Mortality and adverse neurologic outcomes are greater in preterm male infants

Sex-differences in Mothers' own milk and neurodevelopmental outcomes in preterm infants

Objective

To identify sex-specific feeding patterns and associations with growth and neurodevelopment in preterm infants during NICU through 2 years of corrected age (CA).

Methods

A cohort study was conducted with 216 preterm infants (gestational age 28 0/7 to 32 0/7 weeks). Daily feeding regimens, including mother's own milk (MOM), human donor milk, and formula; daily growth; acute and chronic pain/stress were documented during NICU. NICU Network Neurobehavioral Scale (NNNS) (36 to 38 postmenstrual age), and Bayley Scales of Infant and Toddler Development (Bayley) Edition III (1 and 2 years of CA) were measured.

Results

Between week 9 to 16 after birth, only females showed a positive association between growth z-score and proportion of MOM intake before week 8 (p < 0.05). Sex-differentiated associations between MOM and stress were observed (p < 0.05). MOM proportion was positively correlated with language or cognitive scores at 2 years of CA in females (p = 0.01), this correlation not evident in males.

Conclusions

We discovered a sex-specific "window of opportunity" for feeding, growth and risk predictors for neurodevelopment up to 2 years of CA. These insights may inform development of tailored feeding regimens, potentially mitigating growth and development differences observed between males and females.

Gender differences in survival rates among extreme low birth weight infants: Insight from a 16-year, single-centre study

BackgroundPreterm infants with a birth weight of less than 1000 grams (g), extreme low birth weight (ELBW) account for approximately 0.6% of all live births. Despite their small proportion, they contribute significantly to neonatal deaths, short-term morbidities, and long-term sequalae among survivors. This study aims to evaluate the survival trends of ELBW infants over the study period and the impact of gender on survival odds.MethodsThis retrospective cohort study involved ELBW infants admitted to our neonatal intensive care unit over 16 years (2008-2023). We examined their survival trends in context with their gender to analyze impact on survival odds.ResultsOut of 336 infants who met the inclusion criteria, 175 were males (52.1%) and 161 (47.9%) were females. The mean birth weight for males was 780 g (SD = 134 g), and 770 g (SD = 132) for females, while the mean gestational age (GA) was 26.2 weeks (SD = 2.14 week) for males and 26.6 weeks (SD = 2.18 week) for females. Female ELBW infants had a higher survival rate of 78.9% compared to 68.6% for males, with an odds ratio (OR) of 1.712 (p value = 0.017). The survival advantage for females was more evident among birth weight of less than (<) 750 g (62% vs 44%) with an OR of 2.06 (p value = 0.023).ConclusionThis study demonstrated that female ELBW infants have a higher survival rate than males, particularly with birth weight under 750 g.

Preterm Sex Differences in Neurodevelopment and Brain Development from Early Life to 8 Years of Age

OBJECTIVE

To examine sex differences in neurodevelopmental outcomes and brain development from early life to 8 years in males and females born preterm.

STUDY DESIGN

This was a prospective cohort study of infants born very preterm (24-32 weeks of gestation) and followed to 8 years with standardized measures of neurodevelopment. Brain magnetic resonance imaging scans were performed soon after birth, term-equivalent age, and 8 years. The relationship between sex, severe brain injury, early pain exposure, fractional anisotropy, and neurodevelopmental outcomes were assessed using multivariable generalized estimating equations.

RESULTS

Males (n = 78) and females (n = 66) were similar in clinical risk factors. Male sex was associated with lower cognitive scores (β = -3.8, P = .02) and greater motor impairment (OR, 1.8; P = .04) across time. Male sex was associated with lower superior white matter fractional anisotropy across time (β = -0.01; P = .04). Sex moderated the association between severe brain injury, early pain, and neurodevelopmental outcomes. With severe brain injury, males had lower cognitive scores at 3 years of age (P < .001). With increasing pain, females had lower cognitive scores at 8 years of age (P = .008), and males had greater motor impairment at 4.5 years of age (P = .001) and 8 years of age (P = .05).

CONCLUSIONS

Males born preterm had lower cognitive scores and greater motor impairment compared with females, which may relate to differences in white matter maturation. The association between severe brain injury, early pain exposure, and neurodevelopmental outcomes was moderated by sex, indicating a differential response to early-life adversity in males and females born preterm.

Impact of neonatal hyperoxia on adult cardiac autonomic function in rats: Role of angiotensin II type 1 receptor activation

Individuals born preterm present altered cardiac autonomic function, a risk factor to heart diseases. Neonatal renin-angiotensin-system activation contributes to adult cardiomyopathy in rats exposed to neonatal hyperoxia, a well-established model of preterm birth-related conditions. Central angiotensin II receptor activation is a key modulator of the autonomic drive to the heart. Whether neonatal hyperoxia leads to alteration of the cardiac autonomic function through activation of the angiotensin II receptor type 1 (AT1) is unknown and was examined in the present study. Sprague-Dawley pups were exposed to hyperoxia or room air from postnatal days 3-10. AT1 antagonist losartan or water was given orally postnatal days 8-10. Blood pressure, autonomic function, left ventricular sympathetic innervation, β-adrenergic-receptors expression, and AT1 expression in the solitary-tract-nucleus were examined in adult rats. Neonatal hyperoxia led to loss of day-night blood pressure variation, decreased heart rate variability, increased sympathovagal balance, increased AT1 expression in the solitary-tract, decreased left ventricle sympathetic innervation, and increased β1-adrenergic-receptor protein expression. Losartan prevented the autonomic changes and AT1 expression in the solitary-tract but did not impact the loss of circadian blood pressure variation nor the changes in sympathetic innervation and in β1-adrenergic-receptor expression. In conclusion, neonatal hyperoxia leads to both central autonomic and cardiac sympathetic changes, partly programmed by neonatal activation of the renin-angiotensin system.

Should the sex of the fetus be considered when administering antenatal corticosteroids to preterm fetuses?

AIM

We aimed to determine whether the effect of antenatal corticosteroids (ANS) differs in male and female fetuses without anomalies born before 32 weeks in terms of mortality and short-term morbidity.

METHODS

This single-center retrospective study included infants born before 32 weeks' gestation and admitted to the neonatal intensive care unit between January 1, 2018, and December 31, 2020.

RESULTS

The study included 210 infants with a median gestational age of 28.6 weeks (24-31.6), a birth weight of 1065 g (445-2165), and an ANS use rate of 80%. Compared to female fetuses exposed to ANS, male fetuses exposed to ANS had a lower mortality rate (23% and 11%, respectively, p = 0.038), but there were no differences in intraventricular hemorrhage, retinopathy of prematurity, necrotizing enterocolitis, respiratory distress syndrome, and APGAR scores of 1st and 5th but an increased rate of bronchopulmonary dysplasia (moderate/severe) (p = 0.008). In addition, the mortality rate was similar in exposed and unexposed female fetuses (p = 0.850). Enzyme activities and steroid levels in the placenta might be different in male and female fetuses, which could explain the results of ANS administration.

CONCLUSIONS

In our study, we have shown that ANS has no effect on mortality in female fetuses younger than 32 weeks. Future studies may focus on adjusting the administration of ANS based on fetal sex, altering the dose or taking fetal sex into account when performing ANS.

What about sex, race(ism), and social determinants of health in neonatal outcomes?

Neonatal outcomes encompass a range of outcome measures, including mortality rates, physical and mental health morbidities, and long-term neurodevelopmental statistics. These outcomes are influenced by non-modifiable factors, such as sex and race, and modifiable factors, such as social determinants of health and racism. There is a known bias toward worse outcomes for male infants in terms of preterm birth, low birth weight, and mortality, with several biological and physiological factors contributing to these sex-related differences. In relation to racial disparities, wherein race is a social construct, maternal and infant healthcare continues to lag behind for minority populations compared with the white population, despite advances in medical care. Infants born to Black women have higher infant mortality rates and lower birth weights than infants of white women. These differences can be largely attributed to social and environmental factors, rather than racial and ethnic differences. Furthermore, we emphasize the role of social determinants of health in neonatal outcomes. Factors such as economic stability, education access and quality, healthcare access and quality, the physical neighborhood environment, and the social and community context all contribute to these outcomes. Overall, this article highlights the complex interactions between sex, race(ism), and social determinants of health in neonatal outcomes. It underscores the need for a comprehensive understanding of these factors to improve maternal-neonatal care and reduce disparities in outcomes. Healthcare providers, policymakers, and communities need to work together to combat these complex issues and improve neonatal outcomes for all infants, while understanding the complex interplay between sex, racism, and/or social determinants of health.

Gestational PBDE concentrations, persistent externalizing, and emerging internalizing behaviors in adolescents: The HOME study

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental chemicals used as flame retardants in commercial and consumer products. Gestational PBDE concentrations are associated with adverse behaviors in children; however, the persistence of these associations into adolescence remains understudied.

OBJECTIVE

We estimated the association of gestational PBDE serum concentrations with early adolescent self- and caregiver-reported behaviors at age 12 years and determined the consistency with previously observed associations in childhood with caregiver-reported behaviors in a prospective pregnancy and birth cohort.

METHODS

We measured maternal serum concentrations of five individual PBDE congeners and created a summary exposure variable (∑5BDE: 28, -47, -99, -100 and -153) during pregnancy. At age 12 years, we assessed behaviors for 237 adolescents using self- and caregiver-reports with the Behavioral Assessment System for Children-3 (BASC3). We used multivariable linear regression models to estimate covariate-adjusted associations of lipid standardized, log10-transformed gestational PBDE concentrations with BASC3 scores. We obtained estimates and 95% confidence intervals through a bootstrapping approach. We evaluated potential effect measure modification (EMM) of adolescent sex by examining sex-stratified regression models and estimating the EMM p-values.

