Causes of miscarriage in first trimester could be genetic, uterine or hormonal and chromosomal abnormalities, reproductive tract infections, and tissue rejection. Learn what are the possible causes of miscarriage in the first trimester of pregnan
A miscarriage that happens in the first trimester or within the first 12 weeks of pregnancy is also called spontaneous abortion. About 80% of the miscarriages happen within 12 weeks of gestation.
First trimester miscarriage is not uncommon, though a miscarriage does not necessarily mean that conceiving in the future is impossible. Some of the possible causes of miscarriage in the first trimester of pregnancy include the following.
Chromosomal or genetic abnormalities are the most common causes identified in the early loss of pregnancy. 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%). Either of the parents can have such abnormalities or the foetus can develop them within the first 12 weeks of gestation.
In their book, When Pregnancy Fails: Coping with Miscarriage, Stillbirth and Infant Death, Susan Borg and Judith Lasker say, “The timings of miscarriage gives the first clue as to possible cause. Seventy-five percent occur within the first twelve weeks, and about one half of these “early” miscarriages are due to an abnormality in the embryo or in the process of its implantation in the uterus. The foetus may be deformed because of genetic problems inherited from the parents, but more often a chance mutation has occurred during fertilization or the early growth of the embryo.” Unfortunately, chromosomal abnormality in the foetus can be treated.
Collagen vascular diseases
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 disease, the woman's body starts making antibodies against its own tissues. The Collagen Vascular diseases are autoimmune diseases that Medica- a Journal of Clinical Health associates with pregnancy loss and foetal abnormalities. “During early pregnancy, subclinical autoimmune processes seem capable of causing both pregnancy loss as well as congenital fetal abnormalities such as congenital heart block. Several disorders that are historically associated with pregnancy loss – such as collagen vascular diseases (most notably systemic lupus erythematosus), chronic active hepatitis, inflammatory bowel disease, diabetes mellitus and thyroid disease – are autoimmune disorders.”, states Medica. The Vascular diseases that result in maximum first trimester pregnancy loss are systemic Lupus Erythematosus and Antiphospholipid Antibody Syndrome. A blood test can be done to detect these diseases and start their timely treatment before they cause repeated miscarriage.
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 (Luteal Phase Defect) due to malfunctioning of the corpus luteum may also lead to first trimester miscarriage. The hormone progesterone is essential for the development of pregnancy. It aids in proper implantation of the embryo and its deficiency can hinder the embryo from implanting itself on the uterine lining. Women’s Health Associates, a team of certified gynaecologists and other practicing health professionals, says, “It has been suggested that inadequate function of the corpus luteum in the ovary (which produces progesterone necessary for maintenance of the very early stages of pregnancy) may lead to miscarriage”.
Luteal Phase Defect can be diagnosed by a blood test and an endometrial biopsy. To prevent miscarriage, your doctor on the basis of your tests can prescribe you progesterone supplements for luteal support. If you are already pregnant, treatment of Luteal Defect will be with vaginal suppositories of natural progesterone or intramuscular injections of progesterone for the first 12 weeks.
Abnormal structure of the uterus can also lead to pregnancy loss. A septate uterus, a unicornuate uterus and a bicornuate uterus are the deformities that can cause miscarriage in the first trimester. Fibriods, interuterine adhesions and an incompetent womb can also cause pregnancy loss. Susan Borg and Judith Lasker have further said in their book titled In Search of Parenthood that, “There may also be abnormalities in the structure of the uterus itself, such as double uterus. Sometimes, the cervix is overtly weak (“incompetent’) and dilates too early. This may be a result of previous surgery on the cervix.”
The immunity system has a major role to play in the maintenance of pregnancy throughout the trimesters and protecting foetus against infections, bacteria and viruses. If the mother’s immune system is weak or incompetent to safeguard the foetus against “invaders” which may come with father’s genes, there are strong chances of miscarriage in the early stages of conception. In couples who experience miscarriage, the maternal immune system restrains from accepting the father’s foreign material that the foetus carries, resulting in loss of pregnancy.
- Environmental Factors: Women, who have continuous exposure to toxic chemicals and fumes, are at a risk of early miscarriage. These toxic substances inhibit a foetus’s growth, causing inappropriate development and subsequent pregnancy loss. Exposure to high level of radiation, pesticides, formaldehyde, lead and certain industrial solvents can also cause early pregnancy loss.
- Smoking and Alcohol abuse: Women who smoke or drink are more likely to have miscarriage than those who don’t. According to the American Society for Reproductive Medicine, “Smoking is strongly associated with an increased risk of spontaneous miscarriage and possibly ectopic pregnancy as well. Pregnant smokers are more likely to have low birth weight babies and premature birth”.
- Malnutrition: Malnutrition in pregnant women is directly linked to loss of pregnancy in its early stages. The deficiency of essential nutrients in the mother implies lack of supply of the same to the foetus, affecting its normal growth and development and eventually, resulting in miscarriage.
Physical and emotional trauma is a potential cause of miscarriage. Physical trauma that can lead to spontaneous termination of pregnancy can be prolonged working hours, strenuous work routine, physical harassment and torture. Emotional trauma includes fear, grief, depressed state of mind and stress, however, health professionals believe that more research is required to know the possible association between emotional trauma and miscarriage.
First trimester miscarriage cannot always be avoided as there may be pre-determining factors with each pregnancy. A healthy lifestyle and regular prenatal care, however, can decrease the risk of first trimester miscarriage and can increase the chance of a full-term delivery.
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