Defects in placental syncytiotrophoblast cells are a common cause of developmental heart disease.

Placental abnormalities have been sporadically implicated as a source of developmental heart defects. Yet it remains unknown how often the placenta is at the root of congenital heart defects (CHDs), and what the cellular mechanisms are that underpin this connection. Here, we selected three mouse mutant lines, Atp11a, Smg9 and Ssr2, that presented with placental and heart defects in a recent phenotyping screen, resulting in embryonic lethality. To dissect phenotype causality, we generated embryo- and trophoblast-specific conditional knockouts for each of these lines. This was facilitated by the establishment of a new transgenic mouse, Sox2-Flp, that enables the efficient generation of trophoblast-specific conditional knockouts. We demonstrate a strictly trophoblast-driven cause of the CHD and embryonic lethality in one of the three lines (Atp11a) and a significant contribution of the placenta to the embryonic phenotypes in another line (Smg9). Importantly, our data reveal defects in the maternal blood-facing syncytiotrophoblast layer as a shared pathology in placentally induced CHD models. This study highlights the placenta as a significant source of developmental heart disorders, insights that will transform our understanding of the vast number of unexplained congenital heart defects.

The Influence of Exercise-Associated Small Extracellular Vesicles on Trophoblasts In Vitro.

Exercise induces the release of small extracellular vesicles (sEVs) into circulation that are postulated to mediate tissue cross-talk during exercise. We previously reported that pregnant individuals released greater levels of sEVs into circulation after exercise compared to matched non-pregnant controls, but their biological functions remain unknown. In this study, sEVs isolated from the plasma of healthy pregnant and non-pregnant participants after a single bout of moderate-intensity exercise were evaluated for their impact on trophoblasts in vitro. Exercise-associated sEVs were found localized within the cytoplasm of BeWo choriocarcinoma cells, used to model trophoblasts in vitro. Exposure to exercise-associated sEVs did not significantly alter BeWo cell proliferation, gene expression of angiogenic growth factors VEGF and PLGF, or the release of the hormone human chorionic gonadotropin. The results from this pilot study support that exercise-associated sEVs could interact with trophoblasts in vitro, and warrant further investigation to reveal their potential role in communicating the effects of exercise to the maternal-fetal interface.

Impact of acute moderate-intensity aerobic exercise on circulating extracellular vesicles in pregnant and non-pregnant women.

Exercise improves cardiovascular and metabolic health in pregnancy and may represent a non-pharmacological approach to improving pregnancy outcomes. Extracellular vesicles (EVs) are emerging biomarkers of endothelial dysfunction and offer the potential for evaluating vascular health non-invasively during pregnancy. The purpose of this study was to investigate changes in circulating EV levels after an acute bout of moderate-intensity aerobic exercise in healthy pregnant and non-pregnant women. We studied plasma samples from pregnant (N = 13, 13-28 weeks) and non-pregnant (N = 17) women. A pre-exercise blood sample was obtained followed by a 30 min bout of moderate-intensity treadmill-based exercise. Immediately following the exercise, a post-exercise blood draw was collected. Large EVs were isolated from plasma by differential centrifugation and characterized by Western blot and electron microscopy. We quantified circulating EVs by nanoscale flow cytometry. Endothelial EVs were identified as VE-Cadherin+, platelet EVs as CD41+, and leukocyte EVs as CD45+ events. Acute exercise was associated with a significant reduction in levels of circulating endothelial EVs in the non-pregnant group (p = 0.0232) but not in the pregnant group (p = 0.2734). A greater proportion of non-pregnant women (13/17, 76.47%) exhibited a reduction in endothelial EVs compared with their pregnant counterparts (4/13, 30.76%, p < 0.05). We also observed a positive association between measures of fitness (average speed) and baseline levels of platelet (r = 0.5816, p = 0.0159) and total EVs (r = 0.5325, p = 0.0296) in the non-pregnant group but not in pregnant individuals. Collectively, our study highlights that after a matched acute exercise, changes to circulating EV levels differ depending on pregnancy status.

Circulating small extracellular vesicles increase after an acute bout of moderate-intensity exercise in pregnant compared to non-pregnant women.

