Presented at the Neonatal Society 2012 Spring Meeting.
Parkinson JRC, Hyde MJ, Gale C, Santhakumaran S, Modi N
Neonatal Medicine, Imperial College London, 369 Fulham Road, London, SW10 9NH, UK
Background: In the UK approximately 60,000 babies are born preterm (<37 weeks) annually and over 90% survive. With more infants reaching adulthood, the impact of prematurity upon long-term health is a matter of growing concern. Insulin resistance, increased waist circumference and fat mass have all been recorded in young adults born preterm (1). We conducted a meta-analysis to address these associations in adult life.
Methods: A literature search was conducted in Medline using pre-defined search terms. Studies were included if they measured outcomes in adults (≥18 years) born preterm (<37 weeks gestational age (GA)) or term (37+0- 41+6 weeks GA). The mean and standard deviation for preterm and term groups were extracted for the following parameters; 1) BMI (kg/m2); 2) Waist to Hip Ratio (WHR); 3) Percentage Fat Mass (%FM); Fasting levels of 4) Glucose (mmol/L); 5) Insulin (mU/L); 6) Cholesterol (mmol/L); 7) High Density Lipoprotein (mmol/L); 8) Low density Lipoprotein (mmol/L); 9) Triglycerides (mmol/L). Authors were contacted if further information was required. A meta-analysis was carried out in RevMan5 using the inverse variance method. Where heterogeneity was present a random effects meta-analysis was carried out, otherwise a fixed effects analysis was performed.
Results: 209 papers were reviewed in full text, with 24 eligible for inclusion in the review. Pooled unadjusted mean differences and 95% confidence intervals (CI) for selected outcomes are shown in Table 1. Papers which supplied data on exclusively male or female subjects were included in gender specific analysis. Ex-preterm adults demonstrated a significant increase in WHR (p=0.02, Table 1). Meta-regression revealed no significant gender effects. No significant differences were observed in other outcomes. Funnel plots indicate asymmetry for several parameters including BMI, and %FM in male subjects.
Table 1: Selected meta-analysis results
# number of studies; CI confidence interval; F / RE fixed effect/random effect model; PT preterm; SD standard deviation; TC term control; M male; F female
Conclusion: Previous studies indicate subjects born preterm remain shorter and lighter than their peers throughout childhood and adolescence; however, our analyses of BMI data suggest that by adulthood this difference has disappeared. Furthermore, we report a significantly greater WHR in preterm adults compared to term born controls. WHR is an anthropometric measure that correlates more closely with features of the metabolic syndrome than BMI and an increase is indicative of an alteration in adipose tissue distribution. Central adiposity may represent a key marker of the adverse metabolic phenotype of preterm adults and the increase in WHR is in agreement with our previous research demonstrating increased central adiposity and liver fat in ex-preterm male adults (1).
Corresponding author: jrcp@imperial.ac.uk
References
1. Thomas EL, et al. (2011) Pediatric Research 70:507-512