RESULTS

Gestational PBDE concentrations were positively associated with adolescent-reported BASC3 composite indices for inattention & hyperactivity (BDE-28, -47, -99, -100, ∑5BDE), internalizing problems (BDE-28, -47, -99), functional impairment (BDE-28, ∑5BDE), and emotional symptoms (BDE-28). Gestational PBDE concentrations were positively associated with caregiver-reported BASC3 composite indices for externalizing problems (BDE-28, -47, -99, -100, -153, ∑5BDE) and behavioral symptoms (BDE-99). For caregiver reported behaviors, we observed stronger associations with gestational BDE concentrations among males, especially for executive functioning (BDE-28, -47, -99, -100, ∑5BDE).

DISCUSSION

Gestational PBDE serum concentrations were associated with self-reported internalizing and externalizing behavior problems in early adolescence. Caregiver-reported externalizing behaviors recognized during childhood remain associated with gestational PBDE concentrations and persist into early adolescence. Internalizing behaviors were less recognized by caregivers.

Sex-Specific Differences in the Relationship Between Prematurity and Ocular Geometry

Purpose

To explore differences in the relationship between gestational age (GA) and birth weight (BW) percentile and ocular geometry between males and females.

Methods

The Gutenberg Prematurity Eye Study involved a prospective ophthalmic examination of adults, aged 18 to 52 years, who were born preterm or at term, in Germany. The associations between GA and BW percentile on the main outcome measures were evaluated by uni- and multivariable linear regression analyses. The main outcome measures were central corneal thickness, corneal radius, anterior chamber depth, lens thickness, posterior segment length, and central foveal thickness. Potential sex-specific differences and an effect modification by sex were analyzed.

Results

This study involved 438 participants (245 females, 193 males) with an average age of 28.6 ± 8.7 years. In female participants, central foveal thickness was negatively associated with a higher GA (B = -2.99; P < 0.001). Similarly, male participants also demonstrated a negative association between central foveal thickness and GA (B = -4.27; P < 0.001). The multivariable model with effect modification revealed that the central foveal thickness was thicker with lower GA. There was an association between the effect modification of GA with sex and central foveal thickness, demonstrating a more pronounced effect of GA on central foveal thickness in male participants (B = 1.29; P = 0.04).

Conclusions

This study identified a sex-specific correlation between lower GA and thicker central foveal thickness, suggesting differences in the developmental trajectory of this biometric parameter concerning GA. A thicker central foveal thickness might affect the visual acuity of individuals born preterm in adulthood, with a more pronounced impact in males and a potential predisposition to age-related diseases later in life. Sex did not influence the association of GA or BW percentile to other ocular geometric parameters.

Perinatal compromise affects development, form, and function of the hippocampus part two; preclinical studies

The hippocampus is a vital brain structure deep in the medial temporal lobe that mediates a range of functions encompassing emotional regulation, learning, memory, and cognition. Hippocampal development is exquisitely sensitive to perturbations and adverse conditions during pregnancy and at birth, including preterm birth, fetal growth restriction (FGR), acute hypoxic-ischaemic encephalopathy (HIE), and intrauterine inflammation. Disruptions to hippocampal development due to these conditions can have long-lasting functional impacts. Here, we discuss a range of preclinical models of prematurity and FGR and conditions that induce hypoxia and inflammation, which have been critical in elucidating the underlying mechanisms and cellular and subcellular structures implicated in hippocampal dysfunction. Finally, we discuss potential therapeutic targets to reduce the burden of these perinatal insults on the developing hippocampus. IMPACT: The review explores the preclinical literature examining the association between pregnancy and birth complications, and hippocampal form and function. The developmental processes and cellular mechanisms that are disrupted within the hippocampus following perinatal compromise are described, and potential therapeutic targets are discussed.

Estimation of the causal effect of sex on neonatal intensive care unit outcomes among very low birth weight infants

OBJECTIVE

Estimate the causal effect of sex on outcomes in the neonatal intensive care unit (NICU) among very low birth weight (VLBW) infants.

STUDY DESIGN

Retrospective cohort study using Vermont Oxford Network data to compare NICU outcomes for VLBW males versus females. Odds ratios (OR) for outcomes that differed significantly by sex were computed using standard unweighted analysis and inverse probability weighted (IPW) analysis to correct for selection bias.

RESULTS

Using standard analysis, males were significantly more likely to die before discharge and experience six other adverse outcomes. From IPW analysis, male sex caused a 56% increase in the odds of death before discharge (OR = 1.56, 95% confidence interval: 1.18-1.94). Standard unweighted results were significantly biased towards increased risk of adverse outcomes for males (p = 0.005) compared to IPW results for which three outcomes were no longer significantly associated with male sex.

CONCLUSION

Standard statistical methods generally overestimate the casual effect of sex among VLBW infants.

Premature Babies Can Be Cared for in the Maternity Ward without an Increased Risk and Discharged with a Feeding Tube If Necessary

In general, premature babies are discharged home when they reach full self-feeding. We established a discharge management protocol which allows for discharging late preterm babies with a feeding tube if necessary. This retrospective study included 108 preterm infants (34+ weeks) born in 2019 and 2020. The preterm infants discharged with a feeding tube (n = 32) were born at 35.23 weeks' gestation (±0.884), with a birth weight of 2423 g (±375.1), and were discharged at 7.22 days (±3.63) and had a weight of 3466 g (±591.3) at the first outpatient visit around the expected birth date. The preterm infants discharged without a feeding tube were born at 35.97 weeks' gestation (±0.702) with a birth weight of 2589 g (±424.84), discharged home at 6.82 days (±7.11) and a weight of 3784 g (±621.8) at the first outpatient visit. The gestational week and birth weight were statistically significantly different between the groups, with a p-value of <0.001 for each, and the length of hospital stay (p = 0.762) and weight at follow-up (p = 0.064) did not significantly differ. No infant required tube-feeding at the time of the first outpatient visit, i.e., the time of expected birth. Therefore, with well-thought-out management, it is possible and safe to discharge preterm infants home with a feeding tube.

TrkB-mediated sustained neuroprotection is sex-specific and Erα-dependent in adult mice following neonatal hypoxia ischemia

BACKGROUND

Neonatal hypoxia ischemia (HI) related brain injury is one of the major causes of life-long neurological morbidities that result in learning and memory impairments. Evidence suggests that male neonates are more susceptible to the detrimental effects of HI, yet the mechanisms mediating these sex-specific responses to neural injury in neonates remain poorly understood. We previously tested the effects of treatment with a small molecule agonist of the tyrosine kinase B receptor (TrkB), 7,8-dihydroxyflavone (DHF) following neonatal HI and determined that females, but not males exhibit increased phosphorylation of TrkB and reduced apoptosis in their hippocampi. Moreover, these female-specific effects of the TrkB agonist were found to be dependent upon the expression of Erα. These findings demonstrated that TrkB activation in the presence of Erα comprises one pathway by which neuroprotection may be conferred in a female-specific manner. The goal of this study was to determine the role of Erα-dependent TrkB-mediated neuroprotection in memory and anxiety in young adult mice exposed to HI during the neonatal period.

METHODS

In this study, we used a unilateral hypoxic ischemic (HI) mouse model. Erα+/+ or Erα-/- mice were subjected to HI on postnatal day (P) 9 and mice were treated with either vehicle control or the TrkB agonist, DHF, for 7 days following HI. When mice reached young adulthood, we used the novel object recognition, novel object location and open field tests to assess long-term memory and anxiety-like behavior. The brains were then assessed for tissue damage using immunohistochemistry.

RESULTS

Neonatal DHF treatment prevented HI-induced decrements in recognition and location memory in adulthood in females, but not in males. This protective effect was absent in female mice lacking Erα. The female-specific improved recognition and location memory outcomes in adulthood conferred by DHF therapy after neonatal HI tended to be or were Erα-dependent, respectively. Interestingly, DHF triggered anxiety-like behavior in both sexes only in the mice that lacked Erα. When we assessed the severity of injury, we found that DHF therapy did not decrease the percent tissue loss in proportion to functional recovery. We additionally observed that the presence of Erα significantly reduced overall HI-associated mortality in both sexes.

CONCLUSIONS

These observations provide evidence for a therapeutic role for DHF in which TrkB-mediated sustained recovery of recognition and location memories in females are Erα-associated and dependent, respectively. However, the beneficial effects of DHF therapy did not include reduction of gross tissue loss but may be derived from the enhanced functioning of residual tissues in a cell-specific manner.

Sex-based differences in placental DNA methylation profiles related to gestational age: an NIH ECHO meta-analysis

The placenta undergoes many changes throughout gestation to support the evolving needs of the foetus. There is also a growing appreciation that male and female foetuses develop differently in utero, with unique epigenetic changes in placental tissue. Here, we report meta-analysed sex-specific associations between gestational age and placental DNA methylation from four cohorts in the National Institutes of Health (NIH) Environmental influences on Child Health Outcomes (ECHO) Programme (355 females/419 males, gestational ages 23-42 weeks). We identified 407 cytosine-guanine dinucleotides (CpGs) in females and 794 in males where placental methylation levels were associated with gestational age. After cell-type adjustment, 55 CpGs in females and 826 in males were significant. These were enriched for biological processes critical to the immune system in females and transmembrane transport in males. Our findings are distinct between the sexes: in females, associations with gestational age are largely explained by differences in placental cellular composition, whereas in males, gestational age is directly associated with numerous alterations in methylation levels.

