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Few studies have examined the adverse birth sizes of preconception exposure to organophosphate pesticides (OPs) in women undergoing in vitro fertilization (IVF). We investigated the relationship of preconception OP exposure with birth sizes among Chinese women undergoing IVF. This study included 302 couples seeking infertility treatment in the China National Birth Cohort Study, from Shanghai, China, who gave birth to singleton infants between 2018 and 2021. Clinical data were collected from medical records. We measured the concentrations of six nonspecific dialkyl phosphates (DAP) metabolites of OPs [diethylthiophosphate (DETP), diethylphosphate (DEP), diethyldithiophosphate (DEDTP), dimethyldithiophosphate (DMTP), dimethylphosphate (DMP), and dimethyldithiophosphate (DMDTP)] in maternal urine. DMDTP and DEDTP were precluded from further analyses due to the low detection rates. Generalized linear models (GLMs) and weighted quantile sum (WQS) regression analyses were performed to examine the individual and joint effects of OP exposures on gestational age, birth weight, body length, and ponderal index. Odder ratio (OR) of preterm birth were estimated using logistic regression models. Women in the highest as compared with lowest quartile of DEP had shorter gestational age (β = - 0.68; 95% CI = −1.24, −0.11). The association was modified by sex, with boys showing larger decreases in gestational age (β = - 0.86; 95% CI = −1.60, −0.13). No associations were found between other DAP metabolites and birth sizes. Results from linear models with individual DAP metabolites were corroborated by the WQS regression where DEP had the largest contribution to the overall mixture effect on gestational age (weight = 0.70). Moreover, DEP concentration was associated with an elevated risk of preterm birth (OR = 1.35, 95% CI = 1.11, 2.25). Preconception DEP concentration was associated with shortened gestational age and increased risk of preterm birth, and the association was more pronounced among boys than girls. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFAS) are believed to impair early neurodevelopment and disrupt thyroid hormone (TH) levels. However, there are limited epidemiological data on the neurodevelopmental effects in infancy of prenatal PFAS exposure and the potential mediating effects of TH. To evaluate potential associations between prenatal PFAS exposure and early neurodevelopmental deficiencies, and assess mediator effects of TH. From 2010 to 2013, 274 mother-infant pairs were recruited to the Laizhou Wan Birth Cohort in China. Ten PFAS and five TH were measured in cord serum. Developmental quotient (DQ) from 5 domains (adaptive, social, language, gross and fine motor) was assessed using Gesell Developmental Schedules for each child at 1 year of age. The associations between PFAS and DQs were evaluated using multivariable linear regressions. TH-mediated effects of PFAS on DQs were calculated by mediation analyses. Among our study population, PFAS exposures were common and associated with DQ decrement in infants. For each 10-fold increase in PFBS concentrations, gross motor and adaptive DQ decreased by 8.56 (95%CI: −15.15, −1.97) and 5.87 (95%CI: −8.07, −3.67) points, respectively. TSH mediated 12.90% of the association of PFBS with gross motor DQ and FT4 explained 19.63% of the association of PFBS with adaptive DQ. The negative association was also found between PFHxS exposure and gross motor DQ (β = 8.14, 95%CI: −15.39, −0.98). PFBS and PFHxS were negatively associated with early neurodevelopment, especially consistent in gross motor domain. The associations were partly explained by TSH and FT4. • The relationship between PFAS exposure, thyroid hormones and infant neurodevelopment were assessed in a Chinese birth cohort. • Prenatal PFHxS and PFBS exposure were associated with lower gross motor DQ, especially in males. • TSH and FT4 partly mediated the association of PFBS with DQ in several neurodevelopmental domains at 1 year of life. [ABSTRACT FROM AUTHOR]