Neonatal Size Research Articles

Neonatal cuff sizes cause error in non-invasive blood pressure measured in cats

Neonatal cuff sizes cause error in non-invasive blood pressure measured in cats

Continuous Subcutaneous Infusion Versus Multiple Daily Injections of Insulin for Pregestational Diabetes in Pregnancy: A Systematic Review and Meta-Analysis.

The use of continuous subcutaneous insulin infusion (CSII) therapy in pregnancies affected by pregestational diabetes mellitus (DM) has generated mixed outcome data worthy of further investigation. This systematic review and meta-analysis aims to evaluate clinical outcomes associated with CSII versus multiple daily injections (MDIs) in pregnant persons with pregestational DM. A predefined, systematic, librarian-assisted search of MEDLINE (PubMed), Embase, Cochrane Library, Scopus, ClinicalTrials.gov, and World Health Organization International Clinical Trial Registry Platform (published from 2010 to 2022) yielded 3003 studies describing pregnancy outcomes associated with CSII and/or MDI for pregestational DM. The primary exposure was mode of insulin administration, with cesarean delivery and neonatal hypoglycemia as the primary maternal and neonatal outcomes, respectively. Secondary outcomes included hypertensive disorders of pregnancy, first and third-trimester glycemic control, large-for-gestational age (LGA) neonate, preterm birth, neonatal intensive care unit admission, need for respiratory support, hyperbilirubinemia, 5-minute Apgar <7, shoulder dystocia, and perinatal mortality. We calculated pooled odds ratios (OR) with 95% confidence intervals (CI) using random-effects models. Among 39 eligible studies, 39% of the 5518 pregnancies included were exposed to CSII. Odds of cesarean delivery were higher with CSII (20 studies: 63% vs 56%, odds ratio [OR] 1.3 [95% confidence interval (CI) 1.2-1.5]), but we did not identify a difference in the odds of neonatal hypoglycemia (23 studies: 31% vs 34%, OR 1.1 [95% CI 0.9-1.5]). Among secondary outcomes, only the odds of LGA (20 studies: 47% vs 38%, OR 1.4 [95% CI 1.2-1.6]) were higher in individuals using CSII versus MDI. Use of CSII (vs MDI) for pregestational DM in pregnancy is associated with higher odds of cesarean delivery and delivery of an LGA neonate. Further evaluation of how CSII use may influence neonatal size and delivery route is warranted.

Birth Size of Neonates and Its Association with Seasonality

The aim of the study is to evaluate the relationship between the season of birth and the birth weight and length of Bulgarian newborns. The weight and length data of 6517 (6098 full-term and 419 preterm) live births in 2000–2001 were collected from the birth registry of II Hospital of Obstetrics and Gynaecology “Sheynovo”, Sofia, Bulgaria. Statistical analyses were done using the SPSS 16 software for Windows: descriptive statistics; the t-test (p&lt;0.05); One-Way ANOVA, (Tukey, HSD-test, p&lt;0.05) and the Pearson’s correlation. The sunshine dura-tion data for 2000 and 2001 were collected at the Sofia Meteorological Station. The mean weight of Bulgarian neonates born in 2000-2001 was 3389.8 g in boys and 3261.8 g in girls. The average newborn’s length was 51.0 cm and 50.3 cm in boys and girls, respectively. In all seasons, significant gender differences were observed with a priority for boys (p≤0.001). The winter period was identified with a peak in birth length for both sexes, and spring and summer were the seasons with the lowest values for boys and girls, respectively. A significant positive correlation between birth length and the daily amount of sunshine during the prenatal period was found (p&lt;0.001). Seasonal fluctuations influenced weight and length in Bulgarian neonates. The results obtained in this study can be useful in prenatal diagnostics, neonatal care, and health prevention of pregnant women and neonates.

