Prevalence of autism spectrum disorder diagnosis by birth weight, gestational age, and size for gestational age: a systematic review, meta-analysis, and meta-regression.

We aimed to comprehensively pool the prevalence of autism spectrum disorder (ASD) diagnosis by birth weight, gestational age, and size for gestational age. PubMed, EMBASE, Web of Science, Ovid PsycINFO, and Cochrane Library were searched up to December 22, 2021. We pooled data using the random-effects model and quantified heterogeneity using the I2 statistic. Of 66 643 records initially identified, 75 studies were included in the meta-analysis. The pooled prevalence estimates of ASD diagnosis are as follows: very-low-birth weight, 3.1% (912 ASD/66,445 individuals); low-birth weight, 2.3% (5672 ASD/593,927 individuals); normal-birth weight, 0.5% (17,361 ASD/2,378,933 individuals); high-birth weight, 0.6% (4505 ASD/430,699 individuals); very preterm, 2.8% (2113 ASD/128,513 individuals); preterm, 2.1% (19 672 ASD/1 725 244 individuals); term, 0.6% (113,261 ASD/15,297,259 individuals); postterm, 0.6% (9419 ASD/1,138,215 individuals); small-for-gestational-age, 1.9% (6314 ASD/796,550 individuals); appropriate-for-gestational-age, 0.7% (21,026 ASD/5,936,704 individuals); and large-for-gestational-age, 0.6% (2607 ASD/635,666 individuals). Compared with the reference prevalence (those in normal-birth weight, term, and appropriate-for-gestational-age individuals), the prevalence estimates of ASD diagnosis in very-low-birth weight, low-birth weight, very preterm, preterm, and small-for-gestational-age individuals increased significantly, while those in high-birth weight, postterm, and large-for-gestational-age individuals did not change significantly. There were geographical differences in the prevalence estimates. This meta-analysis provided reliable estimates of the prevalence of ASD diagnosis by birth weight, gestational age, and size for gestational age, and suggested that low-birth weight (especially very-low-birth weight), preterm (especially very preterm), and small-for-gestational-age births, rather than high-birth weight, postterm, and large-for-gestational-age births, were associated with increased risk of ASD diagnosis. However, in view of marked between-study heterogeneity in most conditions, unknown effects of certain important confounders associated with ASD due to limited information in original articles, and included studies from a relatively small number of countries, the findings of this study should be interpreted with caution.

Association of maternal prenatal folic acid intake with subsequent risk of autism spectrum disorder in children: A systematic review and meta-analysis.

BACKGROUND: A number of studies have explored the link of antenatal folic acid (FA) intake with autism spectrum disorder (ASD) in children, with inconsistent findings. Therefore, we conducted a systematic review and meta-analysis of relevant studies to elucidate the actual association between maternal FA intake during the prenatal period and the risk of ASD in offspring. METHODS: PubMed, EMBASE, PsycINFO, Scopus, Web of Science, and Cochrane Library were searched up to June 7, 2018, without language restriction. The random-effects model was applied to summarize results. The adjusted odds ratios (ORs) and hazard ratios (HRs) were pooled separately. RESULTS: Eight observational studies (a total of 13 reports; 840,776 children and 7127 cases) were included. FA intake was mainly estimated from self-report of mothers or available databases. The results of overall analysis from 6 studies (9 reports) combined by OR and 2 studies (4 reports) presenting HR showed that the likelihoods of ASD in offspring whose mothers were prenatally exposed to FA did not vary significantly compared with those in offspring of mothers without such exposure (OR = 0.91, 95% CI: 0.73-1.13 and HR = 0.66, 95% CI: 0.38-1.17, respectively). Further analysis revealed that the primary outcome of the meta-analysis was stable regardless of the study design, and not unduly affected by any single report. Additionally, no publication bias was observed, and the findings of overall analysis were in agreement with those of subgroup analyses. CONCLUSIONS: This study does not provide support for the association between maternal FA intake during the prenatal period and the reduced risk of ASD in children. However, in view of the types and limited number of studies in the literature, more investigation is needed to confirm the findings of this meta-analysis.

Maternal multivitamin supplementation is associated with a reduced risk of autism spectrum disorder in children: a systematic review and meta-analysis.

Several studies have explored the link of antenatal multivitamin supplementation with autism spectrum disorder (ASD) in offspring, but the findings are inconsistent. The purpose of the current study was to perform a systematic review and meta-analysis of published studies to evaluate the actual association between maternal multivitamin supplementation during the prenatal period and the risk of ASD in children. PubMed, EMBASE, PsycINFO, Web of Science, and Cochrane Library were searched up to August 26, 2018. The random-effects model was used to calculate the pooled results. The adjusted risk ratios (RRs) were used as the common measure of association among studies. Sensitivity and subgroup analyses were also conducted. A total of 5 articles (9 independent trials; 231 163 children encompassing 4459 cases) were included. The results of overall analysis showed that the likelihood of ASD in offspring whose mothers used multivitamin supplements during the prenatal period was significantly reduced compared with that in offspring of mothers without such supplementation (RR, 0.62; 95% CI, 0.45-0.86; P = .003). Additionally, the primary outcome of the meta-analysis was quite robust after being verified by sensitivity analyses and no publication bias was found. Furthermore, the findings of overall analysis were generally consistent with those of subgroup analyses. In conclusion, this meta-analysis supports a protective association between maternal multivitamin supplementation during the prenatal period and the subsequent risk of ASD in children. Further investigation is needed and should address the constituent(s) contributing to the protective effect of multivitamin on ASD risk and the underlying molecular mechanisms.