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Fetal swallowing: response to graded maternal hypoxemia
1Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, Torrance 90509.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1991
Summary
Fetal swallowing and breathing decrease during maternal hypoxemia. Fetal swallowing is more sensitive to reduced oxygen levels than breathing, suggesting complex inhibitory mechanisms.
Area of Science:
- Perinatal Physiology
- Fetal Development
- Cardiovascular Regulation
Background:
- Maternal hypoxemia can impact fetal well-being.
- Understanding fetal responses to reduced oxygen is crucial for monitoring and intervention.
Purpose of the Study:
- To investigate fetal breathing and swallowing responses to graded maternal hypoxemia.
- To assess the correlation between fetal oxygen levels and these activities.
Main Methods:
- Utilized a computer-based system with electromyography (EMG) and esophageal fluid flow measurement.
- Monitored five chronically prepared ewes and their fetuses (130 days gestational age).
- Subjected fetuses to mild (FiO2=0.16) and moderate (FiO2=0.13) maternal hypoxemia.
Main Results:
- Maternal hypoxemia significantly reduced fetal arterial PO2.
- Moderate hypoxemia increased fetal arginine vasopressin and renin activity.
- Fetal breathing decreased from 53% to 25% and swallowing from 11.5% to 1.3% of the time.
- Fetal swallowing volume also significantly reduced.
Conclusions:
- Fetal swallowing is suppressed during mild and moderate hypoxemia.
- Swallowing activity showed a stronger correlation with fetal PO2 than breathing activity.
- Multiple sites and mechanisms may be involved in hypoxemic inhibition of fetal activities.