Daily and hourly temporal association between delta-4-androstenedione-induced preterm myometrial contractions and maternal plasma estradiol and oxytocin concentrations in the 0.8 gestation rhesus monkey

Article Abstract:

Mild uterine contractions occurring before labor may become stronger labor contractions because of an increase in estrogen levels. Researchers used eight rhesus monkeys in late pregnancy to study the relationship between estrogen and oxytocin levels and the strength of uterine contractions. Estrogen and oxytocin levels were measured before and after labor induction, and before and after nighttime, which is when uterine contractions in the pregnant monkey normally increase. Estrogen levels increased after labor induction, and these increases preceded increases in oxytocin levels by 24 to 48 hours. Increases in oxytocin levels correlated with stronger uterine contractions. Increases in oxytocin levels precipitated by elevations of estrogen may cause preterm labor as well as term labor.

Causes of, Labor (Obstetrics), Premature labor, Estrogen, Estrogens

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Alteration of fetal oxygenation and responses to acute hypoxemia by increased myometrial contracture frequency produced by pulse administration of oxytocin to the pregnant ewe from 96 to 131 days' gestation

Article Abstract:

Fetuses seem to adapt to uterine contractions that alter the level of oxygen in amniotic fluid. This was the conclusion of a study of pregnant sheep who were given oxytocin to stimulate uterine contraction or saline solution, which would have no effect on uterine contraction. Fetal lambs of ewes who received oxytocin had higher oxygen levels than the other lambs. In these lambs, the fetal blood oxygen dissociation curve shifted to the left, indicating that the lambs had adjusted to uterine contraction.

Research, Fetal anoxia

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Level of postoperative analgesia is a critical factor in regulation of myometrial contractility after laparotomy in the pregnant baboon: implications for human fetal surgery

Article Abstract:

Increasing the dose of opioid analgesics may reduce the risk of uterine contractions after surgery. In a study of baboons who had surgery, a double dose of the analgesic buprenorphine suppressed the rise in estrogen levels that occurred after a normal dose. The number of uterine contractions was greater in the monkeys who received a normal dose. This indicates that elevated estrogen levels can cause uterine contractions and that a double dose of buprenorphine can counteract the effect of estrogen.

Fetus, Surgery, Dosage and administration, Fetal surgery, Analgesics

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