When a baby is delivered within 22-24th weeks of pregnancy, the baby cannot survive independently. This is called abortion. In developed countries, however, delivery before 20th week of pregnancy is considered as abortion. Among every 100 pregnancies, 10-20 pregnancies come to the conclusion through abortion. Among these, 75% occur during the first 12 weeks.
In 50% cases, abortion in first 3 months happens due to the chromosomal defects of the baby. In 10-15% cases, the deficiency of progesterone hormone in mother, deficiency or abundance of thyroid hormone and diabetes can be the reasons for abortion. The infections through bacteria, virus and parasites are liable for abortion in 5% cases.
When conception occurs, the embryo implanted inside the uterus. If the environment of this uterus becomes adverse for that fertilised embryo, it accounts for 10-15% cases of abortion. For example, if opening of uterus is loose, if there is a tumor in uterus, if there is any congenital defect in uterus, then that fertilised egg does not get any favorable environment to grow in that uterus. Then abortion takes place.
Among the couples, where husband's blood group is A and wife's blood group is O, there is also higher possibility of abortion. Smoking, drinking liquor, intra uterine contraceptive device, chemotherapy used for cancer treatment, arsenic, lead etc. can be responsible for abortion. Besides all these, in 40-60% cases, the actual reason behind abortion cannot be explained.
The women who give the history of abortion, they usually say their menstruation is stopped for a few days. In some cases they say, after the pregnancy test they found that they are pregnant, suddenly they experience bleeding through vagina and abdominal pain. Some give the history that they experience passage of some fleshy mass through vagina.
During the pregnancy, usually there is not supposed to be any kind of vaginal bleeding. In case of abortion the bleeding can be a few little drops. Its color can be purple red — in some cases, dark red or brown in color. Abdominal pain can be continuous, always there is pain in the lower abdomen. It can be frequent with some interval.
If the abortion is done by unskilled hand in unclean environment, or after abortion, if some part remains in the uterus, then there can be some infections. This infection, in 80% cases, is confined within the uterus. But in some cases, this infections spread to the adjacent organs, like fallopian tube and the ovary. It can be the cause behind the death of the mother.
If a pregnant woman with negative blood group experiences abortion, then within 72 hours of the abortion, Anti D Gamma Globulin injection should be instilled in her muscle.

The author is a Registrar, department of Gynecology and Obstetrics, Anwar Khan Modern Medical College.
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