A monthly cycle in the adrenocortical function during third trimester pregnancy

Area of Science:

• Endocrinology
• Reproductive Biology
• Maternal-Fetal Medicine

Background:

• Previous research indicated monthly cycles in aldosterone and progesterone during pregnancy.
• The existence of parallel monthly cycles in other key hormones remained unexplored.

Purpose of the Study:

• To investigate monthly cyclical changes in serum cortisol, human chorionic gonadotropin (hCG), and estradiol during the third trimester of pregnancy.
• To corroborate previous findings on monthly aldosterone and progesterone cycles using a consistent methodology.

Main Methods:

• A semiparametric statistical model was applied to analyze serum hormone concentrations.
• Blood samples were collected from eleven healthy pregnant women three times weekly during the third trimester.

Main Results:

• A highly significant monthly cycle was detected in serum cortisol levels.
• Monthly cycles in aldosterone and progesterone were confirmed.
• The cycle amplitude for hCG was barely significant, and non-significant for estradiol.

Conclusions:

• The findings suggest the presence of a persistent monthly adrenocortical cycle during pregnancy.
• This cycle may parallel the non-pregnant ovarian cycle, with linked changes in aldosterone-progesterone and cortisol-estrogen.
• The precise physiological mechanisms controlling this monthly endocrine cycle in pregnancy are currently unknown.