Effects of birth order, gender, and intrauterine growth retardation on the outcome of very low birth weight in twins

Isoniazid preventive therapy during infancy does not adversely affect growth among HIV-exposed uninfected children: Secondary analysis of data from a randomized controlled trial

BACKGROUND

Isoniazid preventive therapy (IPT) decreases risk of tuberculosis (TB) disease; impact on long-term infant growth is unknown. In a recent randomized trial (RCT), we assessed IPT effects on infant growth without known TB exposure.

METHODS

The infant TB Infection Prevention Study (iTIPS) trial was a non-blinded RCT among HIV-exposed uninfected (HEU) infants in Kenya. Inclusion criteria included age 6-10 weeks, birthweight ≥2.5 kg, and gestation ≥37 weeks. Infants in the IPT arm received 10 mg/kg isoniazid daily for 12 months, while the control trial received no intervention; post-trial observational follow-up continued through 24 months of age. We used intent-to-treat linear mixed-effects models to compare growth rates (weight-for-age z-score [WAZ] and height-for-age z-score [HAZ]) between trial arms.

RESULTS

Among 298 infants, 150 were randomized to IPT, 47.6% were females, median birthweight was 3.4 kg (interquartile range [IQR] 3.0-3.7), and 98.3% were breastfed. During the 12-month intervention period and 12-month post-RCT follow-up, WAZ and HAZ declined significantly in all children, with more HAZ decline in male infants. There were no growth differences between trial arms, including in sex-stratified analyses. In longitudinal linear analysis, mean WAZ (β = 0.04 [95% CI:-0.14, 0.22]), HAZ (β = 0.14 [95% CI:-0.06, 0.34]), and WHZ [β = -0.07 [95% CI:-0.26, 0.11]) z-scores were similar between arms as were WAZ and HAZ growth trajectories. Infants randomized to IPT had higher monthly WHZ increase (β to 24 months 0.02 [95% CI:0.01, 0.04]) than the no-IPT arm.

CONCLUSION

IPT administered to HEU infants did not significantly impact growth outcomes in the first two years of life.

Maternal Underweight and Its Association with Composite Index of Anthropometric Failure among Children under Two Years of Age with Diarrhea in Bangladesh

Malnutrition in women has been a long-standing public health concern, with serious effects on child survival and development. Maternal body mass index (BMI) is an important maternal nutritional indicator. There are few published studies although child anthropometric failures do not occur in isolation and identifying children with single versus several co-occurring failures can better capture cases of growth failure in combination: stunting, wasting, and underweight. In the context of multiple anthropometric failures, traditional markers used to assess children's nutritional status tend to underestimate overall undernutrition. Using the composite index of anthropometric failure (CIAF), we aimed to assess the association between maternal undernutrition and child undernutrition among children with diarrhea under the age of two and to investigate the correlates. Using 1431 mother-child dyads from the Antibiotic for Children with Diarrhea (ABCD) trial, we extracted children's data at enrollment and on day 90 and day 180 follow-ups. ABCD was a randomized, multi-country, multi-site, double-blind, placebo-controlled clinical trial. The Bangladesh site collected data from July 2017 to July 2019. The outcome variable, CIAF, allows combinations of height-for-age, height-for-weight, and weight-for-age to determine the overall prevalence of undernutrition. The generalized estimating equation was used to explore the correlates of CIAF. After adjusting all the potential covariates, maternal undernutrition status was found to be strongly associated with child undernutrition using the CIAF [aOR: 1.4 (95% CI: 1.0, 1.9), p-value = 0.043] among the children with diarrhea under 2 years old. Maternal higher education had a protective effect on CIAF [aOR: 0.7 (95% CI: 0.5, 0.9), p-value = 0.033]. Our study findings highlight the importance of an integrated approach focusing on maternal nutrition and maternal education could affect a reduction in child undernutrition based on CIAF.

