either too many chromosomes or too few. Due to this, the fetus cannot develop normally, so it doesn’t survive.


However, aneuploidies do not always result in miscarriages. Sometimes a fetus with an abnormal number of chromosomes can still be born, but it will have a genetic disorder. Examples of genetic disorders are Turner syndrome (caused by a missing or partially missing sex chromosome in females) and Down syndrome (caused by an extra chromosome 21).


Chromosomal abnormalities are not the only reason miscarriages happen. Smoking, drinking, or any other drug abuse can cause a miscarriage. This is because everything the mother consumes during pregnancy affects the fetus as well. For example, if the mother smokes, nicotine goes into her blood, and the fetus loses oxygen. If it does not have enough oxygen, it dies in the womb.


Not-so-fun fact: Most miscarriages happen in the first trimester (the first 13 weeks of pregnancy). However, some do happen after the 20th week (5th month) of pregnancy. Those miscarriages are known as stillbirths.


Unhealthy lifestyles do cause miscarriages, but they are not the only cause. The most common reason miscarriages happen is that the fetus has an abnormal number of chromosomes. Since that is the case, miscarriages can happen to anyone.

If you want more information on miscarriages, check out the links below.


SOURCES:

https://www.livescience.com/51744-miscarriage-science-facts-myths-mysteries.html#:~:text=About%2060%20percent%20of%20the,chromosome%2021%20instead%20of%20two.

https://kidshealth.org/LAWW/en/parents/miscarriage.html#

https://www.ncbi.nlm.nih.gov/books/NBK115545/

https://www.genome.gov/about-genomics/fact-sheets/Chromosomes-Fact-Sheet#:~:text=is%20a%20chromosome%3F-,Chromosomes%20are%20thread-like%20structures%20located%20inside%20the%20nucleus%20of,type%20of%20living%20creature%20unique.


Cover page: https://www.pinclipart.com/picdir/big/201-2013870_early-miscarriage-awareness-day-clipart.png


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