Background Historical reports suggest that infants born small for gestational age (SGA) are at increased risk for high blood pressure (BP) at older ages after adjustment for later age body size. Such adjustment may be inappropriate since adiposity is a known cause of cardiovascular and metabolic disease. Objectives To assess the association between SGA births and later BP among preterm births, considering potential background confounders and over‐adjustment for later body size. Methods A database search of studies up to October 2022 included MEDLINE, EMBASE and CINAHL. Studies were included if they reported BP (systolic [SBP] or diastolic [DBP]) (outcomes) for participants born preterm with SGA (exposure) or non‐SGA births. All screening, extraction steps, and risk of bias (using the Risk of Bias In Non‐randomised Studies of Interventions [ROBINS‐I] tool) were conducted in duplicate by two reviewers. Data were pooled in meta‐analysis using random‐effects models. We explored potential sources of heterogeneity. Results We found no meaningful difference in later BP between preterm infants with and without SGA status at birth. Meta‐analysis of 25 studies showed that preterm SGA, compared to preterm non‐SGA, was not associated with higher BP at age 2 and older with mean differences for SBP 0.01 mmHg (95% CI −0.10, 0.12, I2 = 59.8%, n = 20,462) and DBP 0.01 mm Hg (95% CI −0.10, 0.12), 22 studies, (I2 = 53.0%, n = 20,182). Adjustment for current weight did not alter the results, which could be due to the lack of differences in later weight status in most of the included studies. The included studies were rated to be at risk of bias due to potential residual confounding, with a low risk of bias in other domains. Conclusions Evidence indicates that preterm infants born SGA are not at increased risk of developing higher BP as children or as adults as compared to non‐SGA preterm infants.

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/m2, 95% CI −0.79, −0.53; 32 studies, I2 = 16.7, n = 30,346), waist circumference (−1.20 cm, 95% CI −2.17, −0.23; 13 studies, I2 = 19.4, n = 2061), lean mass (−2.62 kg, 95% CI −3.45, 1.80; 7 studies, I2 = 0, n = 205) and height (−3.85 cm, 95% CI −4.73, −2.96; 26 studies, I2 = 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.