Early ultrasonographic detection of fetal growth retardation in an ovine model of placental insufficiency
Article Abstract:
An animal model of fetal growth retardation may enable better detection of fetal growth and the development of treatments for fetuses with defective placentas. Researchers induced fetal growth retardation by exposing four pregnant sheep to heat stress. Fetal growth retardation could be detected noninvasively by ultrasound. Previously, an invasive method was used to measure fetal growth in sheep. Growth retardation was evident by day 90 of the 147-day sheep pregnancy. Sheep fetuses followed a similar pattern of growth retardation as do human fetuses, with the growth rate of the brain preserved for as long as possible. It was unknown whether placental function and fetal growth would resume normally after heat stress was discontinued or if permanent damage resulted.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1995
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Doppler velocimetry of growth-restricted fetuses in an ovine model of placental insufficiency
Article Abstract:
Heat-stressed pregnant sheep provide a useful physiologic model of placental insufficiency and intrauterine growth restriction in humans. Researchers compared five pregnant ewes raised in a hot, humid facility with five raised in a conventional facility. The fetuses carried by heat-stressed ewes had higher systolic/diastolic blood pressure ratios and pulsatile indices in their umbilical arteries and aortas, as measured by Doppler velocimetry. As the fetuses grew, Doppler velocimetry index values fell with decreasing placental vascular resistance. Heat stress decreased placental blood flow.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1998
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Relationship of fetal growth to duration of heat stress in an ovine model of placental insufficiency
Article Abstract:
The adverse effects of stress on the fetus can be reduced by limiting the duration of the stress. Stress can lead to intrauterine growth restriction. Researchers exposed pregnant sheep to 55 days of heat stress or 80 days of heat stress and compared fetal outcomes to those of sheep not subjected to heat stress. Growth restriction at birth was evident in both groups exposed to heat compared to those not exposed to heat. The restriction was significantly greater in the sheep exposed to 80 days of heat stress.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1999
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