Currently, prenatal examinations for women over the age of 35 mainly focus on early detection of fetal abnormalities. As a woman's eggs gradually develop from the fetal stage, the rate of egg aging and the occurrence of fetal abnormalities increase with age.
For older pregnant women, prenatal examinations primarily focus on early detection of fetal abnormalities. This is because a woman's eggs start developing from the fetal stage, and as age increases, the eggs gradually age, leading to a higher risk of fetal abnormalities. One common fetal abnormality caused by chromosomal abnormalities is Down syndrome, with maternal age being the main influencing factor.
A reputable source from the United States shows that the average risk of Down syndrome occurrence is approximately 1 in 800, while the risk for mothers aged 35 to 39 is 1 in 221, and for 40-year-old women, the risk is as high as 1 in 106.
Therefore, many doctors routinely recommend that women over the age of 35 undergo a diagnostic test called amniocentesis between 15 and 20 weeks of pregnancy to determine if the fetal chromosomes are normal. Another option is to first analyze the levels of certain substances in the mother's blood and calculate the probability of developing the disease based on age, gestational week, weight, etc. Based on the results, a decision can be made whether a confirmatory test is necessary. Currently, some major hospitals in China offer this type of examination.
