According to WebMD , the fluid is dynamic and changes as the pregnancy progresses:
Contains antibodies, enzymes, and hormones (such as alpha-fetoprotein) used to screen for developmental issues. Clinical Purpose of Testing "Amnio Content" According to WebMD , the fluid is dynamic
Measuring alpha-fetoprotein levels to detect conditions like spina bifida. According to WebMD
Amniotic fluid—the "content" of an amnio—is primarily composed of (roughly 98%) during early pregnancy, but it also contains critical biological markers like fetal cells, proteins, and hormones that provide a window into the baby's health. Composition of Amniotic Fluid According to WebMD , the fluid is dynamic
Becomes a mixture of fetal urine, lung secretions, and exfoliated fetal cells.
In late pregnancy, it can be tested for surfactant levels to assess if the baby's lungs are developed enough for delivery.