PEDIATRICOBESITY ORIGINALRESEARCH
Body composition at birth in preterm infants between 30 and 36 weeks gestation S. E. Ramel1, H. L. Gray2, B. A. Davern1 and E. W. Demerath2 1
Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA; 2Department of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, USA Received 5 September 2013; revised 4 November 2013; accepted 19 November 2013
Summary Background: The American Academy of Pediatrics calls for aggressive management of preterm infants to achieve body composition approximating that of the healthy infant in utero. Air displacement plethysmography (ADP) has been validated for assessment of body composition in preterm infants and could be used to monitor their nutritional status during hospitalization. Comparative datasets on body composition at birth among healthy, live-born preterm infants are lacking.
Objective: The aim of this study is to provide the first descriptive fat mass (FM) and fat-free mass (FFM) data from healthy newborn preterm infants at birth as a proxy for healthy in utero body composition. Methods: Body mass and volume were obtained using ADP within 72 h of birth in 98 singleton, appropriate-for-gestational-age preterm infants. FM and FFM were calculated using the Fomon equation. Results: Measurement with ADP was feasible and well tolerated by infants as young as 30 weeks gestation and 1 kg, appropriate for gestational age (AGA; defined as between the 10th– 90th percentile on a standard reference curve (16)) and able to tolerate room air for >5 min without significant desaturation or bradycardia. Exclusion criteria included congenital conditions known to affect fetal growth and time from birth to consent >72 h.
These criteria were developed so that the study sample represented healthy, (albeit preterm) newly born infants and would be useful during a time period when nutritional alterations are feasible and tolerated. These criteria were influenced by the limitations of ADP, which only allow measurement of infants >1 kg and off of respiratory support. We restricted inclusion to those able to be measured within 72 h of birth to minimize the influence of post-natal illness and treatment. Approval was obtained from the Institutional Review Board at the University of Minnesota and written consent was obtained from the parent(s) of each participant.
Procedures Once consent was obtained, medical record information was gathered on infant sex, GA (and its method of determination; either ultrasound prior to 12 weeks or last menstrual period) and number of hours elapsed between birth and testing. Parental weights, heights and infant race/ethnicity were determined by parent self-report. Maternal diabetes status (gestational diabetes mellitus, type 1 and type 2 diabetes mellitus) was obtained from the delivery record. Weight, supine length and head circumference were measured at one time point between 24 and 72 h of age. The infant’s mass was measured on an electronic scale accurate to the nearest 0.1 g. Supine length was measured on an infant length board (Perspective Enterprises Inc., Portage, MI, USA) to the nearest 0.1 cm. Head circumference was measured using a flexible cloth measuring tape to the nearest 0.1 cm. Body composition was assessed using the PEA POD. A detailed description of the PEA POD’s physical design, operating principles, validation and measurement procedures is provided elsewhere (20–24). A 20-s infant mass measurement using the integrated electronic scale of the PEA POD is followed by a 2-min body volume measurement in the test chamber. Body density is then computed from body mass and volume. The PEA POD uses the principles of whole body densitometry to derive FFM, FM and BF% using measured body density, constant FM density (0.9007 g mL−1) (26,27), and age- and sex-specific FFM density coefficients using the Fomon equation (28). The equation also accounts for the estimated effect of total body water changes on changes in fat-free density during the first few days of life (28–30). Newborns were measured without clothing, and adjustments were made for the weight and volume of any articles unable to be detached from the infant (nasogastric tubes, umbilical clips, pulse oximetry monitor, etc.). All infants wore a tight fitting
© 2014 The Authors Pediatric Obesity © 2014 International Association for the Study of Obesity. Pediatric Obesity 10, 45–51
cap to minimize volume measurement artifact from excessive hair. Infant heart rate and oxygen saturation were monitored continuously via wireless techniques throughout the study visit (NONIN Medical Inc., Plymouth, MN, USA), and the protocol was halted if heart rate was 200 or oxygen saturation was
Body composition at birth in preterm infants between 30 and 36 weeks gestation S. E. Ramel1, H. L. Gray2, B. A. Davern1 and E. W. Demerath2 1
Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA; 2Department of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, USA Received 5 September 2013; revised 4 November 2013; accepted 19 November 2013
Summary Background: The American Academy of Pediatrics calls for aggressive management of preterm infants to achieve body composition approximating that of the healthy infant in utero. Air displacement plethysmography (ADP) has been validated for assessment of body composition in preterm infants and could be used to monitor their nutritional status during hospitalization. Comparative datasets on body composition at birth among healthy, live-born preterm infants are lacking.