Influence of fetal gender on overall perinatal outcome: a prospective observational study

BACKGROUND

Fetal gender is considered as one of significant predictors of pregnancy and perinatal outcome. The aim of this study is to assess impact of fetal gender on perinatal outcome.

METHODS

Present observational study was conducted in Obstetrics and Gynecology department of rural tertiary center of Northern India over one year (January-December 2018) on all randomly selected antenatal women at gestation ≥28 weeks, delivering by any route (cesarean/vaginal) and fulfilling inclusion criteria were enrolled. Immediately after delivery, neonatal birth weight was measured using table top beam weighing scale. Apgar scores at 1- and 5-minutes, Neonatal Intensive Care Unit admission, neonatal complications were assessed by pediatrician. Adverse perinatal outcome including neonatal morbidities (prematurity, neonatal intensive care unit admission, neonatal complications) and perinatal mortality were compared between two genders. Statistical analysis was done using SPSS 22 version software.

RESULTS

Of 3085 delivered neonates, 1450 (47%) were females, 1,633(52.9%) males and two (0.06%) had ambiguous genitalia, hence excluded. Mean values for neonatal birth weight for males was 2.77±0.540 kg and females 2.65±0.506 kg (P=0.0000). One- and 5-minute Apgar scores for male neonate were 6.81±1.565, 8.51±1.841 and for females 6.98±1.184, 8.70±1.383, respectively (P=0.001). NICU admission rate, need for oxygen and intubation, complications were significantly higher for male neonates (P<0.05) whereas females had higher incidence of intra-uterine growth restriction (P=0.000). Intra-uterine deaths were also more common with male gender (P=0.007). No significant difference was observed between two genders in relation to gestation at birth (P>0.05).

CONCLUSIONS

Male neonates had higher birth weight, but adverse perinatal outcome as compared to females.

Outcomes at 18-24 Months of Infants with Birth Weight under 500 g Born in Korea during 2013-2017: A Nationwide Cohort Study

INTRODUCTION

This study aimed to investigate the outcomes of infants at 18-24 months born in the Korean Neonatal Network with a birth weight <500 g.

METHODS

The anthropometric and neurodevelopmental data of infants with a birth weight <500 g at a gestational age of ≥22 weeks who were registered in the Korean Neonatal Network 2013-2017 and followed up at a corrected age of 18-24 months were reviewed. Neurodevelopmental impairment was defined as the presence of any of the following: (1) cerebral palsy; (2) severe visual impairment; (3) hearing impairment; or (4) cognitive impairment. Cognitive impairment was defined as (1) a Bayley Scales of Infant Development-II Mental Development Index score <70; and (2) Bayley Scales of Infant and Toddler Development-III Cognitive and Language Composite scores <85. Cognitive testing was performed for infants with suspected problems upon clinician's referral to developmental specialists.

RESULTS

At a median corrected age of 20 months, 26/52 (50%) of included infants had neurodevelopmental impairment. Cerebral palsy, severe visual impairment, wearing of glasses, hearing impairment, and cognitive impairment occurred in 22%, 0%, 8%, 5%, and 57% of the included infants, respectively. The proportions of infants with <2 standard deviations of weight, length, and head circumference were 54%, 52%, and 56%, respectively. The majority (70%) of infants were rehospitalized, and the most common cause was respiratory problems.

CONCLUSION

Half of infants with a birth weight <500 g in Korea may exhibit neurodevelopmental impairment and growth retardation at a corrected age of 18-24 months. Multidisciplinary follow-up along with continuous rehabilitation will be needed to improve neurological and physical development in this special population.

MR imaging and outcome in neonatal HIBD models are correlated with sex: the value of diffusion tensor MR imaging and diffusion kurtosis MR imaging

Objective

Hypoxic-ischemic encephalopathy can lead to lifelong morbidity and premature death in full-term newborns. Here, we aimed to determine the efficacy of diffusion kurtosis (DK) [mean kurtosis (MK)] and diffusion tensor (DT) [fractional anisotropy (FA), mean diffusion (MD), axial diffusion (AD), and radial diffusion (RD)] parameters for the early diagnosis of early brain histopathological changes and the prediction of neurodegenerative events in a full-term neonatal hypoxic-ischemic brain injury (HIBD) rat model.

Methods

The HIBD model was generated in postnatal day 7 Sprague-Dawley rats to assess the changes in DK and DT parameters in 10 specific brain structural regions involving the gray matter, white matter, and limbic system during acute (12 h) and subacute (3 d and 5 d) phases after hypoxic ischemia (HI), which were validated against histology. Sensory and cognitive parameters were assessed by the open field, novel object recognition, elevated plus maze, and CatWalk tests.

Results

Repeated-measures ANOVA revealed that specific brain structures showed similar trends to the lesion, and the temporal pattern of MK was substantially more varied than DT parameters, particularly in the deep gray matter. The change rate of MK in the acute phase (12 h) was significantly higher than that of DT parameters. We noted a delayed pseudo-normalization for MK. Additionally, MD, AD, and RD showed more pronounced differences between males and females after HI compared to MK, which was confirmed in behavioral tests. HI females exhibited anxiolytic hyperactivity-like baseline behavior, while the memory ability of HI males was affected in the novel object recognition test. CatWalk assessments revealed chronic deficits in limb gait parameters, particularly the left front paw and right hind paw, as well as poorer performance in HI males than HI females.

Conclusions

Our results suggested that DK and DT parameters were complementary in the immature brain and provided great value in assessing early tissue microstructural changes and predicting long-term neurobehavioral deficits, highlighting their ability to detect both acute and long-term changes. Thus, the various diffusion coefficient parameters estimated by the DKI model are powerful tools for early HIBD diagnosis and prognosis assessment, thus providing an experimental and theoretical basis for clinical treatment.

Postnatal growth restriction and neurodevelopment at 5 years of age: a European extremely preterm birth cohort study

OBJECTIVE

To investigate whether extrauterine growth restriction (EUGR) during the neonatal hospitalisation by sex among extremely preterm (EPT) infants is associated with cerebral palsy (CP) and cognitive and motor abilities at 5 years of age.

STUDY DESIGN

Population-based cohort of births <28 weeks of gestation with data from obstetric and neonatal records and parental questionnaires and clinical assessments at 5 years of age.

SETTING

11 European countries.

PATIENTS

957 EPT infants born in 2011-2012.

MAIN OUTCOMES

EUGR at discharge from the neonatal unit was defined as (1) the difference between Z-scores at birth and discharge with <-2 SD as severe, -2 to -1 SD as moderate using Fenton's growth charts (Fenton) and (2) average weight-gain velocity using Patel's formula in grams (g) per kilogram per day (Patel) with <11.2 g (first quartile) as severe, 11.2-12.5 g (median) as moderate. Five-year outcomes were: a CP diagnosis, intelligence quotient (IQ) using the Wechsler Preschool and Primary Scales of Intelligence tests and motor function using the Movement Assessment Battery for Children, second edition.

RESULTS

40.1% and 33.9% children were classified as having moderate and severe EUGR, respectively, by Fenton and 23.8% and 26.3% by Patel. Among children without CP, those with severe EUGR had lower IQ than children without EUGR (-3.9 points, 95% Confidence Interval (CI)=-7.2 to -0.6 for Fenton and -5.0 points, 95% CI=-8.2 to -1.8 for Patel), with no interaction by sex. No significant associations were observed between motor function and CP.

CONCLUSIONS

Severe EUGR among EPT infants was associated with decreased IQ at 5 years of age.

Sexually dimorphic methylation patterns characterize the placenta and blood from extremely preterm newborns

BACKGROUND

Health outcomes among children born prematurely are known to be sexually dimorphic, with male infants often more affected, yet the mechanism behind this observation is not clear. CpG methylation levels in the placenta and blood also differ by sex and are associated with adverse health outcomes. We contrasted CpG methylation levels in the placenta and neonatal blood (n = 358) from the Extremely Low Gestational Age Newborn (ELGAN) cohort based on the EPIC array, which assays over 850,000 CpG sites across the epigenome. Sex-specific epigenome-wide association analyses were conducted for the placenta and neonatal blood samples independently, and the results were compared to determine tissue-specific differences between the methylation patterns in males and females. All models were adjusted for cell type heterogeneity. Enrichment pathway analysis was performed to identify the biological functions of genes related to the sexually dimorphic CpG sites.

RESULTS

Approximately 11,500 CpG sites were differentially methylated in relation to sex. Of these, 5949 were placenta-specific and 5361 were blood-specific, with only 233 CpG sites overlapping in both tissues. For placenta-specific CpG sites, 90% were hypermethylated in males. For blood-specific CpG sites, 95% were hypermethylated in females. In the placenta, keratinocyte differentiation biological pathways were enriched among the differentially methylated genes. No enrichment pathways were observed for blood.

CONCLUSIONS

Distinct methylation patterns were observed between male and female children born extremely premature, and keratinocyte differentiation pathways were enriched in the placenta. These findings provide new insights into the epigenetic mechanisms underlying sexually dimorphic health outcomes among extremely premature infants.

Global, regional, and national burden of preterm birth attributable to ambient and household PM2.5 from 1990 to 2019: Worsening or improving?

