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A growing body of literature suggests that cesarean delivery (CD) is associated with less optimal health outcomes in children (Kaeg et al., 2018; Cho et al., 2013), but the effects on child mental health have received considerably less attention. Nevertheless, CD may affect children’s psychological outcomes via altered gut microbiota (Rutayisire et al., 2016), re-programming of the HPA axis (Hyde et al., 2012), interrupted fetal brain maturation in elective cesarean deliveries (Kapellou, 2011) or psychological vulnerability in mothers after CD (Dekel et al., 2019). Several studies reported a higher risk of externalizing or internalizing problems in CD born babies (Jasiulione & Jusiene, 2019; Kelmanson, 2013), but the results are conflicting. Some studies found no association (Al Khalaf et al., 2015; Curran et al., 2016), while Li et al. (2011) observed a lower risk of externalizing problems in CD born children. The inconsistency in the existing research may be due to the different methodologies applied, especially regarding the inclusion of control variables, child's age when the outcome was assessed, methods used for measuring child outcomes, and sample characteristics. Moreover, while some studies assessed the effects of CD on maternal request (Huang et al., 2019; Kelmanson, 2013; Li et al., 2011), others reported the results related to CD planned for a medical reason or emergency CD (Al Khalaf et al., 2015; Curran et al., 2016; Jasiulione & Jusiene, 2019) or did not differentiate between different types of CD at all (Rutayisire et al., 2018). In addition, various moderating factors might play a paramount role. For example, infant gut colonization is affected not only by delivery mode but also to a large extent by breastfeeding (Pannaraj et al., 2017). Thus, CD and breastfeeding might interact to affect child mental health outcomes. Moreover, maternal prenatal stress has been linked to the altered maternal microbiome, with vaginal delivery considered a pathway that transmits maternal psychological stress to her offspring (Gur et al., 2017; Jasarevic et al., 2015). Consequently, CD might have differential effects on children whose mothers experienced high and low levels of stress while pregnant. Nevertheless, no study has examined such interactions to date. The proposed study aims to examine the moderating effects of breastfeeding and maternal prenatal stress on the association between CD and child externalizing and internalizing problems while distinguishing between planned and emergency CD and accounting for a wide range of relevant confounders (indications for CD; intrapartum interventions and medication, especially anesthesia and synthetic oxytocin; familial confounding; socioeconomic status; maternal life style and mental health). For this purpose, we are utilizing data from the Environmental Influences on Child Health Outcomes (ECHO) follow-up cohort of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies – Singletons, providing a large, racially/ethnically diverse sample of mother-child pairs.

Despite emerging evidence that the babies born via cesarean delivery (CD) have different hormonal, physical, and bacterial exposures that can affect their neurophysiology and neurodevelopment (Hyde et al., 2012), the studies on the effects of perinatal factors such as delivery mode are scarce. Between 1990 and 2014, the CD rate increased from 11% to 25% in Europe and from 22.3% to 32.3% in North America (Betrán et al., 2016). However, it was only in 2017 that the first detailed study on the link between CD and cognitive development appeared (Polidano, Zhu, & Bornstein, 2017), concluding that negative effects of CD on cognitive outcomes are large enough to warrant action. Few other studies focused on the association between CD and cognitive outcomes, observing intellectual difficulties (Gonzalez-Valenzuela et al., 2019) and slowed stimulus-driven, reflexive attention (Adler, 2015) in CS born babies. Similarly, the research on the association between delivery mode and motor development is sparse, with several studies indicating significant associations using maternal report (Al Khalaf et al., 2015), parental retrospective report (Chojnacki et al., 2019) and clinical assessment (Grace et al., 2016; Hands et al., 2009) of child’s motor abilities. The major weaknesses of the existing studies on the effects of CD on child cognitive and motor development include a prevailing reliance on parental report of children’s abilities and failure to examine the mechanisms through which CD might affect child outcomes and factors modulating this association. For example, CD was found to be associated with lower rates of breastfeeding (Pérez-Ríos et al., 2008), but only one study examined the mediating effect of breastfeeding on child cognitive outcomes (Polidano, Zhu, & Bornstein, 2017) and none on the motor outcomes. In the proposed study, we aim at examining the effects of CD on child executive functioning and motor development using observer-based ratings of the child and investigating the mediating/moderating role of breastfeeding status.