Objective: The aim of this study is to provide the first descriptive fat mass (FM) and fat-free mass (FFM) data from healthy newborn preterm infants at birth as a proxy for healthy in utero body composition. Methods: Body mass and volume were obtained using ADP within 72 h of birth in 98 singleton, appropriate-for-gestational-age preterm infants. FM and FFM were calculated using the Fomon equation. Results: Measurement with ADP was feasible and well tolerated by infants as young as 30 weeks gestation and 1 kg, appropriate for gestational age (AGA; defined as between the 10th– 90th percentile on a standard reference curve (16)) and able to tolerate room air for >5 min without significant desaturation or bradycardia. Exclusion criteria included congenital conditions known to affect fetal growth and time from birth to consent >72 h.
These criteria were developed so that the study sample represented healthy, (albeit preterm) newly born infants and would be useful during a time period when nutritional alterations are feasible and tolerated. These criteria were influenced by the limitations of ADP, which only allow measurement of infants >1 kg and off of respiratory support. We restricted inclusion to those able to be measured within 72 h of birth to minimize the influence of post-natal illness and treatment. Approval was obtained from the Institutional Review Board at the University of Minnesota and written consent was obtained from the parent(s) of each participant.
Procedures Once consent was obtained, medical record information was gathered on infant sex, GA (and its method of determination; either ultrasound prior to 12 weeks or last menstrual period) and number of hours elapsed between birth and testing. Parental weights, heights and infant race/ethnicity were determined by parent self-report. Maternal diabetes status (gestational diabetes mellitus, type 1 and type 2 diabetes mellitus) was obtained from the delivery record. Weight, supine length and head circumference were measured at one time point between 24 and 72 h of age. The infant’s mass was measured on an electronic scale accurate to the nearest 0.1 g. Supine length was measured on an infant length board (Perspective Enterprises Inc., Portage, MI, USA) to the nearest 0.1 cm. Head circumference was measured using a flexible cloth measuring tape to the nearest 0.1 cm. Body composition was assessed using the PEA POD. A detailed description of the PEA POD’s physical design, operating principles, validation and measurement procedures is provided elsewhere (20–24). A 20-s infant mass measurement using the integrated electronic scale of the PEA POD is followed by a 2-min body volume measurement in the test chamber. Body density is then computed from body mass and volume. The PEA POD uses the principles of whole body densitometry to derive FFM, FM and BF% using measured body density, constant FM density (0.9007 g mL−1) (26,27), and age- and sex-specific FFM density coefficients using the Fomon equation (28). The equation also accounts for the estimated effect of total body water changes on changes in fat-free density during the first few days of life (28–30). Newborns were measured without clothing, and adjustments were made for the weight and volume of any articles unable to be detached from the infant (nasogastric tubes, umbilical clips, pulse oximetry monitor, etc.). All infants wore a tight fitting
© 2014 The Authors Pediatric Obesity © 2014 International Association for the Study of Obesity. Pediatric Obesity 10, 45–51
cap to minimize volume measurement artifact from excessive hair. Infant heart rate and oxygen saturation were monitored continuously via wireless techniques throughout the study visit (NONIN Medical Inc., Plymouth, MN, USA), and the protocol was halted if heart rate was 200 or oxygen saturation was
