Chronic fetal metabolic distress is demonstrated by which pattern of estriol levels?

• A. Decreased urinary estriol excretion and decreased maternal serum estriol
• B. Decreased estrogen in maternal plasma and increased estriol in amniotic fluid
• C. Increased estradiol in maternal plasma, with a corresponding increase of estriol in amniotic fluid
• D. Increased urinary estriol excretion and increased maternal serum estriol

Answer: (A)

Estriol levels in the mother reflect the function of the fetal–placental unit. In chronic fetal metabolic distress, placental insufficiency reduces estrogen production, so both maternal serum estriol and urinary estriol excretion fall. This concurrent decrease in circulating and excreted estriol best signals impaired placental function and sustained fetal stress. High estriol levels or increases in other estrogens typically indicate functioning placental estrogen synthesis, not distress, so they don’t align with the pattern described for chronic fetal compromise.