BACKGROUND

Maternal exposure to fine particular matter (PM_2.5) during pregnancy, including ambient and household PM_2.5, has been linked with increased risk of preterm birth (PTB). However, the global spatio-temporal distribution of PTB-related deaths and disability-adjusted life years (DALYs) attributable to PM_2.5 is not well documented. We estimated the global, regional, and national patterns and trends of PTB burden attributable to both ambient and household PM_2.5 from 1990 to 2019.

METHODS

Based on the Global Burden of Disease Study (GBD) 2019 database, we obtained the numbers of deaths and DALYs as well as age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) of PTB attributable to total, ambient, and household PM_2.5 by socio-demographic index (SDI) and sex during 1990-2019. The average annual percentage changes (AAPCs) were calculated to assess the temporal trends of attributable burdens.

RESULTS

In 2019, 126,752 deaths and 11.3 million DALYs related to PTB worldwide (two-thirds in Western Sub-Saharan Africa and South Asia) could be caused by excess PM_2.5 above the theoretical minimum-risk exposure level (TMREL), of which 39 % and 61 % were attributable to ambient PM_2.5 and household PM_2.5, respectively. From 1990 to 2019, the global ASMR due to ambient PM_2.5 increased slightly by 7.08 % whereas that due to household PM_2.5 decreased substantially by 58.81 %, although the latter still dominated the attributable PTB burden, especially in low and low-middle SDI regions. Similar results were also observed for ASDRs. In addition, PTB burden due to PM_2.5 was higher in male infants and in lower SDI regions.

CONCLUSIONS

Globally in 2019, PM_2.5 remains a great concern on the PTB burden, especially in Western Sub-Saharan Africa and South Asia. Between 1990 and 2019, age-standardized burden of PTB due to ambient PM_2.5 increased globally, while that due to household PM_2.5 decreased markedly but still dominated in low and low-middle SDI regions.

Essential Fatty Acid Supplementation and Early Inflammation in Preterm Infants: Secondary Analysis of a Randomized Clinical Trial

INTRODUCTION

Postnatal inflammation is associated with increased mortality and adverse outcomes in preterm infants. The essential fatty acids arachidonic acid (ARA) and docosahexaenoic acid (DHA) are precursors of lipid mediators with a key role in resolving inflammation. Our aim was to investigate the effect of ARA and DHA supplementation on systemic inflammation in very preterm infants and to identify clinical factors associated with early inflammation.

METHODS

Secondary analysis of data from a randomized clinical trial (ImNuT study). Infants with gestational age (GA) less than 29 weeks were randomized to receive a daily enteral supplement with ARA 100 mg/kg and DHA 50 mg/kg (ARA:DHA group) or MCT oil (control group) from the second day of life to 36 weeks postmenstrual age. ARA, DHA, and four proinflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) were analyzed in repeated dried blood samples from birth to day 28 and the area under the curve (AUC) for each variable was calculated.

RESULTS

The intention to treat population included 120 infants with mean (SD) GA 26.4 (1.7). The ARA:DHA group had significantly lower IL-6 levels from day 3 to day 28 compared to the control group, mean difference AUC log10 (95% CI): 0.16 (0.03-0.30) pg/mL, p = 0.018. There was no correlation between ARA or DHA blood concentrations and cytokine levels. Having a low gestational age was independently associated with increased levels of all cytokines during the first 4 weeks of life.

CONCLUSIONS

Enhanced supplementation with ARA and DHA may modulate inflammation in very preterm infants.

Influence of sex on the requirement for and outcomes following late postnatal corticosteroid treatment

There remains a disparity between the outcomes of male and female prematurely born infants. Our aim was to assess the influence of sex on the requirement for late (> 7 days) postnatal corticosteroid (PNS) treatment and the outcomes following treatment. A retrospective whole population study of infants born at less than 28 weeks of gestation in all neonatal units in England between 2014 and 2018. The impact of exposure to at least five consecutive days of dexamethasone or hydrocortisone on bronchopulmonary dysplasia (BPD) at 36 weeks corrected gestation and survival to discharge from neonatal care was determined. Ten thousand, six hundred and fifty-five infants survived to seven days. Male sex was associated with an increased incidence of BPD (OR 1.41, 95%CI 1.287-1.552, p < 0.001) and death (OR 1.227, 95%CI 1.123-1.452, p < 0.001). Two thousand, three hundred and forty-four infants (22%) received at least one course of PNS at a median of 23 (IQR 15-40) days after birth. Males (23.6%) were more likely to receive PNS than females (20.1%), p < 0.001 and receive repeated courses (mean 1.67 compared to a mean of 1.59 in the females), p = 0.027. Multivariate regression analysis identified no significant differences in the incidence of BPD or death between male and females who received PNS.  Conclusions: Males and females had similar outcomes after receiving PNS, but a significantly greater proportion of males met the clinical threshold to receive PNS and were more likely to receive repeated courses which may expose them to a greater risk of adverse long-term outcomes. What is Known: • There remains a difference in outcomes of male and female infants born prematurely. • Prematurely born male infants were more likely to receive postnatal corticosteroids and a greater number of courses but had similar outcomes compared to female infants. What is New: • Postnatal corticosteroids have long-term adverse effects. Such outcomes should be considered when weighing up the risk-benefit ratio of prescribing postnatal corticosteroids, particularly in very prematurely born male infants.

Senatorial signatures Absence of male-female differences in left-handedness

A greater frequency of left-handedness among males than females has been observed in general populations. Past studies have explained this difference with reference to males' greater susceptibility to adverse birth events, while more recent studies have identified other contributing factors. On January 16, 2020, U.S. senators signed an oath to act impartially during the president's impeachment trial. This televised event allowed direct comparison of the proportion of right-handedness and left-handedness in a professionally accomplished sample of males and females. As expected, no sex difference in the proportion of left-handed senators was found, although the small sample size offered low statistical power. Replicating this finding with a larger sample would support the view that left-handedness among select groups of males is linked to genetic factors.

Sex-Linked Differences in Malaria Risk Across the Lifespan

Despite the high burden of malaria worldwide, there is surprisingly scarce research on sex-based differences in malaria outside of pregnancy. A more thorough understanding of sexual dimorphism in malaria, and what underlies these sex-based differences, could elucidate the underlying mechanisms driving malaria pathogenesis and has the potential to inform malaria control efforts, including new vaccines. This review summarizes our current understanding of sex-based differences in the epidemiology of malaria across the lifespan, potential sex- or gender-based mechanisms driving these differences, and the knowledge gaps that need to be addressed.

Aberrant allometric scaling of cortical folding in preterm-born adults

A universal allometric scaling law has been proposed to describe cortical folding of the mammalian brain as a function of the product of cortical surface area and the square root of cortical thickness across different mammalian species, including humans. Since these cortical properties are vulnerable to developmental disturbances caused by preterm birth in humans and since these alterations are related to cognitive impairments, we tested (i) whether cortical folding in preterm-born adults follows this cortical scaling law and (ii) the functional relevance of potential scaling aberrances. We analysed the cortical scaling relationship in a large and prospectively collected cohort of 91 very premature-born adults (<32 weeks of gestation and/or birthweight <1500 g, very preterm and/or very low birth weight) and 105 full-term controls at 26 years of age based on the total surface area, exposed surface area and average cortical thickness measured with structural magnetic resonance imaging and surface-based morphometry. We found that the slope of the log-transformed cortical scaling relationship was significantly altered in adults (very preterm and/or very low birth weight: 1.24, full-term: 1.14, P = 0.018). More specifically, the slope was significantly altered in male adults (very preterm and/or very low birth weight: 1.24, full-term: 1.00, P = 0.031), while there was no significant difference in the slope of female adults (very preterm and/or very low birth weight: 1.27, full-term: 1.12, P = 0.225). Furthermore, offset was significantly lower compared with full-term controls in both male (very preterm and/or very low birth weight: -0.546, full-term: -0.538, P = 0.001) and female adults (very preterm and/or very low birth weight: -0.545, full-term: -0.538, P = 0.023), indicating a systematic shift of the regression line after preterm birth. Gestational age had a significant effect on the slope in very preterm and/or very low birth weight adults and more specifically in male very preterm and/or very low birth weight adults, indicating that the difference in slope is specifically related to preterm birth. The shape or tension term of the scaling law had no significant effect on cognitive performance, while the size of the cortex did. Results demonstrate altered scaling of cortical surface and cortical thickness in very premature-born adults. Data suggest altered mechanical forces acting on the cortex after preterm birth.

Influence of antenatal corticosteroids and sex on the mortality and morbidity of extremely prematurely born infants

OBJECTIVE

To report the effect of antenatal corticosteroids (ANS) on mortality, intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD) and the duration of ventilation according to sex in extremely preterm infants.

METHODS

All extremely preterm infants admitted to any neonatal unit in England between 2014 and 2019.