Scaling of Gait, Limb Posture, Forces, and Inertial Properties in Terrestrial Locomotion of American Alligators Across a Thousand-Fold Increase in Body Mass

Synopsis Scaling of body shape, gait, limb kinematics, and kinetics can inform about mechanical and energetic constraints influencing animal locomotion on land. However, our knowledge of terrestrial locomotion among tetrapods is biased toward animals that use parasagittal limb postures (mammals and birds). Whether species that use non-parasagittal limb postures (e.g., crocodylians and lizards) share similar scaling principles remains uncertain, especially toward the larger end of the body size spectrum. Here, we compare new data from large adult American alligators (140–223 kg) with previous data from smaller individuals (0.2–5.6 kg) to evaluate the scaling of gait, limb posture, ground reaction forces, and inertial properties of body segments over a size range spanning three orders of magnitude. Larger alligators walked with higher relative stride frequencies and shorter relative stride lengths at equal dimensionless speeds, suggesting that alligators prioritize stance phase mechanical work reduction at the expense of higher costs for swing as they increase in size. Limb posture also changed with body mass: ∼1 kg and larger alligators typically used more adducted and extended limbs, which is expected to mitigate limb muscle forces during stance. Ground reaction forces were increasingly hindlimb dominant as alligators grow to larger size, paralleled by a posterior shift in the center of mass. Counterintuitively, the forelimb grew faster in mass than the hindlimb, possibly because recruited muscle volume is closer to its maximum capacity in the forelimb, compelling larger alligators to keep up with increased mechanical demands via muscle growth more for the forelimb than the hindlimb. These results highlight the numerous changes in body proportions and locomotor performance that are required among animals that use non-parasagittal limb posture, as they grow from neonatal sizes into large adults.

Combined Toxicity of Glyphosate (Faena®) and Copper to the American Cladoceran Daphnia exilis—A Two-Generation Analysis

Glyphosate and copper are common pollutants in water and soil. Glyphosate is the most used herbicide worldwide; despite being claimed to be a low-toxicity pesticide and easily degraded, several studies have demonstrated glyphosate’s occurrence and toxicity in freshwater ecosystems. Copper is an essential micronutrient; however, at high concentrations, it becomes toxic, and it is a persistent contaminant discharged from agricultural and industrial activities. Both glyphosate and Cu are agrochemicals that can occur in aquatic environments and produce stress in aquatic biota. Cladocerans are important zooplankters, and their sensitivity to chemical stressors has been widely documented. In this study, the North American cladoceran Daphnia exilis was exposed to glyphosate (Faena®) and Cu mixtures. The effects were assessed in two generations to determine toxicity impairment in the parental (P1) and filial (F1) generations. The 48 h median lethal concentration (LC50) of both chemicals was determined. After this, the generations P1 and F1 were exposed for 21 days to three concentrations of glyphosate and Cu mixtures (1.04 mg L−1 + 2.45 μg L−1, 1.24 mg L−1 + 3.09 μg L−1, and 1.57 mg L−1 + 4.31 μg L−1), starting from neonates. Survival and reproduction were recorded, and macromolecule content and the size of neonates were measured in the progeny. The LC50 was 4.22 mg L−1 for Faena® and 13.45 μg L−1 for copper. Exposure to glyphosate and copper reduced fecundity and the number of clutches per female, delayed age at first reproduction, and increased the number of aborted eggs; these effects were more evident in the F1 than in the P1. In both generations, the concentration of carbohydrates and lipids was significantly reduced. The treatment and the brood number influenced the total length of neonates, but the total length did not differ significantly, whereas body length and body width decreased in F1. Glyphosate and copper mixtures significantly increased toxicity in D. exilis in the F1 generation, probably because the parents produced impaired progenies. Results warn about transgenerational effects in planktonic species chronically exposed to pollutants.

Immune Modulation of HIV-1 Reservoir Size in Early-Treated Neonates.

Immune mechanisms that modulate human immunodeficiency virus-1 (HIV-1) reservoir size in neonates are poorly understood. Using samples from neonates who initiated antiretroviral therapy shortly after birth, we demonstrate that interleukin-8-secreting CD4 T cells, which are selectively expanded in early infancy, are more resistant to HIV-1 infection and inversely correlated with the frequency of intact proviruses at birth. Moreover, newborns with HIV-1 infection displayed a distinct B-cell profile at birth, with reduction of memory B cells and expansion of plasmablasts and transitional B cells; however, B-cell immune perturbations were unrelated to HIV-1 reservoir size and normalized after initiation of antiretroviral therapy. Clinical Trials Registration. NCT02369406.

Percutaneous epicardial pacing in infants using direct visualization: A feasibility animal study.