Concurrence of stunting and overweight/obesity among children: Evidence from Ethiopia

Background

Nutrition transition in many low- and middle-income countries (LMICs) has led to shift in childhood nutritional outcomes from a predominance of undernutrition to a double burden of under- and overnutrition. Yet, policies that address undernutrition often times do not include overnutrition nor do policies on overweight, obesity reflect the challenges of undernutrition. It is therefore crucial to assess the prevalence and determinants of concurrence stunting and overweight/obesity to better inform nutrition programs in Ethiopia and beyond.

Methods

We analyzed anthropometric, sociodemographic and dietary data of children under five years of age from 2016 Ethiopian Demographic and Health Survey (EDHS). A total of 8,714 children were included in the current study. Concurrence of stunting and overweight/obesity (CSO) prevalence was estimated by basic, underlying and immediate factors. To identify factors associated with CSO, we conducted hierarchical logistic regression analyses.

Results

The overall prevalence of CSO was 1.99% (95% CI, 1.57–2.53). The odds of CSO was significantly higher in children in agrarian region compared to their counter parts in the pastoralist region (AOR = 1.51). Other significant factors included; not having improved toilet facility (AOR = 1.94), being younger than 12 months (AOR = 4.22), not having history of infection (AOR = 1.83) and not having taken deworming tablet within the previous six months (AOR = 1.49).

Conclusion

Our study provided evidence on the co-existence of stunting and overweight/obesity among infants and young children in Ethiopia. Therefore, identifying children at risk of growth flattering and excess weight gain provides nutrition policies and programs in Ethiopia and beyond with an opportunity of earlier interventions through improving sanitation, dietary quality by targeting children under five years of age and those living in Agrarian regions of Ethiopia.

Sibling sex, but not androgens, shapes phenotypes in perinatal common marmosets (Callithrix jacchus)

When offspring share a womb, interactions among fetuses can impart lasting impressions on phenotypic outcomes. Such intrauterine interactions often are mediated by sex steroids (estrogens and androgens) produced by the developing fetuses. In many mammals, intrauterine interactions between brothers and sisters lead to masculinization of females, which can induce fitness consequences. Many litter-bearing primates, though, seem to escape androgen-mediated litter effects, begging why? Here, we investigated how the sex composition (i.e., same- or mixed-sex) of litters influences perinatal outcomes in the common marmoset monkey (Callithrix jacchus), using a combination of physiological, morphological, and behavioural assays. We hypothesized that androgens from male fetuses would mediate developmental differences across litter types. We found that newborns (24-36 hours old) from same- and mixed-sex litters were indistinguishable by urinary androgen profiles, birth weights, morphometrics, and behaviour. However, monkeys born into same- and mixed-sex litters exhibited subtle morphological and neurobehavioral differences later in the perinatal period, independent of their androgen profiles. Our findings suggest that while androgens from male fetuses likely do not organize their siblings' phenotypes, perinatal stimuli may initiate divergent developmental trajectories among siblings, which, in turn, promotes inter-individual variability within families.

Maternal depression does not affect complementary feeding indicators or stunting status of young children (6-23 months) in Northern Ghana

OBJECTIVE

Maternal depression may affect child feeding practice which is an important determinant of child nutritional status. The objective of this study was to explore the association between maternal depression and WHO complementary feeding indicators [minimum dietary diversity (MDD), minimum meal frequency (MMF) and minimum acceptable diet (MAD)] or stunting status of children (6-23 months) in Tamale Metropolis, Ghana. A community-based cross-sectional study was carried out involving 200 mother-child pairs randomly sampled from three communities in Tamale Metropolis, Ghana.

RESULTS

The prevalence of MDD, MMF, and MAD were 56.5, 65.0, and 44.0% respectively and 41.0% of the children sampled were stunted. A third of the mothers (33.5%) screened positive for depression. Maternal depression did not influence significantly MDD (p = 0.245), MMF (p = 0.442), and MAD (p = 0.885) or children's risk of stunting (p = 0.872). In conclusion maternal depression and child stunting are prevalent in Northern Ghana but there is a lack of evidence of an association between maternal depression and child feeding practices or nutritional status in this study population. Further research is needed to assess the effect of maternal depression on feeding practices and growth of young children.