The physiological and molecular mechanisms linking prenatal physical activity and improvements in maternal-fetal health are unknown. It is hypothesized that small extracellular vesicles (EVs, ~ 10-120 nm) are involved in tissue cross-talk during exercise. We aimed to characterize the circulating small EV profile of pregnant versus non-pregnant women after an acute bout of moderate-intensity exercise. Pregnant (N = 10) and non-pregnant control (N = 9) women performed a single session of moderate-intensity treadmill walking for 30 min. Plasma was collected immediately pre- and post-exercise, and small EVs were isolated by differential ultracentrifugation. EV presence was confirmed by western blotting for the small EV proteins TSG-101 and flottilin-1. Small EVs were quantified by size and concentration using nanoparticle tracking analysis and transmission electron microscopy. All EV fractions were positive for TSG-101 and flotillin-1, and negative for calnexin. Mean vesicle size at baseline and percent change in size post-exercise were not different between groups. At baseline, pregnant women had higher levels of small EVs compared to controls (1.83E+10 ± 1.25E+10 particles/mL vs. 8.11E+09 ± 4.04E+09 particles/mL, respectively; p = 0.032). Post-exercise, small EVs increased significantly in the circulation of pregnant compared to non-pregnant women after correcting for baseline values (64.7 ± 24.6% vs. - 23.3 ± 26.1%, respectively; F = 5.305, p = 0.035). Further research is needed to assess the functional roles of exercise-induced small EVs in pregnancy.

Does exercise during pregnancy impact organs or structures of the maternal-fetal interface?

Exercise during pregnancy has been shown to be associated with improved health outcomes both during and after pregnancy for mother and fetus across the lifespan. Increasing physical activity and reducing sedentary behaviour during pregnancy have been recommended by many researchers and clinicians-alike. It is thought that the placenta plays a central role in mediating any positive or negative pregnancy outcomes. The positive outcomes obtained through prenatal exercise are postulated to result from exercise-induced regulation of maternal physiology and placental development. Considerable research has been performed to understand the placenta's role in pregnancy-related diseases, such as preeclampsia, fetal growth restriction, and gestational diabetes mellitus. However, little research has examined the potential for healthy lifestyle and behavioural changes to improve placental growth, development, and function. While the placenta represents the critical maternal-fetal interface responsible for all gas, nutrient, and waste exchange between the mother and fetus, the impact of exercise during pregnancy on placental biology and function is not well known. This review will focus on prenatal exercise and its promising influence on the structures of the maternal-fetal interface, with particular emphasis on the placenta. Potential molecular mechanistic hypotheses are presented to aid future investigations of prenatal exercise and placental health.

How Many Valid Days Are Necessary to Assess Physical Activity Data From Accelerometry During Pregnancy?

BACKGROUND: The authors examined whether or not ≤3 days wearing Actical® accelerometers provided acceptable results in comparison with the recommendation of ≥4 days in women across gestation. METHODS: A total of 26, 76, and 57 participants at early, mid, and late pregnancy, respectively, were assessed. Participants were instructed to wear the device for 7 days and women who wore it for ≥4 days were included. For each participant, 3, 2, and 1 day(s) were randomly selected. Paired comparisons, intraclass correlations coefficients, and kappa statistics were performed for ≥4 days (criterion) versus 3, 2, and 1 day(s). Averages (in minutes per day) of sedentary time, light, moderate, vigorous, moderate to vigorous physical activity (PA) and steps per day were examined. RESULTS: When 3 valid days were compared with the criterion, no significant differences were found for any gestational period. The intraclass correlations coefficients were "high" for all PA-related variables. The k values varied from .819 to .838 across pregnancy ("strong"). Two and 1 valid day(s) versus the criterion showed significant differences in some PA intensities, reduced intraclass correlations coefficients, "moderate" k values for 2 valid days (.638-.788) and "minimal-to-moderate" k values for 1 valid day (.367-.755). CONCLUSION: In pregnant women during early, mid, and late pregnancy, PA data obtained from 3 valid days of wear was equivalent and agreed with ≥4 valid days.