Pacemaker implantation in infants and small children is limited to epicardial lead placement via open chest surgery. We propose a minimally invasive solution using a novel percutaneous access kit. To evaluate the acute safety and feasibility of a novel percutaneous pericardial access tool kit to implant pacemaker leads on the epicardium under direct visualization. A custom sheath with optical fiber lining the inside wall was built to provide intrathoracic illumination. A Veress needle inside the illumination sheath was inserted through a skin nick just to the left of the xiphoid process and angled toward the thorax. A needle containing a fiberscope within the lumen was inserted through the sheath and used to access the pericardium under direct visualization. A custom dilator and peel-away sheath with pre-tunneled fiberscope was passed over a guidewire into the pericardial space via modified Seldinger technique. A side-biting multipolar pacemaker lead was inserted through the sheath and affixed against the epicardium. Six piglets (weight 3.7-4.0 kg) had successful lead implantation. The pericardial space could be visualized and entered in all animals. Median time from skin nick to sheath access of the pericardium was 9.5 (interquartile range [IQR] 8-11) min. Median total procedure time was 16 (IQR 14-19) min. Median R wave sensing was 5.4 (IQR 4.0-7.3) mV. Median capture threshold was 2.1 (IQR 1.7-2.4) V at 0.4 ms and 1.3 (IQR 1.2-2.0) V at 1.0 ms. There were no complications. Percutaneous epicardial lead implantation under direct visualization was successful in six piglets of neonatal size and weight with clinically acceptable acute pacing parameters.

Effects of Exposure to Cadmium, Microplastics, and Their Mixture on Survival, Growth, Feeding, and Life History of Daphnia magna.

There is concern that microplastics can act as a vector for cadmium (Cd), altering the bioavailability and subsequent toxicity of Cd to ecologically important species such as Daphnia magna. The toxicity of Cd to D. magna has been well described; however, what is not known, and what the present study addresses, was how the addition of polyethylene microplastic altered Cd toxicity. Using high-throughput feeding assays and size assessments, the present study quantified effects of exposure to Cd, microplastic, or their mixture on daphnids from neonate to adult. Exposure to Cd inhibited feeding efficiency, while exposure to microplastic inhibited growth rates of juveniles. Daphnia magna coexposed to Cd and microplastic showed significant decreases in both feeding and prereproductive growth rate. There were no differences in life-history traits across any treatments. The alterations of feeding and growth while maintaining reproductive endpoints (time to first brood, reproductive frequency, the number of neonates released at each reproductive event, and the size of neonates produced) might be the result of a shift in energy allocation away from somatic growth, allowing individuals to maintain reproductive output despite lower nutritional reserves. Our findings suggest that cocontamination of microplastic and Cd has additive effects on feeding and growth rates, resulting in a greater energy allocation shift. Environ Toxicol Chem 2023;42:1401-1408. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Composition of the maternal gastrointestinal microbiome as a predictor of neonatal birth weight.

The biological mechanism by which the maternal gastrointestinal microbiota contributes to fetal growth and neonatal birth weight is currently unknown. The purpose of this study was to explore how the composition of the maternal microbiome in varying pre-gravid body mass index (BMI) groups are associated with neonatal birth weight adjusted for gestational age. Retrospective, cross-sectional metagenomic analysis of bio-banked fecal swab biospecimens (n = 102) self-collected by participants in the late second trimester of pregnancy. Through high-dimensional regression analysis using principal components (PC) of the microbiome, we found that the best performing multivariate model explained 22.9% of the variation in neonatal weight adjusted for gestational age. Pre-gravid BMI (p = 0.05), PC3 (p = 0.03), and the interaction of the maternal microbiome with maternal blood glucose on the glucose challenge test (p = 0.01) were significant predictors of neonatal birth weight after adjusting for potential confounders including maternal antibiotic use during gestation and total gestational weight gain. Our results indicate a significant association between the maternal gastrointestinal microbiome in the late second trimester and neonatal birth weight adjusted for gestational age. Moderated by blood glucose at the time of the universal glucose screening, the gastrointestinal microbiome may have a role in the regulation of fetal growth. Maternal blood glucose in the late second trimester significantly moderates the relationship between the maternal gastrointestinal microbiome and neonatal size adjusted for gestational age. Our findings provide preliminary evidence for fetal programming of neonatal birth weight through the maternal gastrointestinal microbiome during pregnancy.

