What are the reasons for the fetal arrest in the fourth month of pregnancy?

After pregnancy, the healthy development and growth of the fetus is what the couple is most concerned about. The child's condition can generally be detected through a pre-pregnancy physical examination. During pregnancy, many pregnant women find that their babies have miscarriage at four months. They are very anxious because they have never encountered such a situation before. So, what are the reasons for fetal arrest at four months of pregnancy? Let’s take a closer look below.

Endocrine disorders

Embryo implantation and continued development depend on the coordination of a complex endocrine system. Any abnormality in any link can lead to miscarriage. During the early development of the embryo, three important hormone levels are required: estrogen, progesterone, and human chorionic gonadotropin. As for the mother, if her own endogenous hormones are insufficient, it cannot meet the needs of the embryo and may cause embryo arrest and miscarriage. The most common of these is luteal dysfunction, which can cause delayed endometrial development and a short luteal phase, thereby affecting the implantation of the fertilized egg or early pregnancy miscarriage. People with luteal insufficiency are often accompanied by other glandular dysfunctions, such as hyperthyroidism or hypothyroidism, diabetes, relative androgenism and hyperprolactinemia. These factors are not conducive to embryonic development and are closely related to miscarriage.

Immune factors

The embryo or fetus in the uterus is actually an allogeneic transplant because the fetus is a combination of the genetic material of the parents and cannot be exactly the same as the mother. Immune incompatibility between mother and fetus causes the mother to reject the fetus. Common autoimmune diseases include systemic lupus erythematosus, scleroderma, mixed connective tissue disease, dermatomyositis, etc. The second is the issue of reproductive immunity. If we carry certain antibodies ourselves, it may affect the development of the embryo. In fact, the antibody testing in each hospital is different, and the doctors' opinions are also different. From our research perspective, we believe that there are four influencing factors. The first is anti-sperm antibodies. If present, they may resist the combination of sperm and egg; the second is anti-endometrial antibodies. If anti-endometrial antibodies exist, they may affect the development of the embryo and resist the development of the embryo; the third is anti-ovarian antibodies. If present, they will affect the quality of the egg; the fourth is anti-chorionic gonadotropin antibodies. This hormone is actually an important hormone that is secreted seven days after the sperm and egg combine. However, if this antibody exists in the body, it will resist the secretion of the hormone, which may cause embryonic arrest.

Uterine abnormalities

Both the internal environment of the uterus and the overall environment of the uterus may have an impact on the embryo. The internal environment is the endometrium. If it is too thin or too thick, it will affect implantation. About 10% to 15% of miscarriages are caused by uterine defects. Common ones include (1) congenital abnormalities of the Müllerian duct, including unicornuate uterus, didelphic uterus, septate uterus, and bicornuate uterus, which result in a narrow uterine cavity and restricted blood supply. Abnormal development of the uterine arteries can lead to asynchrony of decidualization and abnormal implantation. (2) Intrauterine adhesions, which are mainly caused by intrauterine trauma, infection or residual placental tissue, leading to intrauterine adhesions and fibrosis. Hinders normal decidualization and placental implantation. (3) Uterine fibroids and endometriosis cause reduced blood supply, leading to ischemia and venous dilatation, asynchronous decidualization, abnormal implantation, and hormonal changes caused by fibroids, which can also cause pregnancy failure. (4) Congenital or traumatic cervical relaxation and abnormal cervical development caused by intrauterine treatment with diethylstilbestrol often lead to mid-term miscarriage.

Chromosome problems

If the chromosomes are abnormal, it may cause the embryo to not develop and lead to early miscarriage. Chromosome abnormalities include quantitative and structural abnormalities. Quantitative abnormalities can be divided into aneuploidy and polyploidy. The most common abnormal karyotype is triploidy, and trisomy 16 accounts for 1/3 and is often lethal. 25-67% of pregnancies with trisomy 21, 4-50% of pregnancies with trisomy 13, and 6-33% of pregnancies with trisomy 18 will result in miscarriage. Others include haploid (4SX), and tetraploidy results in embryonic failure due to abnormal cleavage. Structural abnormalities include deletions, balanced translocations, inversions, overlaps, etc. Balanced translocation is the most common chromosomal abnormality. Current research on chromosomes believes that chromosomes pair, exchange and separate to form gametes, and gametes combine to form zygotes. If one of the zygotes is abnormal, it will lead to abnormal development, which may cause miscarriage, stillbirth, or deformed babies. Therefore, prenatal diagnosis is needed to prevent the birth of children with chromosomal diseases. Western medicine currently has no effective treatment for miscarriage, fetal growth retardation, etc. caused by chromosomal abnormalities, and can only provide prenatal genetic counseling and diagnosis. For chromosomal abnormalities, theoretically, there is a chance of giving birth to a normal karyotype or a carrier baby. Prenatal diagnosis can be performed on these couples to ensure the birth of a normal baby. Of course, current research also shows that the chromosomes of both spouses are normal, but chromosomal abnormalities occur during gamete formation and embryo development. If a woman is older than 35 years old, her eggs are aging and chromosome nondisjunction is likely to occur, leading to chromosomal abnormalities; semen abnormalities, such as macrocephalic sperm, are mostly diploid, and after fertilization, polyploid embryos are formed, leading to miscarriage. Adverse environmental influences such as toxic chemicals, radiation, high temperature, etc. can also cause embryonic chromosomal abnormalities. Therefore, the key to preventing fetal growth retardation due to chromosomal abnormalities is to regulate the bodies of both husband and wife so that the functions of various internal organs are coordinated and normal, yin and yang are balanced, pregnancy is achieved through selection, and the couple stays away from adverse environments.

The above is an introduction to the reasons for fetal arrest in the fourth month of pregnancy. I hope it will be helpful to everyone’s understanding. There are many reasons that lead to fetal arrest in the fourth month of pregnancy. The key is to find the cause based on your own situation. Given that this situation is relatively complicated, it is best to go to a regular gynecological hospital for diagnosis and treatment. Issues related to the child's health must be resolved in a timely manner.