Maternal and Cord Blood Metabolite Associations with Gestational Weight Gain and Pregnancy Health Outcomes.

Pre-pregnancy obesity and excessive gestational weight gain (GWG) are risk factors for future maternal and childhood obesity. Maternal obesity is potentially communicated to the fetus in part by the metabolome, altering the child's metabolic program in early development. Fasting maternal blood samples from 37 singleton pregnancies at 25-28 weeks of gestation were obtained from mothers with pre-pregnancy body mass indexes (BMIs) between 18 and 40 kg/m2. Various health measures including GWG, diet, and physical activity were also assessed. At term (37-42 weeks), a venous umbilical cord sample was obtained. Serum metabolomic profiles were measured using nuclear magnetic resonance spectroscopy as well as a gut and metabolic hormone panel. Maternal and cord serum metabolites were tested for associations with pre-pregnancy BMI, GWG, health outcomes, and gut and metabolic hormones. While cord blood metabolites showed no significant correlation to maternal obesity status or other measured health outcomes, maternal serum metabolites showed distinct profiles for lean, overweight, and obese women. Additionally, four serum metabolites, namely, glutamate, lysine, pyruvate, and valine, allowed prediction of excessive GWG when pre-pregnancy BMI was controlled. Metabolic biomarkers predictive of GWG are reported and, if validated, could aid in the guidance of prenatal weight management plans as the majority of pregnancy weight gain occurs in the third trimester.

Physical activity differentially regulates VEGF, PlGF, and their receptors in the human placenta.

Physical activity (PA) has beneficial effects on the function of many organs by modulating their vascular development. Regular PA during pregnancy is associated with favorable short- and long-term outcomes for both mother and fetus. During pregnancy, appropriate vascularization of the placenta is crucial for adequate maternal-fetal nutrient and gas exchange. How PA modulates angiogenic factors, VEGF, and its receptors in the human placenta, is as of yet, unknown. We objectively measured the PA of women at 24-28 and 34-38 weeks of gestation. Participants were considered "active" if they had met or exceeded 150 min of moderate-intensity PA per week during their 2nd trimester. Term placenta tissues were collected from active (n = 23) or inactive (n = 22) women immediately after delivery. We examined the expression of the angiogenic factors VEGF, PlGF, VEGFR-1, and VEGFR-2 in the placenta. Western blot analysis showed VEGF and its receptor, VEGFR-1 was significantly (p < 0.05) higher both at the protein and mRNA levels in placenta from physically active compared to inactive women. No difference in VEGFR-2 was observed. Furthermore, immunohistochemistry showed differential staining patterns of VEGF and its receptors in placental endothelial, stromal, and trophoblast cells and in the syncytial brush border. In comparison, PlGF expression did not differ either at the protein or mRNA level in the placenta from physically active or inactive women. The expression and localization pattern of VEGF and its receptors suggest that PA during pregnancy may support a pro-angiogenic milieu to the placental vascular network.

Physical activity may be an adjuvant treatment option for substance use disorders during pregnancy: A scoping review.

BACKGROUND: Substance abuse in pregnancy increases the chance of physical and neurobehavioral disabilities as well as many other undesirable fetal outcomes. In nonpregnant populations, physical exercise has shown to be an effective adjunctive therapy option for substance use disorders. Given the known positive maternal and fetal physiological and mental health benefits associated with prenatal exercise, perhaps exercise during pregnancy may also be a viable adjuvant therapy option for women with substance use disorders. The purpose of this scoping review was to summarize the available literature that has assessed the relationship between prenatal exercise and substance use disorders. METHODS: A search strategy was developed combining the terms pregnancy, exercise/physical activity, and substance use. A systematic search was completed in the following databases: Medline/PubMed, SPORTDiscus, and ProQuest. Substances eligible for inclusion included illicit drugs, alcohol, and cannabis. Retrieved data were categorized as animal or human model studies, and were summarized narratively. RESULTS: Eight studies were included in this review (five human studies, three animal model studies). Studies in humans suggest that pregnant women with substance use disorders are interested in engaging in physical activity interventions; however, known acute metabolic and physiological responses to prenatal exercise may be impaired in this population. Rodent models show preliminary evidence for improved mental health outcomes following prenatal exercise for substance use disorders. CONCLUSION: The findings from this review may inform the development of future clinical trials to test the effect of structured exercise programs as an adjunctive treatment option for pregnant women with substance use disorders.