Adrenal congestion in perinatal hypoxia: Sonographic assessment and relationship with hypoxic ischemic encephalopathy

BackgroundDuring hypoxia, blood flow to the brain, myocardium, and adrenal glands is preserved or even increased to maintain homeostasis. Adrenal congestion occurs when venous return remains insufficient. Several different ultrasound measurements of adrenal glands in neonates have been reported in the literature. However, there is no data related on adrenal gland size in neonates with perinatal hypoxia. AimsTo evaluate the adrenal congestion using by ultrasound (US) measurements in perinatal hypoxia, and to reveal the relationship of adrenal congestion with hypoxic-ischemic encephalopathy (HIE) grades and magnetic resonance imaging (MRI) findings. Study designProspective cohort study. SubjectsInfants with perinatal hypoxia who met therapeutic hypothermia criteria and were being cooled were included in the present study. The control group was established from healthy neonates admitted to our center during the recruitment. Outcome measuresThe gland area was measured by tracing, and both the corpus and crura widths were measured. ResultsWe reported adrenal gland area data of 110 newborns with HIE and compared them with 56 normal neonates. The adrenal size was significantly higher in the HIE group than in the control group (p<0,01). The frequency of adrenal congestion was 72.7% based on the selected cut-off values. The adrenal gland measurements were increased in the patients with perinatal hypoxia than those of the controls. ConclusionsIn the systemic evaluation of newborns with perinatal hypoxia, additional care should be taken regarding adrenal congestion. The measurement of adrenal size with 2D US will help us to diagnose or confirm adrenal congestion and possible hemorrhagic changes. The morphological data and cut-off values given in our study will be useful for neonatologists and pediatric radiologists to evaluate the patient while managing perinatal hypoxia.

Perinatal Outcomes and Neurodevelopment 1 Year after Birth in Discordant Twins According to Chorionicity.

Background and Objectives: This study aimed to compare maternal complications, perinatal outcomes, and neurodevelopment 1 year after the birth between concordant and discordant twins in monochorionic and dichorionic twins. Materials and Methods: This retrospective study included twin pregnancies delivered between 24 + 1 and 38 + 2 weeks of gestation between January 2011 and September 2019. Chorionicity was confirmed by ultrasonography and was categorized into monochorionic and dichorionic. Each was then divided into two groups (concordant and discordant) according to birth weight discordancy. Maternal complications and neonatal outcomes, including neurodevelopmental delays, were compared between the two groups. Results: A total of 298 pairs of twin pregnancies were enrolled, of which 58 (19.26%) women were pregnant with monochorionic diamniotic twins and 240 (80.54%) with dichorionic diamniotic twins. In both monochorionic and dichorionic twins, the discordant twins had a greater incidence of emergency deliveries because of iatrogenic causes than the concordant twins. Among dichorionic twins, discordant twins had lower birth weight rates and higher hospitalization rates and morbidities than concordant twins. Among monochorionic twins, discordant twins had a lower birth weight and higher neonatal mortality than concordant twins. The neonatal size was not a predictor of neurodevelopment in this group. Based on the logistic regression analysis, male sex, respiratory distress syndrome, and bronchopulmonary dysplasia were risk factors for the neurodevelopmental delay; birth weight discordancy was significant only in dichorionic twins. Conclusions: Perinatal outcomes in discordant twins may be poor, and neurodevelopment 1 year after birth was worse in discordant twins than in concordant twins. Discordancy in twins can be a risk factor for neurodevelopmental delay.

