Maternal serum estrogen and progesterone concentrations preceding normal labor

Area of Science:

• Reproductive Endocrinology
• Maternal-Fetal Medicine

Background:

• Hormonal changes are critical throughout pregnancy and labor.
• Understanding the precise roles of estrogens and progesterone in labor initiation is ongoing.

Purpose of the Study:

• To simultaneously measure serum concentrations of estrone (E1), estradiol (E2), estriol (E3), and progesterone.
• To analyze hormonal patterns during late pregnancy, labor, and postpartum in normal women.

Main Methods:

• Serial blood sampling from 5 normal women during the last 3-10 weeks of pregnancy, labor, and postpartum.
• Measurement of serum E1, E2, E3, and progesterone levels.
• Analysis of diurnal variations and trends preceding labor using moving averages.

Main Results:

• Estrogen and progesterone exhibited minor diurnal variations during pregnancy.
• Hormone levels did not change significantly during labor but declined postpartum (except E1).
• Estriol (E3) showed a consistent rise 14-28 days before labor, while E1, E2, and progesterone lacked pre-labor surges or declines in maternal circulation.

Conclusions:

• Maternal serum estriol elevation precedes labor, potentially indicating fetal maturation or a role in labor's onset.
• Absence of significant changes in maternal peripheral E1, E2, and progesterone does not rule out their altered metabolism in fetal/uterine compartments as labor triggers.