Related Experiment Video
Updated: Apr 17, 2026
Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings
Published on: October 25, 2015
Fetal surgery and maternal cortisol response to stress. The myelomeningocele sheep model
Gloria Pelizzo1, Carlo Valerio Bellieni2, Clara Dell'Oste3
1a Department of Maternal and Children's Health, Pediatric Surgery Unit , Fondazione IRCCS Policlinico San Matteo and University of Pavia , Pavia , Italy .
Background:
Prenatal surgery represents a multifactorial stressor event for mother and fetus. The stress response to fetal surgery was evaluated by measuring maternal plasma and amniotic fluid (AF) cortisol levels in the myelomeningocele (MMC) sheep model.
Subjects And Methods:
Pregnant ewes (n = 8) underwent general anesthesia for MMC-induction (step 1: 75 d gestation), surgical defect repair (step 2: 110 d gestation), and delivery (step 3: 140 d gestation). Maternal blood samples were taken before surgery (surgical stage T1), after laparotomy and uterine exposure (surgical stage T2), at the end of the procedure (surgical stage T3). Fetal stress was evaluated by measuring cortisol levels in AF after hysterotomy at steps 1-3.
Results:
Maternal cortisol concentrations at T2 and T3 increased compared with T1 (p = 0.019 and p = 0.046). AF cortisol response increased from 1 to 3 surgical steps and during pregnancy. The AF cortisol level was lower than maternal serum levels (induction p < 0.001; repair p < 0.001; caesarean section p < 0.001).
Conclusions:
Hysterotomy was the most stressful event in the ewes. Fetuses seemed to be partially protected from the high maternal cortisol levels. The fetal stress response to prenatal surgery increased with gestational age. Pain perception development, fetal maturation, and "pain memory" are probably associated with this increase.