Risk factors of stunting among children living in an urban slum of Bangladesh: findings of a prospective cohort study

BACKGROUND

Bangladesh is one of the 20 countries with highest burden of stunting globally. A large portion (around 2.2 million) of the population dwells in the slum areas under severe vulnerable conditions. Children residing in the slums are disproportionately affected with higher burden of undernutrition particularly stunting. In this paper, findings of a prospective cohort study which is part of a larger multi-country study are presented.

METHODS

Two hundred and sixty five children were enrolled and followed since their birth till 24 months of age. Anthropometric measurements, dietary intake and morbidity information were collected monthly. Data from 9 to 12, 15-18 and 21-24 months were collated to analyze and report findings for 12, 18 and 24 months of age. Generalized estimating equation models were constructed to determine risk factors of stunting between 12 and 24 months of age.

RESULT

Approximately, 18% of children were already stunted (LAZ < -2SD) at birth and the proportion increased to 48% at 24 months of age. Exclusive breastfeeding prevalence was only 9.4% following the WHO definition at 6 months. Dietary energy intake as well as intakes of carbohydrate, fat and protein were suboptimal for majority of the children. However, in regression analysis, LAZ at birth (AOR = 0.40, 95% CI: 0.26, 0.61), household with poor asset index (AOR = 2.81, 95% CI: 1.43, 5.52; ref.: average asset index), being male children (AOR = 1.75, 95% CI: 1.04, 2.95; ref.: female) and age (AOR = 2.34, 95% CI: 1.56, 3.52 at 24 months, AOR = 2.13, 95% CI: 1.55, 2.92 at 18 months; ref.: 12 months of age) were the significant predictors of stunting among this population.

CONCLUSION

As the mechanism of stunting begins even before a child is born, strategies must be focused on life course approach and preventive measurement should be initiated during pregnancy. Alongside, government and policymakers have to develop sustainable strategies to improve various social and environmental factors those are closely interrelated with chronic undernutrition particularly concentrating on urban slum areas.

Surfactant phospholipid composition of gastric aspirate samples differs between male and female very preterm infants

BackgroundAmong preterm infants, males have a greater incidence of respiratory distress and death than do females born at the same gestational age, likely due to sex-related differences in lung maturation. Our aim was to determine whether surfactant phospholipid composition differs between male and female preterm infants.MethodsGastric aspirate samples from male and female infants born between 25 and 30 weeks of gestation at The Royal Women's Hospital, Melbourne, Australia, were collected within 1 h after birth. Phospholipid composition was analyzed by electrospray ionization tandem mass spectrometry.ResultsPreterm males had higher proportions of total phosphatidylinositol (PI) and phosphatidylserine 36:2, lower proportions of total sphingomyelin (S) and S 33:1 and 35:1, and a greater phosphatidylcholine (PC)/S ratio than did females. The proportions of PC 30:0, PC 34:0, PC 34:2, PC 36:2, PC 36:3, and PC 38:2 differed between the sexes at different gestational weeks of birth; the proportion of PC 32:0 (dipalmitoylphosphatidylcholine) in males was lower than that in females at 25 weeks of gestation but higher at 27 weeks.ConclusionPhospholipid composition in pulmonary surfactant is different between male and female preterm infants of the same gestational age, which may contribute to the increased risk for respiratory morbidities in one sex.

Early-life mortality risks in opposite-sex and same-sex twins: a Danish cohort study of the twin testosterone transfer hypothesis

PURPOSE

To investigate the twin testosterone transfer (TTT) hypothesis by comparing early-life mortality risks of opposite-sex (OS) and same-sex (SS) twins during the first 15 years of life.

