Background: The interaction of hormonal factors are crucial for good foetal development. During the second trimester of gestation, most of the main physiological processes of foetal development occur. Therefore, the aim of this study was to determine the variations in the physiological levels of cortisol, estriol, estrone sulphate, and progesterone during the second trimester (weeks 12-26) in order to establish normal ranges that can serve as indicators of foetal well-being and good functioning of the foetal-placental unit.
Methods: Saliva samples from 106 pregnant women were collected weekly (from week 12 to week 26 of gestation), and hormonal measurements were assayed by an enzyme immunoassay. The technique used for hormone measurements was highly sensitive and served as a non-invasive method for sample collection.
Results: The results revealed a statistically significant (p<0.05) difference between cortisol, progesterone, and oestrogens throughout the second trimester, with a more substantial relationship between oestrogens and progesterone [P4-E3 (r=0.427); P4-E1SO4 (r=0.419)]. By analysing these hormone concentrations, statistically significant (p<0.05) elevations in progesterone, cortisol, and estriol levels were found at the 16th [(P4 (0.78±0.088), C(1.99±0.116), E3(2.513±0.114)]; 18th [(P4 (1.116±0.144), C(3.409±0.137), E3(3.043±0.123)] and 23rd week of gestation [(P4(1.36±0.153), C(1.936±0.11), E3(2.657±0.07)]. Estrone sulphate levels appeared to increase progressively throughout the second trimester [from 1.103±0.03 to 2.244±0.09].
Conclusion: The 18th week of gestation seems to constitute a very important week during foetal adrenal development, and the analysis of the main hormones involved in foetal development, provided more precise information regarding the proper functioning of the foetal unit and foetal development.
Keywords: Cortisol; Estriol; Estrone sulphate; Foetal development; Pregnancy; Progesterone.