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Correlation of nocturnal increase in plasma oxytocin with a decrease in plasma estradiol/progesterone ratio in late
A R Fuchs1, O Behrens, H C Liu
1Department of Obstetrics and Gynecology, Cornell University Medical College, New York, NY 10021.
American Journal of Obstetrics and Gynecology
|December 1, 1992
Summary
Plasma oxytocin concentrations exhibit a daily rhythm, peaking at night. This circadian pattern in oxytocin may be linked to uterine activity and hormonal changes during late pregnancy.
Area of Science:
- Reproductive endocrinology
- Maternal-fetal medicine
Background:
- Hormonal fluctuations are common during pregnancy.
- Oxytocin plays a crucial role in uterine contractions and labor.
Purpose of the Study:
- To investigate the presence of a daily rhythm in plasma oxytocin levels.
- To explore the relationship between oxytocin rhythm and other key hormones.
Main Methods:
- Radioimmunoassay was used to measure oxytocin, estradiol, progesterone, and cortisol in plasma samples from pregnant women.
- Blood samples were collected at three time points: 8 AM, 4 PM, and midnight.
- Statistical analysis included Friedman's test and multiple range testing.
Main Results:
- A significant daily rhythm was observed for plasma oxytocin, cortisol, and progesterone.
- Plasma oxytocin levels showed a distinct nocturnal peak.
- Oxytocin levels were negatively correlated with the estradiol/progesterone ratio.
Conclusions:
- The daily rhythm of plasma oxytocin parallels that of uterine activity, suggesting a potential causal link.
- Hormonal rhythms, including oxytocin, may be influenced by the circulating estradiol and progesterone ratio.