Physical activity and gestational weight gain predict physiological and perceptual responses to exercise during pregnancy.

BACKGROUND: Exercise is known to improve the health of the pregnant woman and her child. Studies that have evaluated physiological parameters during prenatal exercise have conflicting results. Better understanding of these physiological responses can modify exercise prescriptions, safety, and monitoring strategies. We examined the association between age, prepregnancy body mass index (BMI), gestational weight gain (GWG), and physical activity (PA) levels, factors that may influence a change in physiological (HR, VO2 responses) and perceptual (RPE) responses to acute exercise throughout pregnancy. METHODS: Twenty-two healthy pregnant women (31.4 ± 3.7 years) performed a Submaximal incremental Walking Exercise Test (SWET). Early- (13-18 weeks), mid- (24-28 weeks), and late-pregnancy (34-37 weeks) were compared. VO2 (L/min; ml/kg/min), HR (bpm), and RPE were collected at the end of each test stage. PA was determined by accelerometry. We associated PA levels, GWG, prepregnancy BMI, and age with HR, RPE, and VO2 responses. RESULTS: HR, RPE, and absolute VO2 were higher in late-pregnancy compared to earlier time points (p < .05; η2 = 0.299-0.525). Regression models were built for HR (all time points), RPE (early- and late-pregnancy), and VO2 (L/min; late-pregnancy). HR (late-pregnancy) was predicted by time in vigorous PA, GWG, age, and prepregnancy BMI (r2 = 0.645; SEE = 5.84). RPE (late-pregnancy) was predicted by sedentary time, GWG, prepregnancy BMI, and age (r2 = 0.662; SEE = 1.21). CONCLUSION: Physiological/perceptual responses were higher in late-pregnancy compared to other time points and associated with combined PA, GWG, prepregnancy BMI, and age. These findings can be used to modify exercise prescriptions and designs for future PA interventions in pregnant women.

The Effect of Maternal Physical Activity and Gestational Weight Gain on Placental Efficiency.

INTRODUCTION: Adherence to physical activity (PA) and gestational weight gain (GWG) recommendations during pregnancy has been shown to improve maternal and fetal health outcomes, including reducing the risk for chronic diseases. Limited research has evaluated the effect of meeting PA in combination with GWG recommendations on placental efficiency (Pl-E), a surrogate marker of the placenta's ability to exchange nutrients and gas based on surface area. The purpose of this study was to measure and compare Pl-E based on meeting PA and GWG recommendations. METHOD: Healthy pregnant women (n = 61) wore accelerometers in their second and third trimesters to objectively measure PA. Women were classified as active or inactive at each time point based on meeting the 2019 Canadian prenatal PA guidelines. Total GWG was calculated as weight measured in the third trimester minus self-reported prepregnancy weight, and were categorized as insufficient (n = 19), adequate (n = 22), and excessive (n = 20) according to the 2009 Institute of Medicine guidelines. Placental weight (PW) and birth weight (BW) were measured within 30 min of delivery and 24-48 h postdelivery, respectively. Pl-E was determined in three ways: BW:PW ratio, residual BW, and measured BW, with a higher value indicating better Pl-E. Pl-E was compared by PA and GWG status using a two-way ANOVA. RESULTS: No differences were found in the BW:PW ratio or residual BW corresponding to PA and GWG status. Measured BW was significantly higher in newborns of women who gained weight excessively compared with those who gained insufficient weight (P < 0.05). CONCLUSION: These findings suggest that prenatal PA does not compromise Pl-E; however, further research is required to evaluate the potential mechanistic benefits of meeting PA and GWG guidelines on the placenta.

Cross-Validation of Ratings of Perceived Exertion Derived from Heart Rate Target Ranges Recommended for Pregnant Women.

