THERMOREGULATORY CHANGES IN PREGNANCY

1. THERMOREGULATORY
CHANGES IN
PREGNANCY
LAILA

2. DEFINITION
Thermoregulation is the balance between heat production and heat
loss involved in maintaining thermal equilibrium. Heat is produced by
the body as a by-product of metabolic processes and muscular activity;
thus a major function of the thermoregulatory system is dissipation of
this heat. The thermoregulatory system must also respond
appropriately to alterations in environmental temperature to preserve
thermal equilibrium. Maintenance of thermal stability is particularly
critical in the newborn in that exposure to cold environments and
lowered body temperatures are closely correlated with survival,
especially in very low–birth weight (VLBW) infants.

3. Maternal physiologic adaptations
 The increase in maternal temperature during pregnancy may cause
transient discomfort and alter the woman’s heat tolerance. The major
concerns related to thermoregulation during pregnancy are the effects
of maternal hyperthermia and fever on the fetus.
 Hormonal and metabolic alterations during pregnancy result in changes
in maternal temperature.

4. Antepartum period
 The amount of heat generated increases 30% to 35% during
pregnancy because of the thermogenic effects of
progesterone, alterations in maternal metabolism and basal
metabolic rate and maternal dissipation of heat generated by
the fetus.

5.  The maternal temperature usually increases by 0.5° C (0.3° F). Both core and
skin temperature increase during pregnancy, with a slight decrease reported in
late pregnancy. The core temperature peaks by midpregnancy. The decrease in
core temperature in late pregnancy may be related to decreases in
progesterone and physical activity (which generates heat) during this time. The
rise in skin temperature is particularly evident in the hands and feet, probably
due to arteriovenous shunting in these areas. In general, heat accumulation
may be slower and heat dissipation faster in later pregnancy than before
pregnancy or in early pregnancy.

6.  Body temperature increases with exercise due to heat generated by
increased metabolic energy production. Some of this heat is
dissipated by increased skin blood flow; the remainder is stored ,
increasing the core temperature. Changes in temperature with
exercise during pregnancy are more compared to non pregnant
woman, suggesting that the enhanced thermoregulatory capacity of
the pregnant woman may help protect her against hyperthermia.

7. Intrapartum period
An increase in body temperature, averaging 1° C (1.7° F), may occur during
labor as a result of physical activity with uterine contractions and the release
of substances from the fetal-placental unit that may stimulate the maternal
hypothalamic thermoregulatory center.
Infection
epidural analgesia

8. Cont…….
 The laboring woman is also at risk for hypothermia during the intrapartum
period due to vasodilation (limiting usual vasoconstrictive responses to
cold); administration of anesthetics, narcotics, and other pharmacologic
agents; blood loss, rapid cool fluid replacement, or other events that
increase maternal heat loss (e.g., cold towels).
 Hypothermia can result in shivering, hypotension, and hemodynamic and
cardiorespiratory instability.

9. Postpartum period
 Maternal temperature elevation during the postpartum period
may indicate ;
 infection e.g bacterial endometritis, mastitis or UTI
 or dehydration

10. MANAGEMENT
 Management of hyperthermia in pregnancy depends on the cause
 e.g
 Mild fever -paracetamol
 Infection -Antibiotics
 Dehydration -rehydrate