Emily Sears and Professor Joann Abegglen, College of Nursing
Extrauterine growth, or growth outside the womb following birth, is a serious challenge and concern in premature neonates. Preterm infants have low birth weights simply because they have not reached full growth and development at the time of birth. In addition to prematurity itself, preterm infants can be classified by low or very-low birth weights (VLBW), meaning they are even smaller than other neonates of the same gestational age. If extrauterine retarded growth rate occurs during the early periods of growth and development, preterm infants are at increased risk for poor health outcomes, including failure to thrive, stunted growth, delays in cognition, and possibly death. According to a comprehensive study on reducing growth retardation outside the womb, “[e]xtrauterine growth restriction (EGR) is a major clinical problem for prematurely born neonates, especially critically ill preterm neonates, and malnutrition in the neonatal intensive-care unit remains common.” Promoting adequate growth in preterm infants in NICUs through better nutritional protocol and other interventions is a concern world-wide, even in the United States.
Although the phenomenon of EGR in premature infants is a worldwide health problem, it bears particular significance in Tucamàn, Argentina, one of the poorest provinces in the country. In 2003, Argentina reported neonatal mortality rates of 11 (out of 1000 live births) and an infant mortality rate of 17. Argentina’s neonatal and infant mortality rates are somewhere in the middle when ranked with other Central and South American countries, though the same categories of mortality rates in the United States are 5 and 7, respectively. However, recent changes in Argentina, and in Tucamàn in particular, have led to more positive outcomes for neonates, premature or otherwise. In 2000, the country of Argentina was applauded for reducing infant mortality rates by more than 10%, a goal set forth by the World Summit for Children in 1990, by introducing programs that promoted breast-feeding and other nutritional practices to improve growth and development.
Methodology: Data collected by Dr. Catherine Coverston in Tucamàn, Argentina and Dr. Robert D. Christensen in IHC facilities in Utah were compared with the most recent comprehensive study regarding premature and VLBW infant growth rates as published by Ehrenkranz et al. in Pediatrics in 1999. See Table 1 below for a comparison of data sets from each of these studies.
A comparison of Dr. Christensen’s study within IHC facilities in Utah and Dr. Coverston’s study in Tucamàn, Argentina to that of Ehrenkranz et al. shows each group of infants studied experienced varying levels of weight gain, with Argentine babies exhibiting the lowest rates of weight gain. Certainly, growth rates in one of the poorest provinces of Argentina will differ greatly from those exhibited by several large corporate hospitals in the Intermountain West in the US; however, both these studies and the data collected by Erhenkranz et al. independently found that most preterm and VLBW babies did not meet the growth targets as expected by extrauterine growth curves. In Tucamàn only 6.3% of preterm infants were in the 10th percentile of weight for their age, with only 3.4 % meeting the 50th percentile and 1.9% of infants meeting the 90th percentile. In comparison, the Ehrenkranz et al. study also found that most hospitalized VLBW neonates were not able to reach the expected growth rates as determined by the conventional growth rate trajectories, even though their weight gain rates are much higher than Argentine growth rates; they used their own collected data points to construct new growth curves which they felt more accurately depicted the normal growth rates in premature and VLBW neonates. While the weight gain rates collected by Dr. Christensen are similar to the growth rates experienced by the Ehrenkranz study, Dr. Christensen and his colleagues interpreted their results much differently. Rather than universally interpreting their growth rates as inadequate, the IHC study used their collected data points to form new growth rate curves and compared them to the traditional growth rate trajectories. While the authors of this study realized that their new growth trajectories may not exemplify the “ideal weight changes . . . we speculate that . . . [the findings are] not a local phenomenon seen in our health system.” Instead of finding their growth rates to be insufficient, both Dr. Christensen and Ehrenkranz et al. suggest that currently accepted growth curves are perhaps inaccurate projections of actual growth and thus should be reevaluated.
References
- Clark, R.H., Wagner, C.L., Merritt, R.J., Bloom, B.T., Neu, J., Young, T.E., et al. (2003). Nutrition in the neonatal intensive care unit: How do we reduce the incidence of extrauterine growth restriction [Electronic version]. Journal of Perinatology, 23, 337-344.
- World Health Organization [WHO]. (2003). Neonatal and Infant Mortality Rates by Country. Region of the Americas. Retrieved October 16, 2006 from www.who.int/child-adolescent-health/OVERVIEW/CHILD _HEALTH/ Mortality_Rates_03.pdf.
- Pan-American Health Organization [PAHO]. (2000). Annual Report of the Director. Retrieved October 17, 2006 from http://www.paho.org/English/D/ar2000-3.pdf.