Incidence of neonatal of definition hypoglycemia." A matter William R. Sexson, M.D., LTC, USAF, MC Wright Patterson AFB, Ohio A NEW DEFINITION OF NEONATAL HYPOGLYCEMIA has recently been proposed. Specifically, it has been suggested that "glucose [values in the newborn infant] should be maintained at >40 mg per 100 ml. ''~ This lower limit is clearly higher than that recommended by Corn- blath et al? and by Gutberlet and Cornblath.3 Additional- ly, there has been a recent emphasis on early postnatal monitoring in infants considered to be at increased risk for hypoglycemia? These risk factors 4'5 are widely recognized and are listed in the Table. The combination of early monitoring plus the use of a higher glucose level to define hypoglycemia could lead to an increase in the number of hypoglycemie infants detected and therefore the number given treatment. To date, no studies have been done to indicate the incidence of hypoglycemia using this revised and higher definition. The purpose of this study was to evaluate the incidence of neonatal hypoglycemia in a population of infants in a level 1 nursery, with hypoglycemia defined as a glucose value <40 mg/dl. METHODS All infants born during the 4 months between January and April 1980 were included prospectively. Our hospital sees generally low-risk obstetric and neonatal patients, with only rare referrals either into or out of the system. Ready access to prenatal care is available at no cost to pregnant women. From the Department of Pediatrics, USAF Medical Center, Wright-Patterson AFB. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or representing the view of the Department of the Air Force or the Department of Defense. Reprint requests: William R. Sexson, M.D., LTC, USAF, MC, Department of Pediatrics, Wright-Patterson USAF Medical Cen- ter, Wright-Patterson AFB, OH 45433. The study infants were all inborn and were brought within the first 15 minutes after birth to a transitional (recovery room) nursery, where they were monitored until successful transition to the extrauterine environment. The babies were placed under radiant warmers, and a brief physical examination and gestational age assessment were done by a trained nurse. Weight and gestational age were plotted using the Newborn Maturity Rating and Classifi- cation graph of Ballard et al. 6 Maternal and infant histories were surveyed for risk factors associated with hypoglycemia. All infants thought to be at increased risk for hypoglycemia were screened using Dextrostix, with interpretation by the Eyetone Reflectance Meter (Ames Co., Elkhart, Ind.). This method of interpretation is quantitative rather than semiquantita- tive, with an accuracy within _+ 5 mg/dl laboratory whole- blood glucose values. Dextrostix determinations were done within the first hour after birth, at 3 and 5 hours of age, and then prior to feeding for 24 hours. All other infants (without risk factors) were evaluated at 5 hours of age, prior to the first feeding. Dextrostix determinations were done by trained nurses, using careful technique in order to avoid errors previously reported/-9 The Eyetone meter was recalibrated every 8 hours, and calibration was rechecked prior to each use. If a Dextrostix glucose value of <40 mg/dl was obtained, a repeat estimation was done using a Dextrostix from a newly opened bottle. At the same time, hypoglycemia was confirmed by a heelstick serum glucose value run on an automated chemical analyzer (ACA-3) using standard technique and quality control. RESULTS During the study period, 232 babies were born. Of these, 168 (72%) had one or more of the risk factors for hypoglycemia. None of the 64 infants without risk factors was found to have hypoglycemia prior to the first feeding. Of those infants with a known risk factor, 120 did not have The Journal of PEDIATRICS Vol. 105, No. 1, July 1984 149