Transgenerational effects of benzotriazole on the gene expression, growth, and reproduction of Daphnia magna

Due to its widespread and intensive use as a corrosion inhibitor, benzotriazole is ubiquitously detected from a few parts per billion to several hundred parts per million in aquatic environments. The long-term toxicity of benzotriazole is unclear despite its low acute toxicity. Therefore, we investigated the transgenerational effects of benzotriazole at the genomic and individual levels using the freshwater zooplankton Daphnia magna. Maternal exposure to sublethal concentrations (15 and 30 mg/L) of benzotriazole exerted transgenerational effects on D. magna at the genomic and individual levels even in descendants that have never been exposed to benzotriazole. Significant alterations in the expression of Cyp, GST, Vtg1, and Hb and in neonate size were observed in the unexposed F3 generation, confirming the transgenerational effect of benzotriazole. Interestingly, detoxification related genes Cyp and GST were unaffected or downregulated in the exposed generation but upregulated in the following unexposed generations. Furthermore, continuous multigenerational exposure to an environmental concentration (4.3 μg/L) of benzotriazole also upregulated detoxification genes in decent generations but exerted no individual-level effects in subsequent generations.

Association between maternal factors and fetal macrosomia in full-term singleton births.

Macrosomia, defined as a birth weight of ≥4000 g, is associated with a high risk of birth injury. Fetal growth is highly correlated with maternal conditions, and several maternal factors are associated with neonatal birth size. The current study aimed to assess maternal factors related to fetal macrosomia in a Taiwanese population. The medical records of pregnant mothers and their newborns were retrospectively reviewed. All singleton pregnancies delivered at and after 37 weeks of gestation were included in the analysis. Maternal and neonatal conditions were evaluated according to different birth weights. A total of 4262 infants were enrolled in our study. The mean birth weight was 3156 ± 383 g, including 77 (1.8%) cases with birth weight ≥4000 g, and 154 (3.6%) infants with birth weight <2500 g. The mean maternal body weight before delivery was 67.6 ± 10.0 kg. The mean 6-month gestational weight gain (6mGWG) was 12.3 ± 4.2 kg, and the mean maternal body mass index (BMI) was 26.2 ± 3.6 kg/m 2 . The maternal weight, height, and 6mGWG, gestational age, and placental weight were significantly positively correlated with neonatal birth weight. The odds ratios of macrosomia were 3.1 in neonates born to mothers with a 6mGWG of ≥15 kg, 6.3 in those born to mothers with gestational diabetes mellitus, and 4.1 in those born to mothers with a BMI of ≥30 kg/m 2 . Newborn macrosomia was associated with adverse events in pregnant mothers and newborn infants. Gestational diabetes mellitus, 6mGWG, and maternal BMI are significantly correlated with neonatal macrosomia in full-term singleton births. Further, neonatal macrosomia is an important cause of maternal and neonatal morbidity. Hence, pregnant women should undergo maternal counseling for weight management before and during pregnancy, and the appropriate delivery method should be identified to prevent perinatal adverse events.

Quantifying changes in umbilicus size to estimate the relative age of neonatal blacktip reef sharks (Carcharhinus melanopterus).

Sharks can incur a range of external injuries throughout their lives that originate from various sources, but some of the most notable wounds in viviparous shark neonates are at the umbilicus. Umbilical wounds typically heal within 1 to 2 months post-parturition, depending on the species, and are therefore often used as an indicator of neonatal life stage or as a relative measure of age [e.g. grouping by umbilical wound classes (UWCs), according to the size of their umbilicus]. To improve comparisons of early-life characteristics between studies, species and across populations, studies using UWCs should integrate quantitative changes. To overcome this issue, we set out to quantify changes in umbilicus size of neonatal blacktip reef sharks (Carcharhinus melanopterus) around the island of Moorea, French Polynesia, based on temporal regression relationships of umbilicus size. Here, we provide a detailed description for the construction of similar quantitative umbilical wound classifications, and we subsequently validate the accuracy of our classification and discuss two examples to illustrate its efficacy, depletion rate of maternally provided energy reserves and estimation of parturition period. A significant decrease in body condition in neonatal sharks as early as twelve days post-parturition suggests a rapid depletion of in utero-allocated energy reserves stored in the liver. Back calculations of timing of birth based on the umbilicus size of neonates determine a parturition season from September to January, with most parturitions occurring during October and November. As such, this study contributes valuable data to inform the conservation and management of young-of-the-year blacktip reef sharks, and we therefore encourage the construction and use of similar regression relationships for other viviparous shark species.