METHODS

We performed a population-based cohort study to compare mortality in OS and SS twins. We included 68,629 live-born Danish twins from 1973 to 2009 identified through the Danish Twin Registry and performed piecewise stratified Cox regression and log-binomial regression.

RESULTS

Among 1933 deaths, we found significantly higher mortality for twin boys than for twin girls. For both sexes, OS twins had lower mortality than SS twins; the difference persisted for the first year of life for boys and for the first week of life for girls.

CONCLUSIONS

Although the mortality risk for OS boys was in the expected direction according to the TTT hypothesis, the results for OS girls pointed in the opposite direction, providing no clear evidence for the TTT hypothesis.

Dysregulation of 11beta-hydroxysteroid dehydrogenases: implications during pregnancy and beyond

Glucococorticoids play a critical role in the developmental programing and fetal growth. Key molecules mediating and regulating tissue-specific glucocorticoid actions are 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 and 2 isozymes, both of which are expressed in the placenta and the fetal membranes. 11beta-HSD1 is implicated in the pathogenesis of metabolic syndrome and its dysregulation has been observed in pregnancy-related complications (pre-eclampsia, intrauterine growth restriction). Interestingly, preliminary clinical data have associated certain 11beta-HSD1 gene polymorphisms with hypertensive disorders in pregnancy, suggesting, if confirmed by further targeted studies, it's potential as a putative prognostic marker. Animal studies and observations in humans have confirmed that 11beta-HSD2 insufficiency is related with pregnancy adversity (pre-eclampsia, intrauterine growth restriction, preterm birth). Importantly, down-regulation or deficiency of placental 11beta-HSD2 is associated with significant restriction in fetal growth and low-birth weight, and unfavorable cardio-metabolic profile in adulthood. The potential association of 11beta-HSD1 tissue-specific dysregulation with gestational diabetes, as well as the plausible utility of 11beta-HSD2, as a biomarker of pregnancy adversity and later life morbidity, are emerging areas of intense scientific interest and future investigation.

Reappraisal of twinning: epidemiology and outcome in the early neonatal period

INTRODUCTION

The present study aimed to determine the epidemiology, maternal complications and adverse neonatal outcomes associated with twin births at a tertiary care hospital in India.

METHODS

A prospective observational study was conducted on all successively born twin pairs (≥ 23 weeks of gestation) and their mothers from January to September 2005. Main outcome measures included maternal medical/obstetric complications, labour characteristics and the morbidities/mortality observed during the early neonatal period.

RESULTS

The twinning rate was 1 in 54 deliveries. Around 10% of mothers had a predisposition for twinning in the form of familial tendency or consumption of clomiphene. Anaemia (85%) was the most common maternal complication, followed by gestational hypertension (17%). Nearly one-third of births were delivered via Caesarean section. Prematurity (61%) was the most common neonatal complication followed by early-onset neonatal sepsis (21%). The risk of early neonatal death was 27%. Shorter gestation and low birth weight were significantly associated with adverse neonatal outcome (p < 0.05). Factors such as chorionicity, mode of delivery, birth order, inter-twin delivery time interval, gender and intra-pair birth weight discordance did not affect neonatal morbidity or mortality (p ≥ 0.05).

CONCLUSION

The rates of maternal complications and early neonatal morbidities/mortality were quite high in twin gestations. Except for the prematurity and low birth weight, none of the other factors, including inter-twin delivery time interval of more than 15 mins, were found to affect neonatal outcome.

Intrauterine growth restriction transiently delays alveolar formation and disrupts retinoic acid receptor expression in the lung of female rat pups

BACKGROUND

We showed that intrauterine growth restriction (IUGR) increases distal airspace wall thickness at birth (postnatal age 0; P0) in rat pups (saccular stage of lung development). However, that report did not assess whether the saccular phenotype persisted postnatally or occurred in males or females, nor did the report identify a potential molecular pathway for the saccular phenotype at P0. We hypothesized that IUGR persistently delays alveolar formation and disrupts retinoic acid receptor (RAR) mRNA and protein levels in the lung of rat pups in a postnatal age- and sex-specific manner.