RESULTS

Eleven thousand seven hundred and fourteen infants (54% male) were included with a median (IQR) gestational age of 26 + 1 (24 + 6 - 27 + 1) weeks, birth weight of 809 (670 - 960) grams and birth weight z-score of -0.38 (-0.88 to 0.07). ANS were administered in 10,449 infants (89%); equally in males and females. Infants who received ANS compared to those who did not, had a lower mortality before discharge (18.7 versus 32.3%, p < .001), a lower incidence of IVH grade III-IV (14.5 versus 25.5%, p < .001) and a shorter median (IQR) duration of mechanical ventilation [10 (3-27) versus 13 (5-31) days, p < .001]. Female compared to male infants had a lower mortality (18.7 versus 21.7%, p < .001), a lower incidence of IVH grade III-IV (10.9 versus 13.9%, p < .001), a lower incidence of bronchopulmonary dysplasia (61.6 versus 68.2%, p= <.001) and a shorter median (IQR) duration of mechanical ventilation days [9 (3-26) versus 13 (4-29) days, p= <.001]. In females, the risk of dying before discharge from hospital was greater in those who did not receive ANS (odds ratio (OR) 1.81, 95% CI 1.35-2.44) than in those who did (OR 0.55, 95% CI 0.41-0.74). In males the risk of dying was also greater in those that did not receive ANS (OR 1.36, 95% CI 1.03-1.77) compared to those who did (OR 0.74, 95% CI 0.57-0.96).

CONCLUSION

Antenatal corticosteroids had a greater beneficial effect in female compared to male extremely prematurely born infants in reducing death before discharge.

Survival status and predictors of mortality among low-birthweight neonates admitted to KMC units of five public hospitals in Ethiopia: Frailty survival regression model

BACKGROUND

Low birth weight (LBW) and preterm birth are leading causes of under-five and neonatal mortality globally. Data about the timing of death and outcomes for LBW and preterm births are limited in Ethiopia and could be used to strengthen neonatal healthcare. This study describes the incidence of neonatal mortality rates (NMR) stratified by newborn size at birth for gestational age and identifies its predictors at five public hospitals in Ethiopia.

METHODS

A prospective follow-up study enrolled 808 LBW neonates from March 2017 to February 2019. Sex-specific birthweight for gestational age percentile was constructed using Intergrowth 21st charts. Mortality patterns by birthweight for-gestational-age-specific survival curves were compared using the log-rank test and Kaplan-Meier survival curves. A random-effects frailty survival model was employed to identify predictors of time to death.

RESULTS

Among the 808 newborns, the birthweight distribution was 3.2% <1000 g, 28.3% <1500 g, and 68.1% <2000 g, respectively. Birthweight for gestational age categories were 40.0% both preterm and small for gestational age (SGA), 20.4% term SGA, 35.4% appropriate weight for gestational age, and 4.2% large for gestational age (LGA). The sample included 242 deaths, of which 47.5% were both preterm and SGA. The incidence rate of mortality was 16.17/1000 (95% CI 14.26-18.34) neonatal-days of observation. Neonatal characteristics independently related to increased risk of time-to-death were male sex (adjusted hazards ratio [AHR] 3.21 95% CI 1.33-7.76), born preterm (AHR 8.56 95% CI 1.59-46.14), having been diagnosed with a complication (AHR 4.68 95% CI 1.49-14.76); some maternal characteristics and newborn care practices (like lack of effective KMC, AHR 3.54 95% CI 1.14-11.02) were also significantly associated with time-to-death.

CONCLUSIONS

High mortality rates were measured for low birthweight neonates-especially those both preterm and SGA births-even in the context of tertiary care. These findings highlight the need for improved quality of neonatal care, especially for the smallest newborns.

Therapeutic Interventions in Rat Models of Preterm Hypoxic Ischemic Injury: Effects of Hypothermia, Caffeine, and the Influence of Sex

Infants born prematurely have an increased risk of experiencing brain injury, specifically injury caused by Hypoxia Ischemia (HI). There is no approved treatment for preterm infants, in contrast to term infants that experience Hypoxic Ischemic Encephalopathy (HIE) and can be treated with hypothermia. Given this increased risk and lack of approved treatment, it is imperative to explore and model potential treatments in animal models of preterm injury. Hypothermia is one potential treatment, though cooling to current clinical standards has been found to be detrimental for preterm infants. However, mild hypothermia may prove useful. Caffeine is another treatment that is already used in preterm infants to treat apnea of prematurity, and has shown neuroprotective effects. Both of these treatments show sex differences in behavioral outcomes and neuroprotective effects, which are critical to explore when working to translate from animal to human. The effects and research history of hypothermia, caffeine and how sex affects these treatment outcomes will be explored further in this review article.

Influence of Neonatal Sex on Breast Milk Protein and Antioxidant Content in Spanish Women in the First Month of Lactation

Breast milk (BM) is the best food for newborns. Male sex is associated with a higher risk of fetal programming, prematurity, and adverse postnatal outcome, being that BM is an important health determinant. BM composition is dynamic and modified by several factors, including lactation period, prematurity, maternal nutritional status, and others. This study was designed to evaluate the influence of sex on BM composition during the first month of lactation, focused on macronutrients and antioxidants. Forty-eight breastfeeding women and their fifty-five newborns were recruited at the Hospital Clínico San Carlos (Madrid, Spain). Clinical sociodemographic data and anthropometric parameters were collected. BM samples were obtained at days 7, 14, and 28 of lactation to assess fat (Mojonnier method), protein (Bradford method), and biomarkers of oxidative status: total antioxidant capacity (ABTS and FRAP methods), thiol groups, reduced glutathione, superoxide dismutase and catalase activities, lipid peroxidation, and protein oxidation (spectrophotometric methods). Linear mixed models with random effects adjusted by maternal anthropometry, neonatal Z-scores at birth, and gestational age were used to assess the main effects of sex, lactation period, and their interaction. BM from mothers with male neonates exhibited significantly higher protein, ABTS, FRAP, and GSH levels, while catalase showed the opposite trend. No differences between sexes were observed in SOD, total thiols, and oxidative damage biomarkers. Most changes were observed on day 7 of lactation. Adjusted models demonstrated a significant association between male sex and proteins (β = 2.70 ± 1.20; p-Value = 0.048). In addition, total antioxidant capacity by ABTS (β = 0.11 ± 0.06) and GSH (β = 1.82 ± 0.94) showed a positive trend near significance (p-Value = 0.056; p-Value = 0.064, respectively). In conclusion, transitional milk showed sex differences in composition with higher protein and GSH levels in males. This may represent an advantage in the immediate perinatal period, which may help to counteract the worse adaptation of males to adverse intrauterine environments and prematurity.

Sex Differences in Patent Ductus Arteriosus Incidence and Response to Pharmacological Treatment in Preterm Infants: A Systematic Review, Meta-Analysis and Meta-Regression

A widely accepted concept in perinatal medicine is that boys are more susceptible than girls to complications of prematurity. However, whether this ‘male disadvantage of prematurity’ also involves persistent patent ductus arteriosus (PDA) has been scarcely investigated. Our aim was to conduct a systematic review and meta-analysis on studies addressing sex differences in the risk of developing PDA among preterm infants. We also investigated whether the response to pharmacological treatment of PDA differs between boys and girls. PubMed/Medline and Embase databases were searched. The random-effects male/female risk ratio (RR) and 95% confidence interval (CI) were calculated. We included 146 studies (357,781 infants). Meta-analysis could not demonstrate sex differences in risk of developing any PDA (37 studies, RR 1.03, 95% CI 0.97 to 1.08), hemodynamically significant PDA (81 studies, RR 1.00, 95% CI 0.97 to 1.02), or in the rate of response to pharmacological treatment (45 studies, RR 1.01, 95% CI 0.98 to 1.04). Subgroup analysis and meta-regression showed that the absence of sex differences was maintained over the years and in different geographic settings. In conclusion, both the incidence of PDA in preterm infants and the response rate to pharmacological treatment of PDA are not different between preterm boys and girls.

Differential expression of placental 11β-HSD2 induced by high maternal glucocorticoid exposure mediates sex differences in placental and fetal development

A variety of adverse environmental factors during pregnancy cause maternal chronic stress. Caffeine is a common stressor, and its consumption during pregnancy is widespread. Our previous study showed that prenatal caffeine exposure (PCE) increased maternal blood glucocorticoid levels and caused abnormal development of offspring. However, the placental mechanism for fetal development inhibition caused by PCE-induced high maternal glucocorticoid has not been reported. This study investigated the effects of PCE-induced high maternal glucocorticoid level on placental and fetal development by regulating placental 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2) expression and its underlying mechanism. First, human placenta and umbilical cord blood samples were collected from women without prenatal use of synthetic glucocorticoids. We found that placental 11β-HSD2 expression was significantly correlated with umbilical cord blood cortisol level and birth weight in male newborns but not in females. Furthermore, we established a rat model of high maternal glucocorticoids induced by PCE (caffeine, 60 mg/kg·d, ig), and found that the expression of 11β-HSD2 in male PCE placenta was decreased and negatively correlated with the maternal/fetal/placental corticosterone levels. Meanwhile, we found abnormal placental structure and nutrient transporter expression. In vitro, BeWo cells were used and confirm that 11β-HSD2 mediated inhibition of placental nutrient transporter expression induced by high levels of glucocorticoid. Finally, combined with the animal and cell experiments, we further confirmed that high maternal glucocorticoid could activate the GR-C/EBPα-Egr1 signaling pathway, leading to decreased expression of 11β-HSD2 in males. However, there was no significant inhibition of placental 11β-HSD2 expression, placental and fetal development in females. In summary, we confirmed that high maternal glucocorticoids could regulate placental 11β-HSD2 expression in a sex-specific manner, leading to differences in placental and fetal development. This study provides the theoretical and experimental basis for analyzing the inhibition of fetoplacental development and its sex difference caused by maternal stress.

Recent historic increase of infant mortality in France: A time-series analysis, 2001 to 2019

Background

The infant mortality rate (IMR) serves as a key indicator of population health.