Factors Associated with Mortality of Neonates Admitted to a Tertiary Care Neonatal Unit

Background: The neonatal period is the most susceptible phase of life. In the aim of this study was to assess the causes and factors associated with neonatal mortality. Methodology: This study was a Retrospective study of medical records for 2 years (Jan. 2020- Dec. 2021). The age, sex, gestational age, and morbidity and mortality profile of all SNCU admissions in 1 year were determined, and the difference between inborn (those born in Hospital) and out born (neonates delivered outside and referred) was calculated. Results: Of the 1600 neonates admitted, 61.5% neonates were males, 57.4% were Inborn and 42.8% were outborn. Approximately, 33.4% were preterm, and renal cardiovascular (20.4%), Neurological disorder (18.6%), and Respiratory related infection (19.1%) were the chief morbidities. The chief causes of mortality were low birth weight with AOR 1.29 (0.836-2.0120), respiratory support that includes O2 with AOR 5.817 (3.367-10.051), CPAP with AOR 4.902 (2.745-8.754), CMV with AOR 4.251(2.184-8.274) and Level of Care with AOR 4.85 (3.102-11.471). This factor was statistically associated with neonatal mortality. Conclusion: Low birth weight, respiratory support, neonate size, and degree of care were all found to be associated with newborn mortality in this study. As a result, hospitals ought to emphasize enhancing antenatal, intrapartum, and standardized care for newly admitted infants. A prospective study is what we suggest.

Interactions between maternal health and placental morphology on neonate body composition

BackgroundWe aimed to examine maternal metabolic correlates of neonate body composition, and the potential mediating effect of the placenta. MethodsData were collected throughout pregnancy and at delivery. An oral glucose tolerance test (OGTT) was conducted in order to diagnose or rule out gestational diabetes mellitus (GDM). Maternal weight and blood pressure were taken and hypertension and gestational weight gain (GWG) were defined. Gestational age, birth weight (BW) and weight to length ration (WLR) were recorded. Photographs were taken of the placenta, and the widths and lengths were measured digitally. Body composition was analysed via air displacement plethysmography or dual-energy x-ray absorptiometry. Mediation models were conducted to determine the mediation effect of the placental variables on the relationships between maternal health variables and neonate outcomes. Next, interaction terms were added to models to determine how maternal and placental variables interacted in their effect on neonate outcomes. ResultsA total of n = 280 women were included in the analysis. Majority were overweight or obese. Fourteen percent of women developed GDM during pregnancy, 5% had hypertension during pregnancy, 32% were HIV positive, and 32% had anemia. For the birth weight outcome, coefficients of BMI were attenuated by the addition of placental variables (Model 1 ß=18.66 vs Model 2 ß=16.40). Similar patterns were evident for GWG and hypertension, and for the WLR outcome. In all cases the addition of the placental variables attenuated associations between maternal exposures and neonatal outcomes, yet the level of significance did not change. Inclusion of interaction terms reversed the direction of the relationships between hypertension and BW and WLR, and between GWG and WLR. ConclusionThe placenta buffers some harmful effects of obesity, GWG, and hypertension on neonate size, and placental efficiency interacted with most maternal risk factors to either counteract, or attenuate relationships with neonate size at birth. However the placenta was unable to completely counteract the negative effect of excess nutrient supply on in utero growth.

Using non-parametric Bayes shrinkage to assess relationships between multiple environmental and social stressors and neonatal size and body composition in the Healthy Start cohort

BackgroundBoth environmental and social factors have been linked to birth weight and adiposity at birth, but few studies consider the effects of exposure mixtures. Our objective was to identify which components of a mixture of neighborhood-level environmental and social exposures were driving associations with birth weight and adiposity at birth in the Healthy Start cohort.MethodsExposures were assessed at the census tract level and included air pollution, built environment characteristics, and socioeconomic status. Prenatal exposures were assigned based on address at enrollment. Birth weight was measured at delivery and adiposity was measured using air displacement plethysmography within three days. We used non-parametric Bayes shrinkage (NPB) to identify exposures that were associated with our outcomes of interest. NPB models were compared to single-predictor linear regression. We also included generalized additive models (GAM) to assess nonlinear relationships. All regression models were adjusted for individual-level covariates, including maternal age, pre-pregnancy BMI, and smoking.ResultsResults from NPB models showed most exposures were negatively associated with birth weight, though credible intervals were wide and generally contained zero. However, the NPB model identified an interaction between ozone and temperature on birth weight, and the GAM suggested potential non-linear relationships. For associations between ozone or temperature with birth weight, we observed effect modification by maternal race/ethnicity, where effects were stronger for mothers who identified as a race or ethnicity other than non-Hispanic White. No associations with adiposity at birth were observed.ConclusionsNPB identified prenatal exposures to ozone and temperature as predictors of birth weight, and mothers who identify as a race or ethnicity other than non-Hispanic White might be disproportionately impacted. However, NPB models may have limited applicability when non-linear effects are present. Future work should consider a two-stage approach where NPB is used to reduce dimensionality and alternative approaches examine non-linear effects.

