A large proportion of fertilized eggs or embryos do not make it past the early days of pregnancy. A number of times the mother may not even be aware that she has conceived if the miscarriage happens before or even shortly after implantation. This is known as chemical pregnancy. A chemical pregnancy can only be confirmed through a biochemical test, such as an hCG blood or urine test. It is too early to be detected by an ultrasound test.
Sometimes a home pregnancy test may show a faint positive result but a later test may show a negative result. When this happens the woman may get her period at the expected time. The period may be heavier than usual and clots and small amounts of tissue may also pass out with the blood. There may also be slight or even severe cramps. This is a sign that she may have suffered from an early miscarriage. If the bleeding continues for longer than usual a doctor needs to be consulted to check for an incomplete miscarriage.
Early miscarriages usually happen due to the unviability of the embryos, where there may be a chromosomal defect in the embryo. Usually the human gene contains forty-six chromosomes, out of which twenty-three comes from the father and twenty-three from the mother. Sometime during the complex process of chromosome exchange during conception an incorrect number of chromosomes may cross over leading to the creation of a defective embryo. As this embryo grows at some point the mother’s body realizes this and, recognizing the embryo as unviable, expels it from the body. This type of miscarriage is the result of an abnormal result of conception and is not caused due to the body’s inability to meet the needs of pregnancy. This is mostly a one off event and unlikely to be repeated.
Once the pregnancy can be detected by ultrasound it is then called a clinical pregnancy. A miscarriage that happens after twelve weeks is no longer an early miscarriage. After twelve weeks, miscarriages may happen for various reasons. Women who are at a higher risk of having a miscarriage are those who suffer from uncontrolled chronic conditions such as diabetes, those who have auto immune diseases such as PCOS (poly-cystic ovary syndrome). This risk of having a miscarriage also depends on age and the higher the age of the mother, the higher is the risk of having a miscarriage. There could be a hormonal deficiency or physiological abnormalities of the uterus or cervix.
In some cases, the pregnancy may continue after showing some signs of miscarriage. This is known as a threatened abortion and the doctor usually prescribes bed rest for the patient in case there are initial signals that a miscarriage may occur, but the miscarriage does not actually happen. The doctor may also prescribe medications to stabilize the pregnancy.