Prepregnancy BMI, gestational weight gain, and susceptibility to autism-related traits: the EARLI and HOME studies

Effect modification of pre-pregnancy body mass index on association of gestational weight gain with birth weight

Background

Maternal weight status, before or during pregnancy, is a significant determinant of fetus development, birth weight, and the short-term and long-term health outcomes of the offspring.

Objective

This study aimed to evaluate the effect modification of pre-pregnancy body mass index (BMI) on the associations of gestational weight gain (GWG) and birth weight, as per the latest guidelines from the Chinese Nutrition Society.

Methods

This is a retrospective cohort study performed in a tertiary hospital with the largest deliveries in Shanghai, China. This study included all women who had singleton live births from 2021 to 2022 (n = 50,391). Data on pre-pregnancy weight, GWG, and birth weight were extracted from the medical register system. Logistic regression models were used to estimate the associations of pre-pregnancy BMI and GWG with the risks of being small for gestational age (SGA) and large for gestational age (LGA). The potential for effect modification by BMI on the associations of GWG and birth weight was assessed using both additive and multiplicative scales.

Results

Pre-pregnancy BMI and GWG were consistently associated with birth weight. We observed a positive effect modification by underweight on the relationships between insufficient GWG and SGA both in multiplicative (adjusted odds ratio (OR), 2.49, 95 % confidence interval (CI): 2.06-2.99), and additive (relative excess risk due to interaction (RERI), 3.04, 95 % CI: 1.70-4.37) scales. Similarly, obesity was found to modify the effect of excessive GWG on the risk of LGA (adjusted OR, 3.82, 95 % CI, 3.14-4.63; RERI, 14.67, 95 % CI: 7.92-21.41).

Conclusion

Our findings indicate that increased GWG is associated with a higher risk of abnormal birth weight in singleton pregnancies. Additionally, there is evidence of an additive interaction between pre-pregnancy BMI and GWG on the risk of small for gestational age or large for gestational age.

Prenatal Programming of Monocyte Chemotactic Protein-1 Signaling in Autism Susceptibility

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that involves functional and structural defects in selective central nervous system (CNS) regions, harming the individual capability to process and respond to external stimuli, including impaired verbal and non-verbal communications. Etiological causes of ASD have not been fully clarified; however, prenatal activation of the innate immune system by external stimuli might infiltrate peripheral immune cells into the fetal CNS and activate cytokine secretion by microglia and astrocytes. For instance, genomic and postmortem histological analysis has identified proinflammatory gene signatures, microglia-related expressed genes, and neuroinflammatory markers in the brain during ASD diagnosis. Active neuroinflammation might also occur during the developmental stage, promoting the establishment of a defective brain connectome and increasing susceptibility to ASD after birth. While still under investigation, we tested the hypothesis whether the monocyte chemoattractant protein-1 (MCP-1) signaling is prenatally programmed to favor peripheral immune cell infiltration and activate microglia into the fetal CNS, setting susceptibility to autism-like behavior. In this review, we will comprehensively provide the current understanding of the prenatal activation of MCP-1 signaling by external stimuli during the developmental stage as a new selective node to promote neuroinflammation, brain structural alterations, and behavioral defects associated to ASD diagnosis.