Cause of Miscarriage in First Trimester


Minister's of Penmai
May 21, 2011
Miscarriage during the first trimester is most common in women when compared with the other two trimesters. It is also known as spontaneous abortion. About 80% of the miscarriages happen within the 20 weeks of gestation. Sometimes miscarriage takes place even before the women knew that she is pregnant. Loss ofpregnancy can be natural or accidental.

There are many possible causes of miscarriage in first trimester. These could be genetic, uterine, hormonal and chromosomal abnormalities, reproductive tract infections, and tissue rejection.

  • Chromosomal abnormalities are responsible for around 50% of the first trimester pregnancy loss. Amongst the miscarriages due to chromosomal abnormalities, majority occur due to autosomal trisomy (22.3%) followed by monosomy (8.6%), triploidy (7.7%) and tetraploidy (2.6%).

  • Collagen vascular diseases can be the other cause of first trimester miscarriage. It is a disease in which the body’s immune system attacks its own organs. In this the woman's body starts making antibodies against its own tissues. Examples of collagen vascular diseases are systemic lupus erythematosus and antiphospholipid antibody syndrome.

  • Diseases such as diabetes, kidney and heart diseases too cause first trimester pregnancy loss.
  • Hormonal factors such as Cushing syndrome, thyroid diseases and Polycystic hormone syndrome are also associated with the risk of first trimester miscarriage. Inadequate production of progesterone due to malfunctioning of the corpus luteum may also lead to first trimester miscarriage. This defect is termed as luteal phase defect.​
  • Abnormal structure of the uterus can also lead to pregnancy loss. A septate uterus, a unicornuate uterus and a bicornuate uterus are the deformities which can cause miscarriage. Fibriods, interuterine adhesions and an incompetent womb can also cause pregnancy loss.

Apart from all these factors there are some avoidable reasons also, which when overlooked can cause first trimester miscarriage. They include:

  • Lifestyle factors such as smoking, drinking alcohol, or using illegal drugs.

  • Use of certain medications, such as the acne drug Accutane.

  • Severe malnutrition can also cause miscarriage.

  • Exposure to high level of radiation, pesticides, formaldehyde, lead and certain industrial solvents can also cause early pregnancy loss.
First trimester miscarriage cannot always be avoided, as there may be pre-determining factors with each pregnancy. However, a healthy lifestyle and regular prenatal care can decrease the risk of first trimester miscarriage and can increase the chance of a full-term delivery. A balanced diet followed by light exercises like swimming, walking and yoga will keep you fit and energized. First trimester miscarriage is not an uncommon event and there are all the chances for a successful pregnancy post its occurrence.


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