METHODS

IUGR was induced in pregnant rats by bilateral uterine artery ligation. Alveolar formation and expression of RARα, -β, and -γ were quantified at P0, P6 (alveolar stage), and P21 (postalveolarization).

RESULTS

IUGR increased distal airspace wall thickness in female pups at P0 only. IUGR did not affect male pups at any age. IUGR transiently increased lung RAR-β protein abundance, which inhibits alveolar formation, at P0 in female pups. Serum retinol concentration was normal at all ages.

CONCLUSION

IUGR alone is not sufficient to persistently delay postnatal alveolar formation or disrupt expression of RARs. We speculate that for IUGR to delay alveolar formation postnatally, a second insult is necessary.

Individual and contextual factors associated with childhood stunting in Nigeria: a multilevel analysis

Stunting, a form of undernutrition, is the best measure of child health inequalities as it captures multiple dimensions of children's health, development and the environment where they live. The aim of this study was to quantify the predictors of childhood stunting in Nigeria. This study used data obtained from the 2008 Nigeria Demographic and Health Survey (NDHS). A total of 28 647 children aged 0-59 months included in NDHS in 2008 were analysed in this study. We applied multilevel multivariate logistic regression analysis in which individual-level factors were at the first level and community-level factors at the second level. The percentage change in variance of the full model accounted for about 46% in odds of stunting across the communities. The present study found that the following predictors increased the odds of childhood stunting: male gender, age above 11 months, multiple birth, low birthweight, low maternal education, low maternal body mass index, poor maternal health-seeking behaviour, poor household wealth and short birth interval. The community-level predictors found to have significant association with childhood stunting were: child residing in community with high illiteracy rate and North West and North East regions of the country. In conclusion, this study revealed that both individual- and community-level factors are significant determinants of childhood stunting in Nigeria.

Birthweight Discordance in Twins and the Risk of Being Heavier for Respiratory Distress Syndrome

Twin pregnancies are becoming common as a result of increased assisted reproduction. Studies have shown that the smaller twin of a pair is at greater risk of morbidity and mortality. Our aim was to determine if there is a relation between birth-weight discordancy and neonatal morbidity and mortality and to test the occurrence of respiratory distress syndrome (RDS) in discordant twins. For 5 years all twins admitted to our intensive care unit were included in the study. Discordance was calculated as the difference between twins' weights divided by the heavier weight. Diagnosis of RDS was made by typical clinical and radiographic methods. Multiple logistic regression was performed with gender, weight order and birth order as the independent variables and RDS as the dependent variable. Two hundred and sixty-six twin pairs with a mean gestation of 33 weeks and a mean birthweight of 1890 g were evaluated. Multiple logistic regression revealed that being the heavier twin was a more important risk factor for RDS (odds ratio 4.5; 95% confidence interval 2.2–9.2) than being the male or second-born twin. Based on neonatal outcomes a birthweight discordance equal or greater than 20% in twin pairs was accepted as the discordance criterion. Discordant and concordant groups were statistically different in neonatal mortality, necrotizing enterocolitis, polycytemia and hypoglycemia. Our data demonstrated that being the heavier twin is a risk factor for RDS and a birth-weight difference of 20% or more in twin pairs should be accepted as discordance.

The guinea pig as an animal model for studying perinatal changes in microvascular function

INTRODUCTION

Microvascular dysfunction, characterized by inappropriate vasodilatation and high blood flow in the peripheral microcirculation, is linked to physiologic instability and poor outcome in neonates. Specifically, preterm neonates have significantly higher levels of baseline microvascular blood flow than term neonates at 24 h postnatal age. Because of similarities between human and guinea pig endocrine profiles and maturity at birth, we hypothesized that preterm guinea pig neonates would provide a suitable model for studying the mechanisms underlying transitional microvascular function.

