Abnormal Development - Maternal Hyperthermia

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Introduction

High core body temperature, hyperthermia, has been shown in animal models to be a potent teratogen. Hyperthermia in humans (greater than 39.5°C/103°F) during the first trimester increases the risk of a miscarriage and neural defects. Hyperthermia can be due to many different factors including: environment, hot tubs, spas, sauna, exercise, infection fever (viral, bacterial), physiological abnormalities of thermoregulation.

Hyperthermia and hypothermia.jpg

Guinea pigs have been successfully used as a sensitive model system for the effects of maternal hyperthermia (high body temperature/fever) upon development. This is an example of a maternal environmental effect on embryonic development and neurological effects has also been demonstrated in other rodent model systems.

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Some Recent Findings

  • Effects of maternal hyperthermia on myogenesis-related factors in developing upper limb.[1] "Our data suggest that maternal hyperthermia delays limb myogenesis in part by disregulating the expression of key myogenesis-related factors."
  • Multiple congenital abnormality syndrome in the offspring of pregnant women affected with high fever-related disorders[2] "Our previous study showed an association between high fever-related maternal diseases during the second and/or third gestational months and a higher risk of multiple congenital abnormalities (MCA) in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities."

Diurnal Temperature Changes

In humans there are a number of small changes that occur each day and associated with the menstral cycle, neither of which are significant enough to cause hyperthermia.

Firstly there natural diurnal small changes in core body temperature that occur each day.

Diurnal body temperature.jpg

Secondly, in women of reproductive age there occurs also a small approximately 0.5°C increase in body temperature associated with ovulation during the menstral cycle. This temperature rise is often used in reproductive cycle monitoring to aid or avoid pregnancy.

Neural Tube Defects

Neural tube and other developmental anomalies in the guinea pig following maternal hyperthermia during early neural tube development.[3] "Guinea pigs were exposed to hyperthermia for 1 hr once or twice on day 11, 12, 13, or 14 (E11-E14) of pregnancy. The mean rectal temperatures were elevated by 3.4°C -4.0°C. This treatment resulted in a marked elevation of rates of resorption and developmental defects in embryos examined at day E23. The defects observed were those affecting the neural tube (NTD) (exencephaly, encephaloceles, and microphthalmia), kyphosis/scoliosis, branchial arch defects, and pericardial edema. Embryos with NTD and kyphosis/scoliosis have not been found among newborn guinea pigs to date following maternal heat exposure on days E12-E14. It appears that embryos with these defects are filtered out by resorption or abortion by days E30-E35."

Marsh Edwards

Edwards: discoverer of maternal hyperthermia as a human teratogen.[4] "In a series of animal studies performed over a career spanning 40 years at the University of Sydney, Professor Marshall J. Edwards investigated the hypothesis that maternal hyperthermia during gestation can be teratogenic to the developing fetus. He is one of few investigators to have discovered a known human teratogen primarily through animal studies. His doctoral thesis was entitled "A Study of Some Factors Affecting Fertility of Animals with Particular Reference to the Effects of Hyperthermia on Gestation and Prenatal Development of the Guinea-Pig". He went on to prove that hyperthermia-induced malformations in animals involve many organs and structures, particularly the central nervous system. ... In a series of carefully planned and executed experiments, he demonstrated that the type of defect is related to the timing of the hyperthermic insult, and analyzed the underlying mechanisms.

References

  1. <pubmed>19180648</pubmed>
  2. <pubmed>18983582</pubmed>
  3. <pubmed>1354895</pubmed>
  4. <pubmed>16265640</pubmed>

Reviews

Articles

<pubmed>16998815</pubmed> <pubmed>16847614</pubmed>

Search Pubmed

June 2010 "Maternal Hyperthermia"

Search Pubmed: Maternal Hyperthermia

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Cite this page: Hill, M.A. (2024, March 28) Embryology Abnormal Development - Maternal Hyperthermia. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Abnormal_Development_-_Maternal_Hyperthermia

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