The objectives of this study were (1) to systematically review the literature on the association between birth weight in children born in the first and second generation and (2) to quantify this association by performing a meta-analysis. A systematic review was carried out in six databases (PubMed, Science Direct, Web of Science, Embase, Scopus, CINAHL and LILACS), in January 2021, for studies that recorded the birth weight of parents and children. A meta-analysis using random effects to obtain a pooled effect of the difference in birth weight and the association of low birth weight (LBW) between generations was performed. Furthermore, univariable meta-regression was conducted to assess heterogeneity. Egger’s tests were used to possible publication biases. Of the 9878 identified studies, seventy were read in full and twenty were included in the meta-analysis (ten prospective cohorts and ten retrospective cohorts), fourteen studies for difference in means and eleven studies for the association of LBW between generations (twenty-three estimates). Across all studies, there was no statistically significant mean difference (MD) birth weight between first and second generation (MD 19·26, 95 % CI 28·85, 67·36; P = 0·43). Overall, children of LBW parents were 69 % more likely to have LBW (pooled effect size 1·69, 95 % CI (1·46, 1·95); I 2:85·8 %). No source of heterogeneity was identified among the studies and no publication bias. The average birth weight of parents does not influence the average birth weight of children; however, the proportion of LBW among the parents seems to affect the offspring’s birth weight.

This study evaluated the association between ultra-processed foods (UPF) on serum IL-6 and to investigate the mediation role of adiposity. Participants were 524 adults from the EPITeen Cohort (Porto, Portugal) and 2888 participants from the 1982 Pelotas Birth Cohort (Pelotas, Brazil). Dietary intake was collected using FFQ when participants were 21 years of age in the EPITeen and 23 years in the Pelotas Cohort. Serum IL-6 and body fat mass were evaluated when participants were 27 and 30 years old in the EPITeen and Pelotas, respectively. Generalised linear models were fitted to test main associations. Mediation of body fat mass was estimated using G-computation. After adjustment for socio-economic and behaviour variables, among females from the EPITeen, the concentration of IL-6 (pg/ml) increased with increasing intake of UPF from 1·31 (95 % CI 0·95, 1·82) in the first UPF quartile to 2·20 (95 % CI 1·60, 3·01) and 2·64 (95 % CI 1·89, 3·69) for the third and fourth UPF quartiles, respectively. A similar result was found among males in the Pelotas Cohort, IL-6 increased from 1·40 (95 % CI 1·32, 1·49) in the first UPF quartile to 1·50 (95 % CI 1·41, 1·59) and 1·59 (95 % CI 1·49, 1·70) in the two highest UPF quartiles. The P-value for the linear trend was < 0·01 in both findings. The indirect effect through fat mass was NS. Our findings suggest that the consumption of UPF was associated with an increase in IL-6 concentration; however, this association was not explained by adiposity.