HYPERTHERMIA IN PREG-NANCY

PARK SUE YEON

Division of Maternal-Fetal Medicine Fellowship.Department of Obstetrics and Gynecology.

Cheil General Hospital and Women’s healthcare center.

Kwandong University College of Medicine.

HEAT• Heat

– Form of energy associated with kinetic motion of molecules– Radiation, conduction or convection – HEAT, HEAT STRESS, or HYPERTHERMIA

• Total net heat load on the body• Occupational exposure recommendations

• Physiological effects of heat – Dukes-Dobos(1981), NIOSH Criteria Document (NIOSH, 1972) – Exclude microwave radiation

• SOURCES– Outdoors in hot climates, Indoors with poor ventilation– Wearing heavy protective clothing, hot industrial processes

EFFECTS OF ACUTE EXPO-SURE

• Response Rising in core body temperature Increase in heart rate Water and salt loss from excessive sweating

• Heat illness1) Heat cramps : loss of salt2) Heat exhasution3) Heat stroke

Exceeds 41.1 degrees C (106 degrees F) failure of the thermoregulatory processing body temperature Immediate removal to a cool environment, cooling measures, and

medical supportive care4) Dehydration, electrolyte imbalance, skin rashes, heat edema,

loss of mental and physical work capacity

EFFECTS OF CHRONIC EXPO-SURE

• Acclimatization – Decrease in the heart rate – Decrease in internal body temperature– Increased sweating

• Variation of acclimatization – Dry heat versus wet heat

• Loss of acclimatization

• Prickly heat : – form of dermatitis – Blockage of the sweat glands

• Heat cataracts

GENETIC EFFECTS

• DNA DAMAGE/REPAIR

– Radiated heat : form of electromagnetic radiation

1) Increase in preimplantation losses2) Chromosome abnormalities3) Sister chromatid exchange 4) DNA polymerase was inactivated. 5) Double-strand DNA breaks in cultured Chinese hamster

ovary cells

REPRODUCTIVE EFFECTS IN HUMAN

• High fever in pregnancy and birth defect Core body temperature : 39 degrees C (102.2 degrees F) Gestational days 14 to 28 Central nervous system :

• Microcephaly • hypotonia, microopthalmia, anencephaly , and occipital en-

cephalocele, 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 higher• Normal body temperature : 37ºC (98.6ºF)

• Causes • Fever due to infection (viral or bacterial )• Hot tubs or very hot baths • Saunas• Electronic blankets• Heavy exercise on hot and humid environments

REPRODUCTIVE EFFECTS IN HUMAN

• Teratogen Stage of embryonic development at the time of expo-

sure• Pre-implantation period • After implantation

Degree of temperature elevation, and its duration

• Threshold temperature for teratogenicity :38.9 ºC (102ºF)

REPRODUCTIVE EFFECTS IN HUMAN

• Development

1) Pre-implantation period (∼3 weeks)Increased pre-implantation loss due to failure to im-plantation or embryonic death

2) Embryonic period period of major organogenesis (3∼8 weeks)Especially, susceptible to the induction of developmental de-fectCNS, 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, gastroschi-

sis, possibly abortion and fetal growth restriction

REPRODUCTIVE EFFECTS IN HUMAN

•Neural plate and neural tube stages

•Neural tube, eye, face, heart, and vertebral forma-tion

•Embryo is susceptible to damage of heat•Brain : anencephaly, exencephaly, spinabifida and en-cephalocele•Eyes : anophthalmia, microphthalmia, defects of the iris•Face : small upper or lower jaws, cleft of the face•Heart

•After neural tube closes to form the brain and spinal cord Vertebrae and ribs become susceptible to damage

REPRODUCTIVE EFFECTS IN HUMAN

REPRODUCTIVE EFFECTS IN HUMAN

• Hot tub– Measured vaginal temperatures of 20 non-pregnant

women while in hot tubs and saunas– Use of hot tubs for limited time : 10-15 minutes

(Harvey et al., 1981)

– Hot tub set at 40°C until their temperatures reached 39°C with 54% of the subjects not feeling uncomfort-ably hot

– A study of 24 Australian women

(Ridge and Budd, 1990)

SAUNA BATHING• Sauna bathing dose not seem to be associated

with adverse effects.– 301 pregnant women a. The high-fever group: 102°F(38.9ºC) 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)

• limit exposure in the hot tub – 15 minutes in 29 degrees centigrade – 10 minutes in 40 degrees water. – Shortened if other sources of temperature elevation are present

(e.g. fever, exercise)

(Chambers et al., 2006)

REPRODUCTIVE EFFECTS IN HUMAN

• Electric blankets or heated water beds• 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 neu-ral 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

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 degrees C (100.4 degrees 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

Thank you for your atten-tion!!