Methods

We used data from the French National Institute of Statistics and Economic Studies on births and deaths during the first year of life from 2001 to 2019 to calculate IMR aggregated by month. We ran joinpoint regressions to identify inflection points and assess the linear trend of each segment. Exploratory analyses were performed for overall IMR, as well as by age at death subgroups (early neonatal [D0-D6], late neonatal [D7-27], and post-neonatal [D28-364]), and by sex. We performed sensitivity analyses by excluding deaths at D0 and using other time-series modeling strategies.

Results

Over the 19-year study period, 53,077 infant deaths occurred, for an average IMR of 3·63/1000 (4·00 in male, 3·25 in female); 24·4% of these deaths occurred during the first day of life and 47·8% during the early neonatal period. Joinpoint analysis identified two inflection points in 2005 and 2012. The IMR decreased sharply from 2001 to 2005 (slope: -0·0167 deaths/1000 live births/month; 95%CI: -0·0219 to -0·0116) and then decreased slowly between 2005 and 2012 (slope: -0·0041; 95%CI: -0·0065 to -0·0016). From 2012 onwards, a significant increase in IMR was observed (slope: 0·0033; 95%CI: 0·0011 to 0·0056). Subgroup analyses indicated that these trends were driven notably by an increase in the early neonatal period. Sensitivity analyses provided consistent results.

Interpretation

The recent historic increase in IMR since 2012 in France should prompt urgent in-depth investigation to understand the causes and prepare corrective actions.

Funding

No financial relationships with any organizations that might have an interest in the submitted work in the previous three years, no other relationships or activities that could appear to have influenced the submitted work.

Impact of COVID-19 Pandemic on Developmental Service Delivery in Children With a History of Neonatal Seizures

BACKGROUND

Children with a history of acute provoked neonatal seizures are at high risk for disability, often requiring developmental services. The coronavirus disease 2019 (COVID-19) pandemic has led to widespread changes in how health care is delivered. Our objective was to determine the magnitude of service interruption of among children born between October 2014 and December 2017 and enrolled in the Neonatal Seizure Registry (NSR), a nine-center collaborative of pediatric centers in the United States.

METHODS

This is a prospective cohort study of children with acute provoked seizures with onset ≤44 weeks' gestation and evaluated at age three to six years. Parents of children enrolled in the NSR completed a survey about their child's access to developmental services between June 2020 and April 2021.

RESULTS

Among 144 children enrolled, 72 children (50%) were receiving developmental services at the time of assessment. Children receiving services were more likely to be male, born preterm, and have seizure etiology of infection or ischemic stroke. Of these children, 64 (89%) experienced a disruption in developmental services due to the pandemic, with the majority of families (n = 47, 73%) reporting that in-person services were no longer available.

CONCLUSIONS

Half of children with acute provoked neonatal seizures were receiving developmental services at ages three to six years. The COVID-19 pandemic has led to widespread changes in delivery of developmental services. Disruptions in services have the potential to impact long-term outcomes for children who rely on specialized care programs to optimize mobility and learning.

Disparities in tracheostomies and gastrostomy tubes in infants at the edge of viability

OBJECTIVES

To assess trends of clinical practice of tracheostomy and gastrostomy tube (G-tube) placement over a 25-year period and to assess the association of both procedures with outcomes in extremely low birth weight (ELBW) infants (<1000 g).

METHODS

We reviewed and analyzed data obtained from the National Inpatient Sample dataset from 1993 to 2018. ELBW infants who received a tracheostomy and or G-tube were included. Regression analysis was performed to assess the association of tracheostomy and/or G-tube placement with mortality after controlling for confounding variables.

RESULTS

A total of 620,061 ELBW infants were identified in the weighted sample. Of them, 221,339 were included. G-tube was placed on 4867 (2.2%) infants, tracheostomy was placed on 1788 (0.8%) infants, and both procedures were placed on 1026 (0.46%). Mortality was highest (26.9%) in infants who received tracheostomy only and lowest (5.5%) in those who had G-tube only and (17.8%) in those who had both procedures with adjusted odds ratios of 7.1 (6.3-7.9), 0.7 (0.6-0.8), and 3.7 (3.1-4.4), respectively. The length of stay (LOS) was highest with the combined procedure (219 ± 171), and lowest in the nonintervention group (88 ± 57). The trend of G-tube placement has increased over the years (p < 0.01) but tracheostomy placement has decreased over time.

CONCLUSION

Tracheostomy is associated with increased mortality in ELBW infants and increased LOS in survivors whereas the placement of both tracheostomy and G-tube is independently associated with decreased mortality. Prospective studies are needed to assess the relationship between clinical presentation, the timing of the procedure, and outcomes.

The Tiniest Babies Registry: A registry of survivors born weighing less than 400 grams

The Tiniest Babies Registry was launched in the year 2000 as a web-based registry for patients who survived to discharge after being born with birth weights below 400 grams. The registry began with 15 patients and by January 2022 had grown to 291, ranging in birth weight from 212 to 399 grams and in gestational age from 21 to 34 weeks. Three patients were born in the 1930s, and no others were born until 1985. The greatest number in a single year was 21 in 2010. The infants were born in 16 countries, but 166 of 291 (57%) were born in the U.S. All except 10 of the infants were small for gestational age at birth. No systematic data on the long-term outcomes of these patients is available, but the information submitted by selected registry participants indicates they are at increased risk for continued delays in growth and development.

Risk factors for hospitalisation in Welsh infants with a congenital anomaly

OBJECTIVES

To investigate risk factor associated with hospitalisation of infants with a congenital anomaly in Wales, UK.

DESIGN

A population-based cohort study.

SETTING

Data from the Welsh Congenital Anomaly Register and Information Service linked to the Patient Episode Database for Wales and livebirths and deaths from the Office for National Statistics.

PATIENTS

All livebirths between 1999 and 2015 with a diagnosis of a congenital anomaly, which was defined as a structural, metabolic, endocrine or genetic defect, as well as rare diseases of hereditary origin.

MAIN OUTCOME MEASURES

Adjusted OR (aOR) associated with 1 or 2+ hospital admissions in infancy versus no admissions were estimated for sociodemographic, maternal and infant factors using multinomial logistic regression for the subgroups of all, isolated, multiple and cardiovascular anomalies.

RESULTS

25 523 infants affected by congenital anomalies experienced a total of 50 705 admissions in infancy. Risk factors for ≥2 admissions were younger maternal age ≤24 years (aOR: 1.17; 95% CI 1.06 to 1.30), maternal smoking (aOR: 1.20; 1.10 to 1.31), preterm birth (aOR: 2.52; 2.25 to 2.83) and moderately severe congenital heart defects (aOR: 6.25; 4.47 to 8.74). Girls had an overall decreased risk of 2+ admissions (aOR: 0.84; 0.78 to 0.91). Preterm birth was a significant risk factor for admissions in all anomaly subgroups but the effect of the other characteristics varied according to anomaly subgroup.

CONCLUSIONS

Over two-thirds of infants with an anomaly are admitted to hospital during infancy. Our findings identified sociodemographic and clinical characteristics contributing to an increased risk of hospitalisation of infants with congenital anomalies.

Increased Risk for Respiratory Complications in Male Extremely Preterm Infants: A Propensity Score Matching Study

BACKGROUND

Many factors can affect the clinical outcome of extremely premature infants (EPIs), but the effect of sex is paradoxical. This study used propensity score matching to adjust baseline information to reassess the clinical outcome of EPIs based on sex.

METHODS

A retrospective analysis was performed on EPIs admitted in the Department of Neonatology of the Third Affiliated Hospital of Guangzhou Medical University from 2011 to 2020. A propensity score matching (PSM) analysis was used to adjust the confounding factors including gestational age, birth weight, 1-minute Apgar score ≤ 3, withholding or withdrawing life-sustaining treatment(WWLST), mechanical ventilation, duration of mechanical ventilation, the mother with advanced age (≥35 years old), complete-course antenatal steroid therapy and hypertensive disorders of pregnancy. The survival rate at discharge and the incidence of major complications were evaluated between the male and female groups.

RESULTS

A total of 439 EPIs were included, and 240 (54.7%) infants were males. After matching the nine confounding factors, 148 pairs of infants were finally enrolled. There was no significant difference in the survival rate at discharge, as well as the mortality of activating treatment or WWLST between the two groups (all P>0.05). However, the incidence of respiratory distress syndrome, bronchopulmonary dysplasia (BPD), and moderate to severe BPD in the male group was significantly increased (all P<0.01), especially at birth weight between 750 and 999 grams.

CONCLUSIONS

The male EPIs have a higher risk of respiratory complications than females, particularly at 750 to 999 grams of birth weight.

Survival and decannulation across indications for infant tracheostomy: a twelve-year single-center cohort study

OBJECTIVE

Describe survival and decannulation following infant tracheostomy based on indication for tracheostomy placement.

STUDY DESIGN

Retrospective cohort study of infants who received tracheostomy at a single pediatric hospital over a twelve-year period. Primary and secondary indications were categorized into pulmonary, anatomic, cardiac, neurologic/musculoskeletal, and others.

RESULTS

A total of 378 infants underwent tracheostomy; 323 had sufficient data to be included in analyses of post-discharge outcomes. Overall mortality was 26.3%; post-operative and post-discharge mortality differed across primary indications (P = 0.03 and P = 0.005). Among survivors, 69.3% decannulated at a median age of 3.0 years (IQR 2.3, 4.5 years). Decannulation among survivors varied across primary indications (P = 0.002), ranging from 17% to 75%. In multivariable analysis, presence of a neurologic or musculoskeletal indication for tracheostomy was a significant negative predictor of future decannulation (aOR 0.10 [95% CI 0.02-0.44], P = 0.003).

