Is there any harm to pregnant women after rectal cancer radiation?

The embryo is most sensitive to radiation within 6 days after fertilization. It is generally believed that it is dangerous to be exposed to X-rays during the first 15 weeks of pregnancy. The breakage of embryonic cell chromosomes and gene mutation can cause miscarriage, stillbirth, neonatal death, congenital malformations such as microcephaly, microeyes, hydrocephalus, as well as developmental delay and intellectual disability.

There are reports that long-term follow-up of infants born to pregnant women who underwent abdominal X-ray examinations showed an increased incidence of leukemia compared with normal children.
Since B-ultrasound has been widely used, most obstetric examinations that were previously performed using X-rays can now be replaced by B-ultrasound, so the use of X-rays has become less and less.
The radiation and cosmic rays in the natural environment expose you to at least 90 to 200 millirads per year. However, in places where there is a lot of radiation in nature, fetal digestive system malformations are more common.
The extent of radiation damage to the fetus depends on the following factors:
1. Gestational age: At 10 weeks of pregnancy, the development of the fetus' organs is initially complete, but not perfect. Radiation exposure before 15 weeks of pregnancy can cause fetal malformation, and after 15 weeks of pregnancy, it can also cause developmental delays in the fetus's systemic and cranial nerve systems.
2. Parts and doses of radiation: Fetal radiation doses of more than 10 rads (radiation measurement unit) are prone to teratogenicity, 5 to 10 rads are likely to cause teratogenicity, and less than 5 rads are not. The closer the irradiated part is to the fetus, the greater the radiation dose received.