Causes & Contributing Risk Factors of Miscarriage

Often times the cause of miscarriage can not be easily determined. Since first trimester miscarriage is not considered a medical abnormality most doctors don’t recommend testing to determine the cause until at least 3 consecutive miscarriages have occurred.

Hormonal Factors:
Hormonal factors including polycystic ovarian syndrome, thyroid disorder and luteal phase defect have all been indicated as risk factors for miscarriage. Diagnosis and proper treatment and a plan for pregnancy should be considered with your physician before pregnancy to reduce miscarriage risk.

Chromosomal Abnormalities:
Chromosomal abnormalities are found in more then half of all miscarriages that occur before 13 weeks gestation. Most chromosomal abnormalities happen by chance and are not likely to recur. In the case of multiple loss due to chromosomal abnormalities, genetic testing of the parents can be done to screen for specific chromosomal abnormalities. Chromosomal abnormalities become more common as a woman ages. Women over 35 years old have a higher rate of miscarriage then younger women for this reason.

Certain infections/illnesses – both in the woman and fetus – are linked to an increase risk of miscarriage. A few of these infections include rubella, chlamydia, listeria monocytogenes, toxoplasmosa gondii, herpes simplex and parovirus B19.

Autoimmune Disorders:
Autoimmune disorders like lupus, celiac disease and diabetes can all increase your risk factor for miscarriage. Especially if you are not yet diagnosed and on a clear treatment path before pregnancy. Autoimmune disorders can cause the woman’s body to attack the growing fetus or will prevent the pregnancy from progressing causing miscarriage.

Structural Abnormalities:
Abnormal anatomy of the uterus can be a contributing risk factor for miscarriage – more likely in the early to late second trimester. Uterine septum, bicornuate uterus or fibroids can hinder healthy placenta attachment or hinder the growth of the fetus. Cervical abnormalities can also be a risk factor for miscarriage.

Clotting Disorders (Thrombophilias):
Clotting disorders – the most common being Factor V Leiden and prothrombin mutations and protein C and protein S deficiencies – can cause death of fetus due to a clot in the placenta, umbilical cord or within the mother. Miscarriage due to clotting disorders tend to occur after the 10th week of pregnancy or later in the second trimester (leading to possible stillbirth).

Lifestyle Factors:
Cigarette smoking – both by the mother and father – have been linked to an increased risk of miscarriage. Alcohol and drug use while pregnant are also strongly linked to miscarriage.


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Devan McGuinness

is the founder and executive director of the award-winning resource Unspoken Grief .

  1. Hello this is tasha, and thank you for speaking on this very emotional journey and I agree with it all,my experience was more so.sadden I was 31 got pregnant for the first.time miscarried at 4 half months it’s been two.years