Overnight deep body temperature and urinary cortisol excretion in infants from economically deprived areas.

OBJECTIVES

To assess the pattern of postnatal physiological maturation in economically deprived infants by measuring the age-related changes in deep body temperature during night-time sleep.

SETTING

Inner city Leicester, UK.

PARTICIPANTS

Forty-eight infants aged 6-21 weeks from economically deprived areas and 87 control infants from more affluent areas.

OUTCOME MEASURES

Average deep body temperature between 2 and 4 h after bedtime, overnight and early morning urinary cortisol excretion.

RESULTS

Both groups showed a decline in overnight deep body temperature with age that averaged 0.030 degrees C per week (SE = 0.003). Over the age range studied, the average age-adjusted overnight temperature in the infants from deprived homes was 0.090 degrees C (SE = 0.028) higher than that for the affluent group (P = 0.001). Deprived infants had on average 51% higher overnight urinary cortisol and 80% higher morning cortisol. The differences remained when the effects of room temperature, clothing, smoking, birthweight and gestational age were taken into account.

CONCLUSION

These indicators of postnatal physiological maturation suggest that infants from economically deprived homes mature less quickly. This might increase their vulnerability to illness.