Fetal lung growth predicts the risk for early-life respiratory infections and childhood asthma.

BACKGROUND: Early-life respiratory infections and asthma are major health burdens during childhood. Markers predicting an increased risk for early-life respiratory diseases are sparse. Here, we identified the predictive value of ultrasound-monitored fetal lung growth for the risk of early-life respiratory infections and asthma. METHODS: Fetal lung size was serially assessed at standardized time points by transabdominal ultrasound in pregnant women participating in a pregnancy cohort. Correlations between fetal lung growth and respiratory infections in infancy or early-onset asthma at five years were examined. Machine-learning models relying on extreme gradient boosting regressor or classifier algorithms were developed to predict respiratory infection or asthma risk based on fetal lung growth. For model development and validation, study participants were randomly divided into a training and a testing group, respectively, by the employed algorithm. RESULTS: Enhanced fetal lung growth throughout pregnancy predicted a lower early-life respiratory infection risk. Male sex was associated with a higher risk for respiratory infections in infancy. Fetal lung growth could also predict the risk of asthma at five years of age. We designed three machine-learning models to predict the risk and number of infections in infancy as well as the risk of early-onset asthma. The models' R2 values were 0.92, 0.90 and 0.93, respectively, underscoring a high accuracy and agreement between the actual and predicted values. Influential variables included known risk factors and novel predictors, such as ultrasound-monitored fetal lung growth. CONCLUSION: Sonographic monitoring of fetal lung growth allows to predict the risk for early-life respiratory infections and asthma.

Pregnancy-induced transfer of pathogen-specific T cells from mother to fetus in mice.

Neonatal health is determined by the transfer of maternal antibodies from the mother to the fetus. Besides antibodies, maternal cells cross the placental barrier and seed into fetal organs. Contrary to maternal antibodies, maternal microchimeric cells (MMc) show a high longevity, as they can persist in the offspring until adulthood. Recent evidence highlights that MMc leukocytes promote neonatal immunity against early-life infections in mice and humans. As shown in mice, this promotion of immunity was attributable to an improved fetal immune development. Besides this indirect effect, MMc may be pathogen-specific and thus, directly clear pathogen threats in the offspring postnatally. By using ovalbumin recombinant Listeria monocytogenes (LmOVA), we here provide evidence that OVA-specific T cells are transferred from the mother to the fetus, which is associated with increased activation of T cells and a milder course of postnatal infection in the offspring. Our data highlight that maternally-derived passive immunity of the neonate is not limited to antibodies, as MMc have the potential to transfer immune memory between generations.

Experience of early motherhood during the first wave of the COVID-19 pandemic in Northern Germany: a single-centre before and after comparison.

PURPOSE: To assess maternal mental health during the first weeks after birth including birth experience, postpartum adjustment to early motherhood and the perception of newborn behaviour, and how this may be influenced by the first wave of the COVID-19 pandemic. METHODS: Ninety women who gave birth after the first enforcement of nation-wide disease control restrictions in Germany between 16 March and 10 May 2020 were surveyed and compared with 101 women who had given birth before the pandemic. Information on maternal mental health and maternal perception of early motherhood and neonatal behaviour were assessed at 3-8 weeks postpartum. RESULTS: Mothers who gave birth under the COVID-19-associated disease control restrictions did not show significant differences in depression, anxiety and social support scales compared to mothers before the pandemic. Birth experience was similar, while support during birth was perceived to be higher under the COVID-19 restrictions. Confidence in caretaking of the newborn and perception of neonatal behaviour were comparable between the two groups. Mothers expressed significantly higher dissatisfaction with the maternal role during the pandemic. CONCLUSIONS: Overall, maternal mental health and the perception of the newborn and early caretaking during the first COVID-19 wave did not substantially differ from the perceptions of mothers before the pandemic. A potential influence of the pandemic on higher dissatisfaction with the maternal role may be associated with the pandemic conditions affecting everyday life and should be addressed in postpartum care and in future qualitative and longitudinal studies.

Pregnancy-induced maternal microchimerism shapes neurodevelopment and behavior in mice.

Life-long brain function and mental health are critically determined by developmental processes occurring before birth. During mammalian pregnancy, maternal cells are transferred to the fetus. They are referred to as maternal microchimeric cells (MMc). Among other organs, MMc seed into the fetal brain, where their function is unknown. Here, we show that, in the offspring's developing brain in mice, MMc express a unique signature of sensome markers, control microglia homeostasis and prevent excessive presynaptic elimination. Further, MMc facilitate the oscillatory entrainment of developing prefrontal-hippocampal circuits and support the maturation of behavioral abilities. Our findings highlight that MMc are not a mere placental leak out, but rather a functional mechanism that shapes optimal conditions for healthy brain function later in life.

