Amnio

Medical providers analyze this fluid during an procedure (typically between weeks 15 and 20) to check for:

Mostly water and electrolytes derived from maternal plasma. Medical providers analyze this fluid during an procedure

Becomes a mixture of fetal urine, lung secretions, and exfoliated fetal cells. Medical providers analyze this fluid during an procedure

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 Medical providers analyze this fluid during an procedure

According to WebMD , the fluid is dynamic and changes as the pregnancy progresses: