Presented at the Neonatal Society 2011 Autumn Meeting.
Parkinson JRC, , Hyde MJ, Gale C, Santhakumaran S, Neena N. 2011
Imperial College London, 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. An increasing number of studies have sought a relationship between preterm birth and increased blood pressure in later life (1,2). We aimed to conduct a meta-analysis to address this association.
Methods: A literature search was conducted in Medline using pre-defined search terms. Studies were included if they measured blood pressure outcomes in adults (≥18 years) born preterm (<37 weeks gestational age (GA)) or term (38-41 weeks GA). Authors were contacted to obtain further information if required. Where studies were comparable in exposure definition and outcome measure, 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. Funnel plots and Egger’s test were performed to investigate publication bias.
Results: 208 papers were reviewed in full text with 31 eligible for inclusion in the review. The pooled unadjusted odds ratio (OR) for systolic blood pressure (SBP) and diastolic blood pressure (DBP) in ex-preterm and term control groups are shown in Table 1. Papers which supplied data on exclusively male or female subjects were included in gender specific analysis. Meta-regression analysis revealed a gender effect with ex-preterm women demonstrating significantly increased SBP (p=0.002) and DBP (p=0.05) compared to ex-preterm men. Funnel plots indicate significant asymmetry for both SBP and DBP (p<0.001 for both).
Figures: Meta-analysis results. CI: Confidence Interval; F/ RE: Fixed/Random Effects model
Conclusion: Our meta-analysis has shown that premature birth is associated with significantly increased systolic and diastolic blood pressure in adulthood. Larger effect sizes in smaller studies contributed to the asymmetry observed in funnel plots and results must therefore be interpreted accordingly. Our data indicates that individuals should be aware that if they were born preterm this may have potentially long-term adverse effects on blood pressure. Meta-analysis reveal that the increase in blood pressure is more pronounced in female ex-preterm subjects compared to male ex-preterms; a notable result given the accepted increased biological vulnerability of the male. The clinically relevant increase in SBP and DBP in preterm individuals is therefore of real concern.
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1. Thomas EL, Parkinson JRC, Hyde MJ, Yap IK, Holmes E, Dore CJ et al. Aberrant adiposity and ectopic lipid deposition characterise the adult phenotype of the preterm infant. Ped. Res 2011 Jul
2. Norman M. Preterm birth — an emerging risk factor for adult hypertension? Semin Perinatol 2010 June; 34(3):183-7