Genetic (chromosomal) abnormalities
represent the single most frequent cause for miscarriages. Chromosomes are microscopic components of every cell in the body that carry all of the genetic material that determine hair color, eye color and our overall appearance and makeup of our physique. Abnormal number of chromosome or some error in the chromosome can happen by chance during cell division in the egg. When this takes place, miscarriages can happen. Miscarriages may be the nature's way to prevent abnormal babies being born.
Other causes of spontaneous abortions may be factors related to the mother's health. Miscarriage from these causes usually occurs later in pregnancy. They include-
Chronic diseases such as diabetes or high blood pressure
Problems with the immune system
Abnormalities of the uterus or cervix such as cervical incompetence, in which the cervix begins to dilate too early in pregnancy. This nearly always occurs in the second trimester (after 3 months).
Drugs, smoking or alcohol abuse
Exposure to environmental toxins