Currently, there are no established evidence-based rating of perceived exertion (RPE) targets for physical activity (PA) in pregnant women. Yet, a set of target heart rate (HR) ranges have been recommended. Using the Borg Scale, we aimed to determine and validate the RPE target ranges for different PA intensities derived from the recommended HR ranges in the 2019 Canadian Guideline for PA throughout pregnancy. We assessed 13 pregnant women (age: 31.2 ± 3.5 years; gestational age: 20.5 ± 5.0 weeks) using the following three phases: 1) the incremental submaximal walking test to develop the linear regression equation; 2) establishment of the RPE targets for light- and moderate-intensity PA; 3) moderate-intensity exercise session aiming to cross-validate RPE targets in women whose HR ranges were within (Step 1; six participants; 36 RPE values) or outside (Step 2; seven participants; 42 RPE values) the guideline. Study Phase 1 showed a strong linear relationship between RPE x HR (RPE = -7.370 + 0.155*HR; R2 = 0.863). RPE targets for pregnant women aged ≤ 29 years are 8-12 (light-intensity) and 12-15 (moderate-intensity), respectively. For women aged ≥ 30 years, RPE targets are 8-11 (light-intensity) and 11-14 (moderate-intensity), respectively. The cross-validation suggested no differences between predicted (13.4 ± 0.7) vs. observed RPE (13.3 ± 1.4; p = 0.703) and a strong % agreement (Step 1 = 80.6%; Step 2 = 73.8%) between observed RPE and its predicted range. Thus, we have determined pregnancy-specific, evidence-based RPE targets. These RPE targets will help exercise professionals, other health care providers, and pregnant women to easily monitor exercise intensity during pregnancy to meet recommended Canadian PA Guideline.

Does "Sitting" Stand Alone? A Brief Report Evaluating the Effects of Prenatal Sedentary Time on Maternal and Newborn Anthropometric Outcomes.

BACKGROUND: Research on sedentary behavior and effects on maternal and newborn outcomes has been inconclusive. The objective of this report was to correlate sedentary time with maternal and fetal anthropometric measurements and compare the effect on sedentary time based on meeting prenatal activity guidelines. METHODS: Healthy pregnant women (N = 61) in their second trimester (24-28 wk gestation) provided 7-day accelerometry data. Outcomes, including neonatal weight, length, and body fat percentage, were collected 24 to 48 hours after delivery. Placenta weight was measured immediately after delivery. Gestational weight gain was calculated by subtracting self-reported prepregnancy weight from measured weight at 38 weeks gestation. Correlations between sedentary time and outcomes were tested with Spearman and Pearson coefficient of correlations in all women separately and in accordance with the 2019 Canadian prenatal exercise guidelines. RESULTS: No significant associations were found between sedentary time and the selected outcomes, even when compared by prenatal exercise level. There was no difference in total time spent sedentary between active (576.7 [52.8] min) and inactive women (599.3 [51.6] min). CONCLUSIONS: Meeting exercise recommendations during pregnancy does not significantly decrease total sedentary time. Future studies should aim to evaluate the health effects of both decreasing sedentary time and meeting prenatal exercise guidelines.

Physical Activity During Pregnancy Is Associated with Increased Placental FATP4 Protein Expression.

