Why spontaneous abortion?
summary
There are many reasons leading to spontaneous abortion, which can be divided into embryonic factors and maternal factors. The common causes of early abortion are chromosomal abnormality of embryo, endocrine abnormality of pregnant women, malformation of reproductive organs, infection of reproductive tract, local or systemic immune abnormality of reproductive tract, etc; The late abortion is mainly caused by cervical insufficiency, maternal fetal blood group incompatibility and other factors.
Why spontaneous abortion?
Chromosomal abnormality is the most common cause of spontaneous abortion. It is reported that 46% - 54% of spontaneous abortion is related to chromosomal abnormality. According to Warburton et al., the earlier abortion occurs, the higher the frequency of chromosomal abnormalities in embryos. Chromosomal abnormalities include quantitative abnormalities and structural abnormalities. Chromosomal trisomy is the first in the quantitative abnormalities, accounting for 52%. All kinds of trisomy have been found except for trisomy 1, among which chromosome 13, 16, 18, 21 and 22 are the most common, and trisomy 16 accounts for about 1 / 3; The second is monosomy 45, x, accounting for about 19%, which is the most common chromosomal abnormality next to trisomy. Triploid often coexists with placental vesicular degeneration. The fetus with incomplete vesicular mass can develop into triploid or trisomy of chromosome 16. The abortion is early, and a few survive. After continuous development, there are multiple malformations, and no live infant is found. The tetraploid live infant is rare, and the vast majority of very early abortion. The main structural abnormalities were chromosome translocation (3.8%) and chimera (1.5%). Chromosome inversion, deletion and overlap were also reported.
The abortion caused by immune factors, especially recurrent abortion and habitual abortion, can be divided into two types, namely autoimmune type and alloimmune type. Autoimmune type usually can detect various autoantibodies from patients, mainly antiphospholipid antibodies. Alloimmune patients were screened for common causes, so it is also called unexplained habitual abortion; These are mainly related to the poor physiological protective immune response during pregnancy, the lack of immunosuppressive factors or blocking factors, and eventually the embryo suffered from immune damage, leading to abortion.
Cervical incompetence: cervical incompetence is the main cause of abortion. Cervical incompetence is characterized by too short cervical canal or relaxation of cervical orifice. Due to the existence of anatomical defects, with the process of pregnancy, the uterus increases, uterine pressure increases, most patients in the middle and late pregnancy appear painless cervical tube regression, uterine dilatation, amniotic sac protrusion, rupture of membranes, and eventually abortion. Cervical dysfunction is mainly caused by local cervical trauma (delivery, midwifery, cesarean section, cervical conization, Manchester operation, etc.), and congenital cervical dysplasia is rare; In addition, exposure to diethylstilbestrol during embryonic period can also cause cervical dysplasia.
matters needing attention
When abortion occurs, do not rush to get pregnant again, should be more than half a year interval, so that the uterus can be fully recovered, the whole body of Qi and blood can be filled after pregnancy, otherwise the body has not yet fully recovered on pregnancy, easy to lead to abortion again, speed is not up to.
