Background: Increased survival of extremely low birth infants due to advances in antenatal and neonatal care has resulted in a population of infants at high risk of developing retinopathy of prematurity (ROP). Therapeutic interventions include the use of antenatal and postnatal steroids however, their effects on the severity of ROP is in dispute. In addition, it has not been investigated whether severe ROP is due to therapeutic interventions or due to the severity of illness. The aim of the present study was to assess the association between the incidence of severe retinopathy of prematurity (greater than stage 2 -International classification of ROP) and mechanical ventilation, oxygen therapy, gestational age, antenatal and postnatal steroids in extremely low birth weight infants.

Great Lakes sport-caught fish are contaminated with various organochlorines (OCs) such as polychlorinated biphenyls (PCBs). Through consumption of these fish, humans are subject to continuing levels of OC contamination. To assess potential adverse effects of past exposure, we compared three different backward extrapolation models. The data originated from OC determinations in a cohort of anglers and their families. Repeated PCB measurements collected in the 1970s, 1980s, and 1990s were used when testing the backward extrapolations. We applied a simple and a complex decay model based on assumptions used in previous studies; a third was a regression model incorporating markers of OC intake and loss. These techniques provided past exposure estimates. Intraclass correlation coefficients (ICCs) were calculated comparing measured and estimated PCB values. ICC values for the regression model equations were 0.77 and 0.89; ICC values for the simple and complex decay models were significantly lower, with ranges of 0.07-0.45 and -0.14-0.69, respectively. Plots showing trends of OC concentrations in fish and humans indicate comparable increases and decreases of PCB in fish and humans, with fish concentrations peaking approximately 10 years before that in humans. Our findings suggest that one should be cautious when using simple backward extrapolation techniques to estimate OC exposure in situations involving changing environmental exposures. Whenever repeated measurements are available, regression analyses seem to produce more accurate backward estimations of exposure.

Reference data describing weight, length, and head circumference (anthropometric measurements) at birth were published by Lubchenco and Usher before 1970. Few attempts have been made to investigate whether these data are appropriate for today's cohort of preterm neonates. We analysed anthropometric data for neonates born between 23 and 29 weeks' gestation. Reference charts were developed from the measurements obtained from neonatal records, and gestational age, obtained from maternal charts, on 975 neonates delivered at four neonatal centres in Michigan during 1992 and 1997. The analysis was confined to children with gestational age that was consistent or within 7 days by last menstrual period, obstetric examination, ultrasound and neonatal determinations. At 23 to 29 weeks' gestation, ethnicity and multiple births did not have any significant impact on birthweight but girls were lighter. We compared our anthropometric charts with those presently being used at many neonatal centres. In our study, physical measurements at birth of preterm neonates born between 1992 and 1997 were significantly different from those currently used to assess growth status. Furthermore data derived from published studies that utilised birth certificates with gestational age based on last menstrual period seem to overestimate birthweight. For preterm infants, our findings are concordant with recently published values from 18 states of the US. Because of improved survival, gestational age assessment and perinatal care of preterm neonates, development of new reference anthropometric measurements for neonates is overdue. Our Michigan data of 23-29 weeks preterm provides new national reference values, which we recommend for use in US neonatal centres for extremely preterm neonates.