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ABSTRACT The postpartum period represents a dynamic time for women’s health, particularly when it comes to changes in weight, which can disproportionately affect Latina women. Weight change, particularly weight gain, has been associated with pronounced changes in host gut microbiome profiles and composition. This study aimed to evaluate changes in the gut microbiome among Latina mothers who gained or lost weight in the first 6 months after delivery by characterizing changes in gut microbial co-occurrence networks, alpha- and beta-diversity measures, and relative abundances of bacterial taxa. This study characterized the gut microbiomes of 105 Latina mothers at 1 and 6 months postpartum, comparing mothers who gained weight (n = 65) with those who lost weight (n = 40) during the 6-month period following delivery. Stool samples were collected for 16S rRNA gene sequencing. Statistical analysis was conducted using microbial co-occurrence network analysis as well as paired two-sided t-tests. Mothers who gained weight postpartum had significant changes in their co-occurrence network density, alpha- and beta-diversity, and relative abundances of certain microbial taxa compared to those who lost weight. Microbial co-occurrence networks, representing measures of differences in community structure dynamics, of the weight gain group decreased in density by 2%, while there was no change in density in the weight loss group. Additionally, the weight gain group had lower Shannon entropy after 6 months and significant changes in the relative abundances of 17 bacterial families and genera, while there were no significant changes in any of these metrics in the weight loss group.IMPORTANCEPrevious research has reported differences in the gut microbiome associated with varying body compositions. More specifically, within populations of mothers, the focus has been on the impact of gestational weight gain. This is the first study to examine postpartum weight change and its association with changes in the gut microbiome, similarly, it is the first to use a Latina cohort to do so. The results support the idea that weight gain may be an important factor in reducing gut microbiome network connectivity, diversity, and changing abundances of specific microbial taxa, all measures thought to impact host health. These results suggest that weight gain dynamically alters mothers’ gut microbial communities in the first 6 months postpartum, with comparatively little change in mothers who lost weight; further research is needed to examine the health consequences of such changes.

Abstract Background Higher prenatal ambient air pollution exposure has been associated with impaired neurodevelopment in preschoolers and school-aged children. The purpose of this study was to explore the relationships between prenatal ambient air pollution exposure and neurodevelopment during infancy. Methods This study examined 161 Latino mother-infant pairs from the Southern California Mother’s Milk Study. Exposure assessments included prenatal nitrogen dioxide (NO2) and particulate matter smaller than 2.5 and 10 microns in diameter (PM2.5 and PM10, respectively). The pregnancy period was also examined as three windows, early, mid, and late, which describe the first, middle, and last three months of pregnancy. Infant neurodevelopmental outcomes at 2 years of age were measured using the Bayley-III Scales of Infant and Toddler Development. Multivariable linear models and distributed lag linear models (DLM) were used to examine relationships between prenatal exposures and neurodevelopmental scores, adjusting for socioeconomic status, breastfeeding frequency, time of delivery, pre-pregnancy body mass index, and infant birthweight and sex. Results Higher prenatal exposure to PM10 and PM2.5 was negatively associated with composite cognitive score (β = -2.01 [-3.89, -0.13] and β = -1.97 [-3.83, -0.10], respectively). In addition, higher average prenatal exposure to PM10 was negatively associated with composite motor (β = -2.35 [-3.95, -0.74]), scaled motor (β = -0.77 [-1.30, -0.24]), gross motor (β = -0.37 [-0.70, -0.04]), fine motor (β = -0.40 [-0.71, -0.09]), composite language (β = -1.87 [-3.52, -0.22]), scaled language (β = -0.61 [-1.18, -0.05]) and expressive communication scaled scores (β = -0.36 [-0.66, -0.05]). DLMs showed that higher prenatal air pollution exposure during mid and late pregnancy was inversely associated with motor, cognitive, and communication language scores. Conclusions Higher exposure to air pollutants during pregnancy, particularly in the mid and late prenatal periods, was inversely associated with scaled and composite motor, cognitive, and language scores at 2 years. These results indicate that prenatal ambient air pollution may negatively impact neurodevelopment in early life.