Vertically transferred maternal immune cells promote neonatal immunity against early life infections.

During mammalian pregnancy, immune cells are vertically transferred from mother to fetus. The functional role of these maternal microchimeric cells (MMc) in the offspring is mostly unknown. Here we show a mouse model in which MMc numbers are either normal or low, which enables functional assessment of MMc. We report a functional role of MMc in promoting fetal immune development. MMc induces preferential differentiation of hematopoietic stem cells in fetal bone marrow towards monocytes within the myeloid compartment. Neonatal mice with higher numbers of MMc and monocytes show enhanced resilience against cytomegalovirus infection. Similarly, higher numbers of MMc in human cord blood are linked to a lower number of respiratory infections during the first year of life. Our data highlight the importance of MMc in promoting fetal immune development, potentially averting the threats caused by early life exposure to pathogens.

Born Under COVID-19 Pandemic Conditions: Infant Regulatory Problems and Maternal Mental Health at 7 Months Postpartum.

BACKGROUND: The SARS-COVID-19 pandemic and its associated disease control restrictions have in multiple ways affected families with young children, who may be especially vulnerable to mental health problems. Studies report an increase in perinatal parental distress as well as symptoms of anxiety or depression in children during the pandemic. Currently, little is known about the impact of the pandemic on infants and their development. Infant regulatory problems (RPs) have been identified as early indicators of child socio-emotional development, strongly associated with maternal mental health and the early parent-infant interaction. Our study investigates whether early parenthood under COVID-19 is associated with more maternal depressive symptoms and with a perception of their infants as having more RPs regarding crying/fussing, sleeping, or eating, compared to mothers assessed before the pandemic. METHODS: As part of a longitudinal study, 65 women who had given birth during the first nationwide disease control restrictions in Northern Germany, were surveyed at 7 months postpartum and compared to 97 women assessed before the pandemic. RPs and on maternal depressive symptoms were assessed by maternal report. Number of previous children, infant negative emotionality, and perceived social support were assessed as control variables. RESULTS: Compared to the control cohort, infants born during the COVID-19 pandemic and those of mothers with higher depressive symptoms were perceived as having more sleeping and crying, but not more eating problems. Regression-based analyses showed no additional moderating effect of parenthood under COVID-19 on the association of depressive symptoms with RPs. Infant negative emotionality was positively, and number of previous children was negatively associated with RPs. LIMITATIONS: Due to the small sample size and cross-sectional assessment, the possibility for more complex multivariate analysis was limited. The use of parent-report questionnaires to assess infant RPs can support but not replace clinical diagnosis. CONCLUSIONS: The pandemic conditions affecting everyday life may have a long-term influence on impaired infant self- and maternal co-regulation and on maternal mental health. This should be addressed in peripartum and pediatric care. Qualitative and longitudinal studies focusing on long-term parental and infant outcomes under ongoing pandemic conditions are encouraged.

Prenatal Immune and Endocrine Modulators of Offspring's Brain Development and Cognitive Functions Later in Life.

Milestones of brain development in mammals are completed before birth, which provide the prerequisite for cognitive and intellectual performances of the offspring. Prenatal challenges, such as maternal stress experience or infections, have been linked to impaired cognitive development, poor intellectual performances as well as neurodevelopmental and psychiatric disorders in the offspring later in life. Fetal microglial cells may be the target of such challenges and could be functionally modified by maternal markers. Maternal markers can cross the placenta and reach the fetus, a phenomenon commonly referred to as "vertical transfer." These maternal markers include hormones, such as glucocorticoids, and also maternal immune cells and cytokines, all of which can be altered in response to prenatal challenges. Whilst it is difficult to discriminate between the maternal or fetal origin of glucocorticoids and cytokines in the offspring, immune cells of maternal origin-although low in frequency-can be clearly set apart from offspring's cells in the fetal and adult brain. To date, insights into the functional role of these cells are limited, but it is emergingly recognized that these maternal microchimeric cells may affect fetal brain development, as well as post-natal cognitive performances and behavior. Moreover, the inheritance of vertically transferred cells across generations has been proposed, yielding to the presence of a microchiome in individuals. Hence, it will be one of the scientific challenges in the field of neuroimmunology to identify the functional role of maternal microchimeric cells as well as the brain microchiome. Maternal microchimeric cells, along with hormones and cytokines, may induce epigenetic changes in the fetal brain. Recent data underpin that brain development in response to prenatal stress challenges can be altered across several generations, independent of a genetic predisposition, supporting an epigenetic inheritance. We here discuss how fetal brain development and offspring's cognitive functions later in life is modulated in the turnstile of prenatal challenges by introducing novel and recently emerging pathway, involving maternal hormones and immune markers.