CONCLUSIONS

Early childhood outcomes vary across indications for infant tracheostomy.

Associations between size at birth and size at 6 years among preterm infants: a retrospective cohort study

BACKGROUND

Little is known about the relationship between fetal growth and size at school age in children born prematurely. We evaluated the relationships between gestational age and anthropometric z-scores at birth and size at 6 years of age in very-low-birthweight infants born at <30 weeks' gestation.

METHODS

We collected data from the medical records of 187 preterm children at birth and 6 years of age. We evaluated correlations between gestational age and z-scores for weight, body length, and head circumference at birth and z-scores for weight, height, and body mass index at 6 years of age.

RESULTS

Simple regression analysis showed that, in boys and the overall group, gestational age and z-scores for weight, body length, and head circumference at birth had significant association with z-scores for weight, height, and body mass index at 6 years of age. No significant associations were found in girls, except for weight z-scores at 6 years with gestational age and head circumference z-scores at birth. Multiple regression analysis showed that gestational age and length z-score at birth were significantly and independently associated with weight and height z-score at 6 years. Gestational age was also significantly and independently associated with body mass index z-score at 6 years.

CONCLUSION

Gestational age and fetal growth in length (assessed with the birth-length z-score) were associated with anthropometric z-scores at 6 years in very-low-birthweight children born at <30 weeks of gestation, especially in boys.

Biochemical profile of human infant cerebrospinal fluid in intraventricular hemorrhage and post-hemorrhagic hydrocephalus of prematurity

Background

Intraventricular hemorrhage (IVH) and post-hemorrhagic hydrocephalus (PHH) have a complex pathophysiology involving inflammatory response, ventricular zone and cell–cell junction disruption, and choroid-plexus (ChP) hypersecretion. Increased cerebrospinal fluid (CSF) cytokines, extracellular matrix proteins, and blood metabolites have been noted in IVH/PHH, but osmolality and electrolyte disturbances have not been evaluated in human infants with these conditions. We hypothesized that CSF total protein, osmolality, electrolytes, and immune cells increase in PHH.

Methods

CSF samples were obtained from lumbar punctures of control infants and infants with IVH prior to the development of PHH and any neurosurgical intervention. Osmolality, total protein, and electrolytes were measured in 52 infants (18 controls, 10 low grade (LG) IVH, 13 high grade (HG) IVH, and 11 PHH). Serum electrolyte concentrations, and CSF and serum cell counts within 1-day of clinical sampling were obtained from clinical charts. Frontal occipital horn ratio (FOR) was measured for estimating the degree of ventriculomegaly. Dunn or Tukey’s post-test ANOVA analysis were used for pair-wise comparisons.

Results

CSF osmolality, sodium, potassium, and chloride were elevated in PHH compared to control (p = 0.012 − < 0.0001), LGIVH (p = 0.023 − < 0.0001), and HGIVH (p = 0.015 − 0.0003), while magnesium and calcium levels were higher compared to control (p = 0.031) and LGIVH (p = 0.041). CSF total protein was higher in both HGIVH and PHH compared to control (p = 0.0009 and 0.0006 respectively) and LGIVH (p = 0.034 and 0.028 respectively). These differences were not reflected in serum electrolyte concentrations nor calculated osmolality across the groups. However, quantitatively, CSF sodium and chloride contributed 86% of CSF osmolality change between control and PHH; and CSF osmolality positively correlated with CSF sodium (r, p = 0.55,0.0015), potassium (r, p = 0.51,0.0041), chloride (r, p = 0.60,0.0004), but not total protein across the entire patient cohort. CSF total cells (p = 0.012), total nucleated cells (p = 0.0005), and percent monocyte (p = 0.016) were elevated in PHH compared to control. Serum white blood cell count increased in PHH compared to control (p = 0.042) but there were no differences in serum cell differential across groups. CSF total nucleated cells also positively correlated with CSF osmolality, sodium, potassium, and total protein (p = 0.025 − 0.0008) in the whole cohort.

Conclusions

CSF osmolality increased in PHH, largely driven by electrolyte changes rather than protein levels. However, serum electrolytes levels were unchanged across groups. CSF osmolality and electrolyte changes were correlated with CSF total nucleated cells which were also increased in PHH, further suggesting PHH is a neuro-inflammatory condition.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00295-8.

Global incidence of intraventricular hemorrhage among extremely preterm infants: a systematic literature review

OBJECTIVES

To conduct a systematic literature review to evaluate the global incidence of intraventricular hemorrhage grade 2-4 among extremely preterm infants.

METHODS

We performed searches in MEDLINE and Embase for intraventricular hemorrhage and prematurity cited in English language observational studies published from May 2006 to October 2017. Included studies analyzed data from infants born at ≤28 weeks' gestational age and reported on intraventricular hemorrhage epidemiology.

RESULTS

Ninety-eight eligible studies encompassed 39 articles from Europe, 31 from North America, 25 from Asia, five from Oceania, and none from Africa or South America; both Europe and North America were included in two publications. The reported global incidence range of intraventricular hemorrhage grade 3-4 was 5-52% (Europe: 5-52%; North America: 8-22%; Asia: 5-36%; Oceania: 8-13%). When only population-based studies were included, the incidence range of intraventricular hemorrhage grade 3-4 was 6-22%. The incidence range of intraventricular hemorrhage grade 2 was infrequently documented and ranged from 5-19% (including population-based studies). The incidence of intraventricular hemorrhage was generally inversely related to gestational age.

CONCLUSIONS

Intraventricular hemorrhage is a frequent complication of extremely preterm birth. Intraventricular hemorrhage incidence range varies by region, and the global incidence of intraventricular hemorrhage grade 2 is not well documented.

A study of sex difference in infant mortality in UK pediatric intensive care admissions over an 11-year period

Within the UK, child mortality from all causes has declined for all ages over the last three decades. However, distinct inequality remains, as child mortality rates are generally found to be higher in males. A significant proportion of childhood deaths in the UK occur in Paediatric Intensive Care Units (PICU). We studied the association of sex with infant mortality in PICUs. We included all infants (0 to 12 months old) admitted to UK PICUs from 01/01/2005 to 31/12/2015 using the Paediatric Intensive Care Audit Network (PICANet) dataset. We considered first admissions to PICU and fitted a cause-specific-hazard-ratio (CSHR) model, and a logistic model to estimate the adjusted association between sex and mortality in PICU. Pre-defined subgroups were children less than 56-days old, and those with a primary diagnosis of infection. Of 71,243 cases, 1,411/29,520 (4.8%) of females, and 1,809/41,723 (4.3%) of males died. The adjusted male/female CSHR was 0.87 (95%-CI 0.81 to 0.92) representing a 13% higher risk of death for females. The adjusted OR for male to female mortality is 0.86 (95%-CI 0.80 to 0.93). Analyses in subgroups yielded similar findings. In our analysis, female infants have a higher rate of PICU mortality compared to male infants.

Male Disadvantage in Oxidative Stress-Associated Complications of Prematurity: A Systematic Review, Meta-Analysis and Meta-Regression

A widely accepted concept is that boys are more susceptible than girls to oxidative stress-related complications of prematurity, including bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), and periventricular leukomalacia (PVL). We aimed to quantify the effect size of this male disadvantage by performing a systematic review and meta-analysis of cohort studies exploring the association between sex and complications of prematurity. Risk ratios (RRs) and 95% CIs were calculated by a random-effects model. Of 1365 potentially relevant studies, 41 met the inclusion criteria (625,680 infants). Male sex was associated with decreased risk of hypertensive disorders of pregnancy, fetal distress, and C-section, but increased risk of low Apgar score, intubation at birth, respiratory distress, surfactant use, pneumothorax, postnatal steroids, late onset sepsis, any NEC, NEC > stage 1 (RR 1.12, CI 1.06–1.18), any IVH, severe IVH (RR 1.28, CI 1.22–1.34), severe IVH or PVL, any BPD, moderate/severe BPD (RR 1.23, CI 1.18–1.27), severe ROP (RR 1.14, CI 1.07–1.22), and mortality (RR 1.23, CI 1.16–1.30). In conclusion, preterm boys have higher clinical instability and greater need for invasive interventions than preterm girls. This leads to a male disadvantage in mortality and short-term complications of prematurity.

Global prevalence of long-term neurodevelopmental impairment following extremely preterm birth: a systematic literature review

Objective

Neurodevelopmental impairment (NDI) is a major complication of extreme prematurity. This systematic review was conducted to summarize the worldwide long-term prevalence of NDI associated with extreme prematurity.

Methods

Embase and MEDLINE databases were searched for epidemiologic and observational/real-world studies, published in English between 2011 and 2016, reporting long-term prevalence of NDI (occurring from 1 year) among extremely preterm infants born at gestational age (GA) ≤28 weeks.

Results

Of 2406 articles identified through searches, 69 met the protocol NDI definition (24 North America, 25 Europe, 20 Rest of World). Prevalence of any severity NDI in North America was 8%–59% at 18 months to 2 years, and 11%–37% at 2–5 years; prevalence of moderate NDI in Europe was 10%–13% at 18 months to 2 years, 3% at 2–5 years, and 9%–19% at ≥5 years; prevalence of any NDI in Rest of World was 15%–61% at 18 months to 2 years, and 42% at 2–5 years (no North America/Rest of World studies reported any NDI at ≥5 years). A trend toward higher prevalence of NDI with lower GA at birth was observed.

