• deprived infants;
  • physiological development;
  • sleeping body temperature


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°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°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.