Placental function is of utmost importance to ensure proper fetal development in utero. Among the placenta's many roles includes the passage of sufficient macronutrients, such as glucose, amino acids, and fatty acids, to the fetus. Macronutrients are carried from maternal circulation to the fetus across transporters within the placenta. The objective of this study was to examine the impact of (i) an acute bout of exercise and (ii) chronic exercise participation on placenta nutrient transporter expression and localization. To investigate the effect of acute exercise, pre- and post-exercise serum was collected from pregnant (n = 5) and non-pregnant (n = 5) women who underwent a moderate-intensity exercise session and used to treat BeWo cells. To assess chronic physical activity, we analyzed term placenta from women categorized as active (n = 10) versus non-active (n = 10). Protein expression and localization for the transporters GLUT1, SNAT1, and FATP4 were examined for both groups. GLUT1 expression in BeWo cells treated with serum from pregnant women was higher compared with that from non-pregnant, independent of exercise. FATP4 protein expression was elevated in the term placenta of active women. Immunohistochemistry analysis of term placenta illustrated increased staining of FATP4 in placental tissue from active women and differential staining pattern of GLUT1 depending on physical activity status. Chronic exercise during pregnancy increases the expression of placental FATP4 in vivo, suggesting greater metabolism and usage of fatty acids. Additionally, serum from pregnant women could contain factors that increase GLUT1 protein expression in vitro. BeWo cells treated with pre- and post-exercise serum from pregnant women resulted in greater GLUT1 expression compared with those treated with pre- and post-exercise serum from non-pregnant women. Physical activity appears to differentially impact key placental transporters involved in the transfer and availability of nutrients from mother to fetus. Future research ought to examine the mechanisms involved in regulating these changes and their impact on fetal growth and health.

Determination of minimal recording period to assess resting heart rate variability during pregnancy.

Traditionally, resting heart rate variability (rHRV) is measured for 10 min using the last 5 min for analyses (e.g., criterion period). It is unknown whether the measurement period can be shortened in pregnant women as there are currently no established standards. We aimed to compare shorter time segments (e.g., from the 1st to 10th minutes) of the parasympathetic index natural logarithm transformation of root mean square of successive R-R differences (Ln rMSSD) with the criterion period in pregnant and nonpregnant women. Twelve pregnant (age: 30.8 ± 3.4 years; gestational age: 20.1 ± 5.0 weeks) and 15 nonpregnant women (age: 29.8 ± 4.0 years) were included. rHRV was measured using a portable heart rate monitor for 10 min while sitting. Ln rMSSD difference/agreement between shorter time segments and criterion period was analyzed. The result observed between the 4th-5th minutes was the shortest time segment not different from/highly agreed with the criterion period in pregnant women (difference [95% confidence interval (CI)]: -0.10 [-0.22 to 0.02]/bias ± 1.96 × SD: -0.06 [-0.38 to 0.25]). In nonpregnant women, the 2nd-3rd-minute segment was the shortest with similar results (difference [95% CI]: -0.04 [-0.15 to 0.07]/bias ± 1.96 × SD: -0.03 [-0.39 to 0.32]). The Ln rMSSD was found to be stable from the 5th-10th minutes and the 3rd-10th minutes in pregnant and nonpregnant women, respectively. A shortened rHRV assessment can increase its applicability in clinical/exercise-training settings. Novelty Ln rMSSD can be measured for 5 min in pregnant women, with the last 1-min segment analyzed. The last 1-min segment from 3 min can be used for rHRV measurement in nonpregnant women. The shortened rHRV assessment can facilitate its applicability in clinical/exercise-training settings.

Examination of the Myokine Response in Pregnant and Non-pregnant Women Following an Acute Bout of Moderate-Intensity Walking.

BACKGROUND: It is recommended that women accumulate 150-min of weekly moderate-intensity physical activity (MPA) when pregnant. Engaging in regular physical activity (PA) confers many health benefits to both the mother and the fetus. However, the molecular mechanisms by which these health benefits are bestowed are not well understood. One potential factor that may be contributing to the observed benefits is myokines, which are small peptides secreted by skeletal muscles. In the non-pregnant population, myokines are believed to be involved in the molecular mechanisms resulting from PA. The objective of this study was to characterize and compare the myokine profile of pregnant and non-pregnant women, after an acute bout of MPA. METHODS: Pregnant (n = 13) and non-pregnant (n = 17) women were recruited from the Ottawa region to undergo a treadmill walking session at moderate-intensity (40-60% heart rate reserve). Pre- and post-exercise serum samples were taken, and a set of 15 myokines were analyzed although only 10 were detected. IL-6 was analyzed using a high-sensitivity assay, while FGF21, EPO, BDNF, Fractalkine, IL-15, SPARC, FABP-3, FSTL-1, and oncostatin were analyzed using various multiplex assays. RESULTS: The pregnant and non-pregnant groups did not differ in terms of age, height, non/pre-pregnancy weight, BMI, and resting heart rate. Baseline levels of EPO and oncostatin were higher in the pregnant group while FGF21 was higher in the non-pregnant group. Circulating levels of three myokines, FGF21, EPO, and IL-15 significantly increased in response to the acute exercise in the pregnant group. Non-pregnant women exhibited an increase in three myokines, FABP-3, FSTL-1, and oncostatin, while one myokine, EPO, decreased post-exercise. SPARC, fractalkine and BDNF were shown to increase post-exercise regardless of pregnancy status while the response for BDNF was more pronounced in the non-pregnant group. CONCLUSION: This is the first study examining myokine response following an acute bout of PA in pregnancy. Moderate intensity PA, which is recommended during pregnancy, elicited an increase in four myokines post-compared to pre-exercise in the pregnant group. Further research is warranted to understand the role of myokines in pregnancy.