RESULTS

Guinea pigs that were delivered preterm showed immaturity and had markedly reduced viability. Baseline microvascular blood flow was significantly higher in preterm animals than in term animals. No effect of intrauterine growth restriction or birth weight on baseline microvascular blood flow was observed in either preterm or term animals.

DISCUSSION

These results are consistent with recent clinical findings and support the use of the guinea pig as a suitable model for future studies of the mechanisms underlying perinatal microvascular behavior.

METHODS

Guinea pigs were delivered either prematurely or at term. Laser Doppler flowmetry was used to study microvascular blood flow at 23 h postnatal age.

Epigenetics and the developmental origins of lung disease

The developmental origins of disease hypothesis have recently been expanded to include the early origins of lung disease, particularly early events that alter lung development. Intrauterine growth restriction (IUGR), preterm birth with the need for prolonged mechanical ventilation, and maternal tobacco smoke (MTS) or nicotine exposure produce neonatal and adult lung disease. These perinatal insults are characterized by alterations in alveolar formation and changes in the expression of genes that regulate alveolarization, including IGF1 and PPARγ. A potential mechanism for such changes in gene expression is epigenetics. IGF1 and PPARγ have altered epigenetic states in response to these perinatal insults. Identification of the specific epigenetic mechanisms involved in the developmental origin of lung disease may facilitate identification of molecular biomarkers with the potential to personalize respiratory disease risk assessment and treatment. The purpose of this review is to summarize what is known about the developmental origins of lung disease, the epigenetic contributions to lung disease, and areas that need further investigation.

Neonatal functional lung maturity relative to gestational age at delivery, fetal growth, and pregnancy characteristics in triplet births

OBJECTIVE

The purpose of this study was to determine if functional lung maturity (FtLM) of triplets was affected by differentiating factors within the triplet set.

METHODS

This was a retrospective cohort study of triplets. Data were collected on maternal, pregnancy and neonatal characteristics and FtLM was determined, based on selected neonatal outcomes.

RESULTS

Functional lung immaturity (FtLI) was found in 35.5% of the infants and occurred in those born between 28.1 and 34.6 weeks gestation. Gestational age at delivery, pre-pregnancy BMI, and gestational diabetes were predictive of an infant having FtLM; while infertility treatment, pre-pregnancy BMI, and preeclampsia were predictors of FtLM discordance.

CONCLUSIONS

Our results demonstrated FtLI was likely at early gestation (<28 weeks) and FtLM was probable beyond 35 weeks. Discordance for FtLM was likely at 32 weeks; therefore, clinicians should guard against complacency that this gestational mark assures an uncomplicated respiratory course for all infants within the set.

Male gender is associated with intraventricular hemorrhage

OBJECTIVE

The goal was to examine the association of gender with intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL) in a large national database.

METHODS

The National Inpatient Sample database was analyzed for the years 1998, 1999, 2001, 2002, and 2004 and its pediatrics version for the years 1997, 2000, and 2003. The National Inpatient Sample and its pediatrics version are annually collected databases for inpatient admissions from >1000 hospitals across the United States. We included all very low birth weight (VLBW) infants (birth weight [BW] of <1500 g) and excluded infants with major congenital anomalies. VLBW infants with IVH or PVL were identified by using International Classification of Diseases, Ninth Revision, diagnostic codes. We analyzed the data by using chi(2) and Fisher's exact tests to calculate odds ratios (ORs) and logistic regression analysis to control for possible confounders.