Ecotoxicity of nanosilver on cladocerans and the role of algae provision.

Silver nanoparticles (AgNPs) are applied in diverse industries due to their biocide and physicochemical properties; therefore, they can be released into aquatic systems, interact with environmental factors, and ultimately exert adverse effects on the biota. We analyzed AgNPs effects on Ceriodaphnia reticulata (Cladocera) through mortality and life-history traits, considering the influence of food (Tetradesmus obliquus, Chlorophyceae) presence and concentration. C. reticulata was exposed to AgNPs in acute (absence and two algae concentrations plus five AgNPs treatments) and chronic assays (two algae concentrations plus three AgNPs treatments). AgNPs did not affect algae flocculation but increased Ag+ release, being these ions less toxic than AgNPs (as proved by the exposure to AgNO3). A reduction in AgNPs acute toxicity was observed when algae concentration increased. Acute AgNP exposure decreased C. reticulata body size and heart rate. The chronic AgNP exposure reduced C. reticulata molt number, growth, heart rate, and neonate size:number ratio, being these effects mitigated at the highest algae concentration. Increases in relative size and number of neonates were observed in AgNP treatments suggesting energy trade off. The increased Ag+ release with food presence suggests that the AgNP-algae interaction might be responsible of the decreased toxicity. Although algae reduced AgNP toxicity, they still exerted adverse effects on C. reticulata below predicted environmental concentrations. Since algae presence reduces AgNP effects but increases Ag+ release, studies should be continued to provide evidence on their toxicity to other organisms.

The origin of placental mammal life histories.

After the end-Cretaceous extinction, placental mammals quickly diversified1, occupied key ecological niches2,3 and increased in size4,5, but this last was not true of other therians6. The uniquely extended gestation of placental young7 may have factored into their success and size increase8, but reproduction style in early placentals remains unknown. Here we present the earliest record of a placental life history using palaeohistology and geochemistry, in a 62 million-year-old pantodont, the clade including the first mammals to achieve truly large body sizes. We extend the application of dental trace element mapping9,10 by 60 million years, identifying chemical markers of birth and weaning, and calibrate these to a daily record of growth in the dentition. A long gestation (approximately 7 months), rapid dental development and short suckling interval (approximately 30-75 days) show that Pantolambda bathmodon was highly precocial, unlike non-placental mammals and known Mesozoic precursors. These results demonstrate that P. bathmodon reproduced like a placental and lived at a fast pace for its body size. Assuming that P. bathmodon reflects close placental relatives, our findings suggest that the ability to produce well-developed, precocial young was established early in placental evolution, and that larger neonate sizes were a possible mechanism for rapid size increase in early placentals.

Endocrine-disrupting potential and toxicological effect of para-phenylphenol on Daphnia magna

Several phenol derivatives are suspected endocrine disruptors and have received attention in risk assessment studies for several decades owing to the structural similarity between estrogens and phenolic compounds. We assessed the endocrine disrupting effect of the phenolic compound para-phenylphenol (PPP) through acute tests and evaluating chronic endpoints in an invertebrate model, Daphnia magna. Exposure of D. magna to PPP induced substantial adverse effects, namely, reduced fecundity, slowed growth rate, delayed first brood, and a reduction in neonate size. Furthermore, we investigated the mRNA expression of relevant genes to elucidate the mechanism of endocrine disruption by PPP. Exposure of D. magna to PPP induced the substantial downregulation of genes and markers related to reproduction and development, such as EcR-A, EcR-B, Jhe, and Vtg. Consequently, we demonstrated that PPP has an endocrine disrupting effect on reproduction and development in D. magna.