Why is Miscarriage More Common in the First Trimester?

A miscarriage is when a pregnancy is lost or ends unintentionally before the 20th week of gestation. Early pregnancy loss, or a miscarriage before 13 weeks of gestation (during the first trimester), is the most common type of miscarriage. But Why Do Miscarriages During the First Trimester Occur?

Miscarriages in the first trimester can occur for wide variety of causes, but it’s important to keep in mind that often, the reasons for early pregnancy loss are not well understood. Some of the most common causes of miscarriage in the first trimester are:

Genetic abnormalities – When an embryo receives the incorrect chromosomes from the egg and sperm, this commonly leads to miscarriage.

Illness or infection in the mother– If the mother is suffering from another condition, it could lead to pregnancy loss. This can be due to infection (STIs, food poisoning, malaria, and others), chronic illness (like diabetes or other autoimmune disorders), or other diseases.

Hormonal imbalances– Hormones levels (specifically progesterone) are key to maintaining a pregnancy in its initial stages.

Uterine problems – Uterine fibroids and other anatomical abnormalities of the uterus can interfere in the proper implantation and growth of a fetus.

Cervical insufficiency– A condition in which the cervix is not strong enough to hold a pregnancy and the fetus is lost.

Genetic abnormalities are one of the main causes of miscarriages. According to the American College of Obstetricians and Gynecologists, approximately one half of all cases of early pregnancy loss are due to an embryo receiving an incorrect number of chromosomes. Although the exact reason for this is not known, scientists believe it may have something to do with which chromosomes are switched or missing, as this can affect the growth and organ development of the fetus.

Non-invasive Prenatal Testing for Genetic Abnormalities

If you are 35 or older, or if you have had several miscarriages in the past, your doctor may suggest that you undergo non-invasive prenatal testing to determine if your fetus has a chromosomal abnormality. This test is performed using only a blood sample and poses no potential harm to the developing fetus. However, if the results show that further diagnostic testing is necessary, your doctor may recommend more invasive tests that may carry higher risks.

Preventive Measures for Other Risk Factors

Your doctor may also recommend that you stay away from certain substances and activities while in your first trimester. While studies have not shown that these particular substances directly influence early pregnancy loss, they have been identified as potential risk factors for the pregnancy:

Drugs, Alcohol, Smoking, Caffeine, Talk to Your Doctor

If you are pregnant and would like to know more about risk factors for miscarriages, preventing miscarriages, or prenatal testing, make an appointment with your doctor today.

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