Small for gestational age preterm infants and later adiposity and height: A systematic review and meta-analysis

BackgroundOverweight and obesity and their consequent morbidities are important worldwide health problems. Some research suggests excess adiposity origins may begin in fetal life, but unknown is whether this applies to infants born preterm. ObjectiveThe objective of the study was to assess the association between small for gestational age (SGA) birth and later adiposity and height among those born preterm. Data sourcesMEDLINE, EMBASE and CINAHL until October 2022. Study selection and data extractionStudies were included if they reported anthropometric (adiposity measures and height) outcomes for participants born preterm with SGA versus non-SGA. Screening, data extraction and risks of bias assessments were conducted in duplicate by two reviewers. SynthesisWe meta-analysed across studies using random-effects models and explored potential heterogeneity sources. ResultsThirty-nine studies met the inclusion criteria. In later life, preterm SGA infants had a lower body mass index (-0.66 kg/m(2), 95% CI -0.79, -0.53; 32 studies, I-2 = 16.7, n = 30,346), waist circumference (-1.20 cm, 95% CI -2.17, -0.23; 13 studies, I-2 = 19.4, n = 2061), lean mass (-2.62 kg, 95% CI -3.45, 1.80; 7 studies, I-2 = 0, n = 205) and height (-3.85 cm, 95% CI -4.73, -2.96; 26 studies, I-2 = 52.6, n = 4174) compared with those preterm infants born non-SGA. There were no differences between preterm SGA and preterm non-SGA groups in waist/hip ratio, body fat, body fat per cent, truncal fat per cent, fat mass index or lean mass index, although power was limited for some analyses. Studies were rated at high risk of bias due to potential residual confounding and low risk of bias in other domains. ConclusionsCompared to their preterm non-SGA peers, preterm infants born SGA have lower BMI, waist circumference, lean body mass and height in later life. No differences in adiposity were observed between SGA preterm infants and non-SGA preterm infants.