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Early physiological development of infants with intrauterine growth retardation
J A Jackson1, M P Wailoo, J R Thompson
1Department of Child Health, University of Leicester and University of Warwick, UK.
Insights
Intrauterine growth retarded (IUGR) infants show slower physiological adaptation, with delayed maturation of body temperature, heart rate, and cortisol excretion compared to healthy newborns. This prolonged immature state may increase risks for future cardiovascular issues.
Area of Science:
- Neonatal physiology
- Developmental pediatrics
- Endocrinology
Background:
- Intrauterine growth retardation (IUGR) affects fetal development, potentially impacting postnatal physiological adaptation.
- Understanding the maturation patterns in IUGR infants is crucial for identifying long-term health risks.
Purpose of the Study:
- To investigate the early postnatal physiological adaptation and maturation in infants with intrauterine growth retardation (IUGR).
- To compare the development of diurnal rhythms in sleeping body temperature, heart rate, and urinary cortisol excretion between IUGR infants and controls.
Main Methods:
- A study involving 65 IUGR infants and 127 matched controls, with measurements taken in their homes.
- Monitoring of deep body temperature, heart rate, and urinary cortisol concentrations during sleep.
- Analysis of age-related changes and differences between IUGR and control groups.
Main Results:
- IUGR infants exhibited a slower decline in minimum overnight body temperature and established adult-like diurnal rhythms later than controls.
- Higher average minimum overnight heart rates were observed in IUGR infants compared to controls.
- IUGR infants showed significantly higher overnight urinary cortisol/creatinine ratios, indicating prolonged physiological immaturity.
Conclusions:
- Postnatal physiological adaptation and maturation are delayed in IUGR infants, leading to an extended period of physiological immaturity.
- Elevated heart rates and cortisol excretion in IUGR infants may serve as early indicators for potential hypertension and cardiovascular disease later in life.
Objectives:
To assess the patterns of early postnatal physiological adaptation and maturation in intrauterine growth retarded (IUGR) infants by measuring changes in sleeping deep body temperature, heart rate, and concentrations of urinary cortisol.
Setting:
At home.
Patients:
Sixty five IUGR babies and 127 controls matched for sex, social class, and levels of parental smoking.
Results:
Night time sleeping deep body temperature, heart rate, and cortisol excretion fell with age, eventually establishing an adult type diurnal rhythm of physiological function. Minimum overnight temperature showed a linear decline with age (p < 0.001), but the IUGR infants and the controls had significant differences in intercept (p = 0.007) and slope (p = 0.02). The estimated rate of decline per week was 0.020 degrees C for IUGR infants and 0.031 degrees C for controls. Maximum temperature did not show similar changes. IUGR infants had a mean (SE) age adjusted minimum overnight heart rate that was 4.2 (1.5) beats/min (p = 0.005) higher than controls. Overnight cortisol/creatinine ratios declined with age at a rate of 4.1% per week (log ratio -0.421 (0.0165), p = 0.01), but the ratio for IUGR infants was on average 42% higher (log ratio 0.35 (0.11), p = 0.002) than for controls of the same age. Morning cortisol concentrations did not show a similar pattern.
Conclusions:
Postnatal physiological adaptation and maturation of IUGR infants is slower than normal and therefore they remain in a physiologically immature state for longer. The higher heart rates and greater cortisol excretion in such infants may be precursors to hypertension and cardiovascular disease seen in adults.