Conclusions

Extreme prematurity has a significant long-term worldwide impact on neurodevelopmental outcomes.

Function and Biomarkers of the Blood-Brain Barrier in a Neonatal Germinal Matrix Haemorrhage Model

Germinal matrix haemorrhage (GMH), caused by rupturing blood vessels in the germinal matrix, is a prevalent driver of preterm brain injuries and death. Our group recently developed a model simulating GMH using intrastriatal injections of collagenase in 5-day-old rats, which corresponds to the brain development of human preterm infants. This study aimed to define changes to the blood-brain barrier (BBB) and to evaluate BBB proteins as biomarkers in this GMH model. Regional BBB functions were investigated using blood to brain ¹⁴C-sucrose uptake as well as using biotinylated BBB tracers. Blood plasma and cerebrospinal fluids were collected at various times after GMH and analysed with ELISA for OCLN and CLDN5. The immunoreactivity of BBB proteins was assessed in brain sections. Tracer experiments showed that GMH produced a defined region surrounding the hematoma where many vessels lost their integrity. This region expanded for at least 6 h following GMH, thereafter resolution of both hematoma and re-establishment of BBB function occurred. The sucrose experiment indicated that regions somewhat more distant to the hematoma also exhibited BBB dysfunction; however, BBB function was normalised within 5 days of GMH. This shows that GMH leads to a temporal dysfunction in the BBB that may be important in pathological processes as well as in connection to therapeutic interventions. We detected an increase of tight-junction proteins in both CSF and plasma after GMH making them potential biomarkers for GMH.

Extremely Low Birth Weight and Accelerated Biological Aging

BACKGROUND AND OBJECTIVES

Extremely low birth weight (ELBW) (<1000 g) survivors are exposed to elevated levels of physiologic stress during their lives and may be susceptible to accelerated aging. Using the oldest known longitudinally followed cohort of ELBW survivors, we compared biological aging in this group using an epigenetic clock to a sample of matched normal birth weight (NBW) (>2500 g) control participants.

METHODS

Buccal cells were collected from 45 ELBW survivors and 49 NBW control participants at 30 to 35 years of age. Epigenetic age was calculated from the weighted average of DNA methylation at 353 cytosine-phosphate-guanine sequence within DNA sites, by using the Illumina Infinium Human Methylation EPIC 850k BeadChip array.

RESULTS

Before and after statistically adjusting for neurosensory impairment and the presence of chronic health conditions, a significant sex by birth weight group interaction was observed in the 353-site epigenetic-clock assay (P = .03), whereby ELBW men had a significantly older epigenetic age than NBW men (4.6 years; P = .01). Women born at ELBW were not found to be epigenetically older than their NBW peers.

CONCLUSIONS

The results of this study suggest that prenatal exposures may play an important role in aging, and that men born preterm may experience accelerated aging relative to their peers. We further highlight the need to monitor and promote the health of preterm survivors, with a particular focus on healthy aging across the life span.

Predictors of persistent and changing developmental problems of preterm children

BACKGROUND

Accurate prediction of persistent and emerging developmental problems in preterm-born children may lead to targeted interventions.

AIMS

To determine whether specific perinatal and social factors were associated with persistent, emerging, and resolving developmental problems of early-preterm (EPs) and moderately-and-late-preterm children (MLPs) from before to after school entry.

STUDY DESIGN

Observational longitudinal cohort study, part of the LOLLIPOP cohort-study.

SUBJECTS

341 EPs and 565 MLPs.

OUTCOME MEASURES

Developmental problems using the Ages and Stages Questionnaire at ages 4 and 5. We collected data on perinatal and social factors from medical records. Using logistic regression analyses we assessed associations between 48 factors and persistent, emerging, and resolving problems.

RESULTS

Of EPs, 8.7% had persistent and 5.1% emerging problems; this was 4.3% and 1.9% for MLPs, respectively. Predictors for persistent problems included chronic mental illness of the mother, odds ratio (95% confidence interval) 8.01 (1.85-34.60), male sex 4.96 (2.28-10.82), being born small-for-gestational age (SGA) 2.39 (1.15-4.99), and multiparity 3.56 (1.87-6.76). Predictors for emerging problems included MLP birth with prolonged premature rupture of membranes (PPROM) 5.01 (1.38-18.14). Including all predictors in a single prediction model, the explained variance (Nagelkerke R²) was 21.9%, whereas this was 3.0% with only EP/MLP birth as predictor.

CONCLUSIONS

Only few perinatal and social factors had associations with persistent and emerging developmental problems for both EPs and MLPs. For children with specific neonatal conditions such as SGA, and PPROM in MLPs, problems may persist. Insight in risk factors largely improved the prediction of developmental problems among preterm children.

Children Born Prematurely May Demonstrate Catch-Up Growth in Pre-Adolescence

Introduction Children born prematurely often score lower on standardized tests of language in early childhood. Less is known about longer term outcomes. This investigation considered language outcomes in pre-adolescent children born very preterm/very low birthweight, as assessed by both standardized test scores and language sample measures, and explored attention abilities as a possible moderating factor. Method The present investigation provided a longitudinal follow-up to Mahurin Smith et al. (2014) by examining the language outcomes of 84 children at the 11-year time point (39 with a history of prematurity and 45 born at full term) and a total of 82 at the 12-year time point (37 with a history of prematurity, 45 born at full term). Assessments included subtests of the Clinical Evaluation of Language Fundamentals- Fourth Edition, productive language measures taken from narrative tasks, and parent and examiner ratings of attention. Results Gestational age significantly predicted standardized language scores at age 11 years, but this effect was no longer statistically significant at age 12 years. When parent ratings of attention were considered as additional variables, gestational age was no longer a significant predictor. Gestational age did not serve as a significant predictor for the productive language measures at either time point. Discussion Results indicate that catch-up growth in language may take place in pre-adolescence for many children born prematurely. Clinical implications focus on the need to utilize multiple forms of language assessment and to directly consider the potential role of attention on standard test results.

Use of impregnated catheters to decrease colonization rates in neonates - A randomized controlled pilot trial

OBJECTIVE

Nosocomial infections increase mortality and morbidity in preterm infants. Central venous line colonization is a major risk factor for the development of such infections. In adults and children, antibiotic and antimycotic impregnated catheters have been demonstrated to reduce colonization. However, recently published data showed no significant difference in bloodstream infection in neonates when an impregnated catheter was used. We investigated the effect of impregnation of percutaneously inserted micro-catheters (PICC) on colonization in preterm and sick term infants in our unit.

METHODS

Neonates were randomly assigned to receive either a standard (S-PICC; n = 34) or antibiotic and antimycotic impregnated (IP-PICC; n = 37) PICC. Catheters were placed and removed according to a standard procedure and subsequently examined by roll-out culture. The primary outcome was the rate of colonization defined as >15 colony-forming-units/ml. Additional outcomes were catheter associated or systemic infections.

RESULTS

The rate of colonization was lower in neonates who received an IP-PICC as compared to S-PICC (5.6% vs. 12.1% respectively; p = 0.42). However, the difference was not significant. In IP-PICC vs S-PICC, catheter related local infection (CRI) although lower was not statistically significant (2.9% vs. 6.1%; p = 0.60). We observed no difference in catheter related systemic infection (CR-SI) (0% vs. 3.1%, p = 0.48). The neonates whose catheters were colonized were predominantly of a lower gestational age (median 254/7, p = 0.05) and males (100%, p = 0.01). In addition, the median colony count in the colonized IP-PICC catheters was lower as compared to S- PICC group (53 vs 250, p = 0.06).

CONCLUSIONS

The use of antibiotic and antimycotic impregnated PICC-lines in neonates tended to decrease colonization rates in neonates in our centers but this difference was not significant. Lower gestational age and male sex are risk factors for catheter colonization.

Sex related difference in cardiac output during neonatal transition in term neonates

Background

The immediate transition from foetus to neonate includes substantial changes especially concerning the cardiovascular system. As sex related differences have been shown in cardiovascular medicine, this topic warrants further investigation in neonatology. Aim: The aim of this present study was to measure cardiac output (CO) and cerebral oxygenation (cTOI) non-invasively in term neonates and to investigate potential sex related differences between female and male neonates after birth.

Methods

This is a mono-centric prospective observational study. For CO-measurements, the electrical velocimetry method was used. The pulse oximetry for arterial oxygen saturation and heart-rate measurements was placed on the right hand or wrist. cTOI was measured using a NIRO 200NX monitor. The near-infrared spectroscopy probe was positioned on the right side of forehead in each infant. Monitoring started at minute 1 and was continued until minute 15 after birth. At minutes 5, 10, and 15 after birth, CO was calculated as an average out of six 10-second periods.

Results

99 term neonates were enrolled. In our study population, we could identify 54 female and 45 male neonates. Males had higher cardiac output compared to females throughout the observational period, with a significant difference in minute 15 after birth (217, 95% CI: 203-231 mL/kg/min versus 178, 95% CI: 163-192 mL/kg/min; P<0.001). cTOI, SpO₂, and HR did not differ between male and female neonates.

Conclusions

The present work is the first to investigate sex related differences concerning cardiac output in term neonates during postnatal transition, showing a significantly higher cardiac output in male neonates 15 minutes after birth.