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Theriogenology2012; 78(4); 759-767; doi: 10.1016/j.theriogenology.2012.03.023

Cortisol and progestin release, heart rate and heart rate variability in the pregnant and postpartum mare, fetus and newborn foal.

Abstract: The mechanisms leading to parturition in the horse in many aspects differ from those in other species. Pregnancy is maintained not by progesterone but by 5α-pregnanes and the progestin precursor pregnenolone originates from the fetus. As parturition approaches, the fetal adrenal switches from pregnenolone to cortisol synthesis but it is not known whether cortisol crosses the placenta. We hypothesized that in parallel to fetal cortisol release, cortisol in the maternal circulation increases before foaling and this increase can be determined in both saliva and plasma. In addition, maternal, fetal and neonatal heart rate and heart rate variability were measured. In 25 pregnant mares, saliva for cortisol analysis was collected 4 times daily from 15 days before to 5 days after foaling. In 13 mares, in addition, fetomaternal electrocardiogram (ECG) recordings were made and blood samples for progestin and cortisol analysis were collected once daily. Heart rate (HR) was recorded until 5 days after foaling. The heart rate variability (HRV) variables standard deviation of the beat-to-beat (RR) interval (SDRR) and root mean square of successive RR differences (RMSSD) were calculated. From Days 15 to 4 before parturition, progestin concentration increased (peak 267 ± 42 ng/mL) and decreased thereafter (P < 0.05, day of foaling 113 ± 18 ng/mL). A prepartum increase in maternal cortisol concentrations was evident in blood (P < 0.05) and saliva (P < 0.05) and paralleled the decrease in progestin concentrations. In mares, HR remained constant during the last days of pregnancy but decreased within one day after parturition (P < 0.05) while maternal HRV did not change. In the fetus and neonate, HR increased from before to after birth (P < 0.05) indicating increasing demands on the cardiovascular system with adaptation to extrauterine life.
Copyright © 2012 Elsevier Inc. All rights reserved.
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Publication Date: 2012-05-22 PubMed ID: 22626780DOI: 10.1016/j.theriogenology.2012.03.023Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research focused on the mechanisms leading to horse childbirth, specifically the role and changes in cortisol and progestin hormones, as well as alterations in heart rate and heart rate variability in the mother, fetus, and newborn horse. The researchers hypothesized an increase in maternal cortisol before childbirth, which can be identified in both saliva and plasma. The study analyzed heart rate and fluctuations in heart rate and used these findings to discern a change in cardiovascular demands resulting from the transition to life outside of the womb.

Overview of Study Methodology and Design

  • The study population involved 25 pregnant mares. Out of this group, 13 mares were selected to also undergo fetomaternal electrocardiogram (ECG) recordings.
  • Saliva samples were collected from the mares four times a day, from 15 days prior to 5 days after foaling.
  • In the subset of 13 mares, blood samples were also taken daily for progestin and cortisol analysis.
  • ECG recordings were used to document heart rate (HR) until five days post-foaling. From this data, researchers analyzed heart rate variability (HRV), calculating the standard deviation of the beat-to-beat interval (SDRR) and the root mean square of successive RR differences (RMSSD).

Key Findings and Observations

  • From 15 to 4 days prior to labor, the concentration of progestin significantly rose, peaking at 267 ± 42 ng/mL, and dropped thereafter. The progestin level on the day of foaling was lower at 113 ± 18 ng/mL.
  • A notable rise in maternal cortisol concentrations was recorded in the blood and saliva before childbirth, coinciding with the decline in progestin concentration.
  • The mares’ heart rates did not change during the final days of pregnancy but decreased within the first day after labor. However, maternal HRV did not exhibit any changes.
  • In the fetus and neonate, the heart rate increased from before to after birth. This suggested escalating cardiovascular demand as the newborn adjusts to life outside the womb.

Conclusion

The research indicates that cortisol levels in pregnant mares increase prior to childbirth, as reflected in both blood and saliva. These cortisol changes are associated with changes in progestin levels. Moreover, changes in heart rate in mares and their offsprings reflect the different cardiovascular demands before, during, and after birth.

Cite This Article

APA
Nagel C, Erber R, Bergmaier C, Wulf M, Aurich J, Möstl E, Aurich C. (2012). Cortisol and progestin release, heart rate and heart rate variability in the pregnant and postpartum mare, fetus and newborn foal. Theriogenology, 78(4), 759-767. https://doi.org/10.1016/j.theriogenology.2012.03.023

Publication

Theriogenology
ISSN: 1879-3231
NlmUniqueID: 0421510
Country: United States
Language: English
Volume: 78
Issue: 4
Pages: 759-767

Researcher Affiliations

Nagel, C
  • Graf Lehndorff Institute for Equine Science Neustadt (Dosse), University of Veterinary Sciences, Vienna, Austria. christina.nagel@vetmeduni.ac.at
Erber, R
    Bergmaier, C
      Wulf, M
        Aurich, J
          Möstl, E
            Aurich, C

              MeSH Terms

              • Animals
              • Animals, Newborn / physiology
              • Female
              • Fetus / physiology
              • Heart Rate / physiology
              • Heart Rate, Fetal / physiology
              • Horses / blood
              • Horses / embryology
              • Horses / physiology
              • Hydrocortisone / analysis
              • Hydrocortisone / metabolism
              • Parturition / blood
              • Parturition / metabolism
              • Parturition / physiology
              • Postpartum Period / blood
              • Postpartum Period / physiology
              • Pregnancy
              • Pregnancy, Animal / blood
              • Pregnancy, Animal / metabolism
              • Pregnancy, Animal / physiology
              • Progestins / analysis
              • Progestins / blood
              • Saliva / chemistry
              • Saliva / metabolism
              • Time Factors

              Citations

              This article has been cited 15 times.
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