Fetal abortion refers to the death of an embryo or fetus that remains in the uterus, also known as “missed abortion”. Fetal abortion is a special form of spontaneous miscarriage. Unlike spontaneous miscarriage, most pregnant women have no obvious symptoms or discomfort after abortion, which is often detected by gynecological ultrasound. There are also some pregnant women who experience reduced or absent pregnancy reactions after fetal abortion, which are often ignored by pregnant women. Fetal abortion is more dangerous and difficult to deal with clinically. Most pregnant women have difficulty in clearing the uterus or clearing it again due to the long time of fetal arrest, which even leads to hemorrhage and uterine perforation. However, the death of fetus in the womb after 20 weeks of pregnancy is called fetal death; the death of fetus in the process of delivery is called stillbirth.
So, what causes fetal abortion?
The causes of fetal stoppage are very complex, including genetic factors, maternal factors, paternal factors, immune factors and mental factors.
1, genetic factors
(1) Chromosomal abnormalities in the embryo/fetus are the most common cause of fetal abortion.
Various types of chromosomal abnormalities can be detected in more than 60% of miscarried or arrested embryos, especially more than 80% of arrested/aborted embryos with abnormal gestational sac morphology have chromosomal abnormalities; even aborted/aborted embryos with normal gestational sac morphology have chromosomal abnormalities in about 25% of them. It was found that the earlier the time of miscarriage/arrest, the higher the rate of chromosomal abnormalities.
(2) Chromosomal translocations or inversions in one of the spouses (parental generation) lead to chromosomal abnormalities in the fetus and consequently cessation of development.
Chromosomal equilibrium translocations, rosettes and inversions are common in couples with a history of fetal abortion.
Parental chromosomal translocations have serious adverse genetic reproductive effects: if one spouse is a carrier of chromosomal translocations, there is a 1/18 chance that the offspring will be chromosomally normal, 1/18 will be a carrier of chromosomal translocations, and the remaining 16/18 will be unbalanced and abnormal, often resulting in birth defects or death.
Genetic counseling for parental chromosome rosettes: If one spouse is a carrier of chromosome rosettes, their offspring have 1/6 normal chromosomes, 1/6 carriers of chromosome rosettes, and the other 4/6 are unbalanced abnormalities, which manifest as developmental defects or death.
Parental chromosome inversion carriers: their offspring have 1/4 chromosomes normal, 1/4 chromosome inversion carriers, and 2/4 unbalanced abnormalities.
(3) Gene mutation and fetal abortion
Some genes play a role in promoting the occurrence of miscarriage in the process of miscarriage and are called miscarriage susceptibility genes; some genes prevent the occurrence of miscarriage and play a protective role in maintaining pregnancy. In addition, fetal pure gene mutations or compound heterozygous mutations can lead to abnormal fetal development or even death.
2.Maternal factors
(1) Maternal chronic diseases, reproductive tract infections and malnutrition can lead to miscarriage. Especially TORCH infection, Toxoplasma gondii infection, rubella virus infection, cytomegalovirus infection, herpes simplex virus infection, mycoplasma and chlamydia infection, etc. can lead to abnormal fetal development through vertical infection.
(2) Anatomical abnormalities of reproductive organs: such as uterine malformations, uterine adhesions, uterine fibroids, uterine polyps, uterine adenomyosis and cervical insufficiency, etc.
(3) Coagulation abnormalities: microthrombosis.
(4) Endocrine factors: abnormal luteal function, abnormal placental function, polycystic ovary syndrome, hyperprolactinemia, thyroid disease, and diabetes mellitus, etc.
3.Father factor
The male partner suffers from chronic systemic diseases, infection with pathogenic microorganisms, semen abnormalities, poor lifestyle habits, exposure to occupational factors, and the production of anti-sperm antibodies, etc.
4, immune factors
The immune factors causing fetal abortion include: ABO/RH maternal and child blood type incompatibility, maternal rejection
Sequestering antibody deficiency, antiphospholipid antibody syndrome and cytotoxic effects and increased activity of the complement system, etc.
5. Psychological factors
Pregnant women or women of childbearing age suffer from anxiety, depression, low self-esteem, guilt, autism, pessimism, insomnia and other adverse emotions, which lead to low body function and preferably cause immune dysfunction and finally lead to abnormal fetal development.