Antibiotic exposure and risk of weight gain and obesity: protocol for a systematic review.

BACKGROUND: The prevalence of obesity is increasing worldwide, and there is growing interest in better delineating the role of the human gut microbiome in this phenomenon. Obesity-specific gut microbiome features have been observed in both human and animal studies, and these variations appear to play a causative role in increasing body weight. There is evidence that antibiotics can modify the composition and diversity of the gut microbiome and that this may contribute to body weight changes. The primary objective of the proposed systematic review is to evaluate and synthesize the existing evidence evaluating the possible association between antibiotic use, weight gain, and obesity. METHODS: A comprehensive search of the MEDLINE and EMBASE databases will be performed. Both randomized and non-randomized studies (excluding case reports) in neonates, children, adults, and pregnant women will be included. The exposure of interest is antibiotics of any type, duration, and route given for any indication. All included studies must have a comparator group. The primary outcomes are the development of overweight and obesity. Secondary outcomes are percent weight-change from baseline and change in body mass index or waist circumference. Additional secondary outcomes in pregnant women are gestational weight gain, postpartum weight retention, offspring birth weight, childhood weight, and obesity. Risk of bias of included trials will be performed. Two reviewers will screen and perform data extraction independently. DISCUSSION: This systematic review will summarize the existing evidence evaluating the association between antibiotic use, weight gain, and obesity and facilitate the identification of important gaps and uncertainties in the literature. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42017069177.

The Transcription Factor NFIL3 Is Essential for Normal Placental and Embryonic Development but Not for Uterine Natural Killer (UNK) Cell Differentiation in Mice.

Mice ablated for the gene encoding the transcription factor Nfil3 lack peripheral natural killer (NK) cells but retain tissue-resident NK cells, particularly in mucosal sites, including virgin uterus. We undertook a time course histological study of implantation sites from syngeneically (Nfil3(-/-)) and allogeneically (BALB/c) mated Nfil3(-/-) females. We also examined implantation sites from Rag2(-/-)Il2rg(-/-) females preconditioned by adoptive transfer of Nfil3(-/-) marrow or uterine cell suspensions to identify the Nfil3(-/-) pregnancy aberrations that could be attributed to nonlymphoid cells. Uterine NKs (UNKs) reactive and nonreactive with the lectin Dolichos biflorus agglutinin (DBA) differentiate, localize, and mature within Nfil3(-/-) implantation sites, although at reduced abundance. The DBA nonreactive UNK cells were enriched following Nfil3(-/-) marrow transplantation. Uterine lumen closure, early embryonic development, and differentiation of antimesometrial decidua were delayed in Nfil3(-/-) implantation sites. Major disturbances to the decidual-trophoblast interface that did not lead to fetal death were attributed to NFIL3 deficiency in trophoblast. At midgestation, vessels of the placental labyrinth were enlarged, suggestive of reduced branching morphogenesis. A major term complication in most Nfil3(-/-) × Nfil3(-/-) pregnancies but not Nfil3(-/-) × Nfil3(+/-) pregnancies was dystocia. These studies highlight the differentiation potential and functions of Nfil3(-/-) UNK cell progenitors and illustrate that much of the implantation site histopathology associated with this strain is due to Nfil3 deletion in nonlymphoid cell lineages.