(마더세이프라운드) hyperthermia in pregnancy
TRANSCRIPT
HYPERTHERMIA IN PREGNANCY
PARK SUE YEON
.
HEAT• Heat, Heat stress, Hyperthermia
• Form of energy associated with kinetic motion of molecules
• Radiation, conduction or convection
• Total net heat load on the body
• Physiological effects of heat • Dukes-Dobos(1981), NIOSH Criteria Document (NIOSH, 1972)
• Exclude microwave radiation
• Source• Outdoors in hot climates, Indoors with poor ventilation
• Wearing heavy protective clothing, hot industrial processes
EFFECTS OF EXPOSURE
ACUTE EXPOSURE
Response① Rising in core body
temperature
② Increase in heart rate
③ Water and salt loss from excessive sweating
Heat illness1) Heat cramps : loss of salt
2) Heat exhasution
3) Heat stroke (41.1 °C ,106 ºF ↑)
Dehydration, electrolyte imbalance, skin rashes, heat edema, loss of mental and physical work capacity
CHRONIC EXPOSURE
Acclimatization① the heart rate ↓
② internal body temperature↓
③ Increased sweating
Variation of acclimatization • Dry heat versus wet heat
Loss of acclimatization
Heat cataracts
GENETIC EFFECTS
• DNA Damage/Repair• Radiated heat
• Form of electromagnetic radiation
• Interact with the genetic material
• Increase in preimplantation losses
• Chromosome abnormalities
• Sister chromatid exchange
• DNA polymerase was inactivated.
• Double-strand DNA breaks in cultured Chinese hamster ovary cells
REPRODUCTIVE EFFECTS IN HUMAN
• High fever in pregnancy and birth defectNormal body temperature : 37ºC (98.6ºF)
Core body temperature : 39 °C↑ (102.2 ºF)
Gestational days 14 to 28
Central nervous system • Microcephaly
• Hypotonia, Microopthalmia, Anencephaly and Occipital encephalocele
• Meningomyeloceles and Spina bifida(GA 25-28)
Spontaneous abortions
• Brief fever episode • No association in birth defects or decreased intelligence
• Acclimatization • Reduce the risk of CNS defects
REPRODUCTIVE EFFECTS IN HUMAN
• Definition of hyperthermia• Abnormally high body temperature: at least 38.3 ºC (101ºF) or ↑
• Causes • Fever related source
• Infection (viral or bacterial )
• Non Fever related source • Hot tubs or very hot baths • Saunas• Electronic blankets• Heavy exercise on hot and humid environments
• Teratogen Stage of embryonic development at the time of exposure Degree of temperature elevation, and its duration
• Threshold temperature for teratogenicity :38.9 ºC (102ºF)
• Development
1) Pre-implantation period (∼3 weeks)
Increased pre-implantation loss due to failure to implantation or embryonic death
2) Embryonic period (3∼8 weeks)
Period of major organogenesis
Especially, susceptible to the induction of developmental defect
CNS, skeletal, neuromuscular, and cardiac defect
3) Fetal periods (8 weeks~)
Results mainly in reduced growth & functional defects
• Mechanisms of defects
Apoptotic cell death
=> NTD, Microencephaly
Disturbance of neural crest cell and neuronal cell migration
=> Defects in heart and face
Hirschsprung disease, ectopic nests of neurons in the brain
Behavioral deficits and reduction in IQ
Damage to cell membrane
Damage to blood vessels & placenta
• Hypoplasia of limbs & toes(hypodactyly), exomphalos,
gastroschisis, possibly abortion and fetal growth restriction
• National Birth Defects Prevention Study Duong et al.2011
• Evaluation of risk for hot tub
• 20 healthy nonpregnant volunteers in hot tub heated to 39-41 ºC
• Measured vaginal temperatures while in hot tubs and saunas
• Leave to hot tub : 39 ºC ( 10 minutes) , 41.1 ºC(5 min)
• Maximum temperature and duration : no more than 15min at 39ºC
Harvey et al., 1981
• A study of 24 Australian women
• Hot tub set at 40°C until their temperatures reached 39°C with 54% of the subjects
not feeling uncomfortably hot
Ridge and Budd, 1990
HOT TUB
SAUNA BATHING
• Sauna bathing dose not seem to be associated with adverse
effects.
• 301 pregnant women
a. The high-fever group: 38.9 ºC (102°F) or above for at least 24 hr
b. The low-fever group: less than 102°F for any length of time, or a fever of 102°F
or above for less than 24 hr
• women in the high-fever group demonstrated a significantly increased rate of
major malformations
Chambers et al., 1997
RECOMMENDATION
• Environmetnal cuase
• Pontentially preventable
• Avoid and minimize risk
• 2005 Center for Disease Control and Prevention for reprouductive age
women
① Take 400 ug of supplemental folic acid
If Use hot tubs or spa
② Possibility to unkowingly be pregnant
③ Limit exposure in hot tub to < 15 min in 39 ºC and <10 min in 40ºC
④ Risk factor : not in good healthy, previously being in the hot tub or spa, fever,
exercise, or another source of hyperthermia, or begins to feel uncomfortable
• A woman who is or could be pregnant should be aware of the possible
variability in hot tub or spa temperature Chambers et al., 2006
• Study of children of New York
• No association between use electric blanket s or heated water beds and
incidence of cleft palate, cleft lip, or neural tube defects
• Exposed to 60-cycle
Dlugosz et al,1992
• The change thermoregulation during pregnancy
Change in the subjective perception of heat
Insufficient occupational data
ELECTRIC BLANKETS OR HEATED WATER BEDS
FERTILITY EFFECTS-FEMALE
• FERTILITY DECREASED FEMALE
• Physiological effects of heat on women
• Menstrual cycle
• Less adaptable to heat than men
• Women working in hot environments
• Increases uterine vascular resistance
• Decreases blood flow in high risk pregnancy
• No effect in normal pregnancy controls
FERTILITY EFFECTS-MALE
• FERTILITY DECREASED MALE
• Core body temperature : 38 ºC (100.4 F)
• Increase sperm abnormalities and infertility in the male
• Occupational study
• Increased risk of delayed conception , suggesting a weak effect
on male fertility.
• The temperatures were higher than those to which welders are
normally exposed