Maternal prenatal stress, including perceived stress, pregnancy specific worries, depression, and anxiety, has been associated with various childhood neurobehavioral outcomes in offspring such as increased risk for attention, behavior and emotion problems (Van den Bergh et al., 2017). In a longitudinal study, O'Donnell, Glover, Barker, and O'Connor (2014) demonstrated that greater maternal prenatal anxiety and depression were associated with a twofold increase in risk for child behavioral and emotional problems between 4 to 8 years of age. And yet, in this seminal work, child outcomes were based on maternal report, which was also the source of prenatal mood (Monk, Lugo-Candelas, & Trumpff, 2019). In a similar study, Szekely et al. (2020) replicated these findings across three longitudinal cohorts to show that elevated maternal prenatal mood and pregnancy specific worries were associated with child psychopathology at 4 to 8 years of age. Their outcome of child psychopathology was a factor derived from collated parent-, teacher- and child-reports — people all in interpersonal contact though one cohort also included field-worker observation on a measure of child behavioral attributes (Sallis et al., 2019). Although O'Donnell et al. (2014) and Szekely et al. (2020) present findings that are integral to understanding and providing evidence for associations between prenatal stress and child neurodevelopmental outcomes, their findings are based on samples that are predominantly homogeneous in terms of race/ethnic background, which limits their generalizability. In the present study, we are leveraging longitudinal data from the Environmental Influences on Child Health Outcomes cohort of the NICHD Fetal Growth Studies (ECHO-NICHD-FGS), a racially/ethnically diverse sample with maternal-report of prenatal stress, multiple standardized observational measures of childhood neurobehavioral outcomes, and repeat fetal assessments including measures of fetal growth velocity (FGV), to determine associations between maternal stress in pregnancy and child outcomes potentially mediated by standardized measurement in child development prior to birth. Specifically, we aim to establish associations between maternal prenatal stress and child neurobehavioral outcomes, mediated by fetal growth. If we find that FGV mediates the association between maternal prenatal stress and child neurobehavioral outcomes this would provide evidence for a biological marker of maternal prenatal stress effects prior to birth and further validate the association between maternal prenatal stress and child outcomes. The child neurobehavioral outcomes assessed, most as observational variables, include executive functioning, motor development, and psychiatric outcomes such as internalizing and externalizing problems and autism spectrum disorder. Maternal prenatal stress includes perceived stress and symptoms of depression. FGV measures and norms on this sample have been previously published (Grantz et al., 2018). We will also consider factors that may confound the association between maternal prenatal stress and child neurobehavioral outcomes such as maternal age, race/ethnicity, education, income, social support, and stress at time of child neurobehavioral assessment, as well as fetal exposure to smoking, child biological sex, mode of delivery, and gestational age at birth.

This paper uses the finite element method for numerical simulation and builds a transient global model to simulate polycrystalline silicon ingot growing process in CGsim software. The transient global model is verified through experiments. In addition, the influence of the width and height of the bottom of the side insulation on the temperature field, power consumption and melt-crystal interface (m/c interface) of the solidification process are analyzed. And a new hot zone design method is proposed to protect seed crystal silicon. The results show that the residual height of the seed crystal is increased by 4.5 mm through this design. And increasing the width and height of the side insulation bottom can effectively reduce the power consumption by 5 kW and improve the crystal growth interface, which helps to improve the crystal quality and reduce the cost. This study will provide some references for the optimization of polycrystalline silicon ingot growing process.