Patient's question:
At 40 days of pregnancy, I went to the hospital for a check-up. The doctor said everything was normal, but why did this happen when I reached two months? I'm very sad. This has happened to me twice. Is it related to my work environment? I'm involved in a business that deals with chemical toxic substances. Is this the reason, or is it due to chromosomal issues? Please help, experts.Doctor's answer:
The causes of miscarriage include:(1) Embryonic (or fetal) factors:
1. Abnormal embryonic development is the most common cause of early miscarriage, with chromosomal abnormalities accounting for approximately 50–60% of cases.
2. Placental abnormalities, such as incomplete trophoblast development, degeneration of placental villi, or low placental attachment, can disrupt fetal-placental circulation, leading to miscarriage.
(2) Maternal factors:
1. Acute infectious diseases may cause fetal death due to pathogens or toxins invading the placenta, or lead to miscarriage due to high fever or poisoning-induced contractions.
2. Severe anemia or heart failure may cause fetal hypoxia and death.
3. Endocrine disorders, such as luteal function insufficiency, can result in poor decidua development, impairing embryo growth.
4. Uterine malformation, uterine fibroids, or congenital anomalies may also hinder embryonic development.
5. Sometimes, cervical incompetence, where the internal os cannot withstand the pressure of the growing fetal sac, may cause late miscarriage.
6. Severe emotional stress, trauma, or sexual intercourse may also trigger miscarriage, though these are often contributing factors, with the primary cause typically being embryonic defects.
(3) External factors: Toxic substances that can cause miscarriage include cadmium, lead, organic mercury, DDT, and other radioactive materials. These toxic substances may directly affect fetal somatic cells or indirectly influence the fetus through the placenta, leading to miscarriage.
(4) Immunological factors: Maternal rejection of the fetus due to immune incompatibility between the mother and fetus may result in miscarriage. Known immunological factors include:
- Spousal histocompatibility antigens
- Fetal antigens
- Blood group antigens
- Maternal cellular immune regulatory imbalance
- Maternal (blocking antibodies) during pregnancy
- Lack of maternal cytotoxic antibodies against paternal lymphocytes
(5) Maternal-fetal blood type incompatibility: Blood type incompatibility between the mother and fetus often causes late miscarriage, such as in cases of ABO or Rh blood type mismatches.
It is recommended to:
- Test endocrine levels and anti-embryonic antibodies using electrochemical luminescence on days 3–5 of the menstrual cycle.
- Perform a vaginal examination on days 3–5 after menstruation, along with dynamic digital hysterosalpingography and 4D vaginal ultrasound.