RESULTS

The data included 104 847 VLBW infants. With controlling for significant confounders, IVH was associated with male gender (15.9% vs 13.6%; adjusted OR [AOR]: 1.15 [95% confidence interval: 1.11-1.19]; P < .001). More boys than girls had severe IVH (38% vs 32.7%; AOR: 1.18 [95% confidence interval: 1.06-1.32]; P < .004). The increased rates of IVH and severe IVH in boys were significant in the BW subgroups of <1000 g and 1000 to 1499 g. The association of male gender with IVH and severe IVH was more significant in infants of 1000 to 1499 g (AOR: 1.19 vs 1.14; P = .006). The incidence of PVL in VLBW infants was 0.41%, and rates did not differ between genders (0.38% vs 0.43%; P = .42).

CONCLUSIONS

Compared with girls, VLBW male newborns are at greater risk to develop IVH and severe IVH but not PVL. The association of male gender with IVH or severe IVH is stronger with higher BWs.

Maternal exposure to floricultural work during pregnancy, PON1 Q192R polymorphisms and the risk of low birth weight

BACKGROUND

Although there is evidence from animal studies of impaired reproductive function by exposure to organophosphates (OP), the effects on birth weight have not been sufficiently evaluated in epidemiological studies. Paraoxonase (PON1) detoxifies organophosphates by cleavage of active oxons. Some PON1 gene polymorphisms could reduce the enzyme activity and increase susceptibility to OP toxicity.

OBJECTIVE

To assess the association between maternal exposure to floriculture during pregnancy and the risk of low birth weight (<2500 g) in their offspring, as well as to evaluate the interaction between this exposure and maternal genotype for PON1 Q192R polymorphisms.

MATERIALS AND METHODS

A cross sectional study was carried out in two Mexican states (States of Mexico and Morelos) with high frequencies of greenhouse activity. We interviewed and collected blood samples from 264 females (floriculturists or partners of floricultural workers) who became pregnant during the 10 years prior to the interview. The questionnaire measured socioeconomic characteristics, tobacco and alcohol consumption, diseases and occupational and reproductive history. We also applied a food frequency questionnaire. Information was obtained pertaining to 467 pregnancies. DNA was extracted from white cells, and PON1 genotype was determined by Restriction Fragment Length Polymorphism for Q192R polymorphisms. Results were analyzed with generalized estimating equations models.

RESULTS

After adjusting for potential confounders, we detected a statistically significant interaction between maternal exposure to flower growing work during pregnancy and PON1 Q192R polymorphisms on risk of low birth weight. The risk of having a baby with LBW is nearly six times higher if a mother is a floriculture worker during pregnancy and has PON1 192RR genotype (OR 5.93, 95% CI 1.28, 27.5).

CONCLUSION

These results suggest that the interaction between maternal floriculture work during pregnancy and 192RR PON1 genotype increases the probability of having children with LBW.

Neonatal brain structure on MRI and diffusion tensor imaging, sex, and neurodevelopment in very-low-birthweight preterm children

The neurological basis of an increased incidence of cerebral palsy (CP) in preterm males is unknown. This study examined neonatal brain structure on magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) at term-equivalent age, sex, and neurodevelopment at 1 year 6 months on the basis of the Amiel-Tison neurological examination, Gross Motor Function Classification System, and Bayley Scales of Infant Development in 78 very-low-birthweight preterm children (41 males, 37 females; mean gestational age 27.6 wks, SD 2.5; mean birthweight 1021 g, SD 339). Brain abnormalities on MRI and DTI were not different between males and females except in the splenium of the corpus callosum, where males had lower DTI fractional anisotropy (p=0.025) and a higher apparent diffusion coefficient (p=0.013), indicating delayed splenium development. In the 26 infants who were at higher risk on the basis of DTI, males had more abnormalities on MRI (p=0.034) and had lower fractional anisotropy and a higher apparent diffusion coefficient in the splenium (p=0.049; p=0.025) and right posterior limb of the internal capsule (PLIC; p=0.003; p=0.033). Abnormal neurodevelopment was more common in males (n=9) than in females (n=2; p=0.036). Children with abnormal neurodevelopment had more abnormalities on MRI (p=0.014) and reduced splenium and right PLIC fractional anisotropy (p=0.001; p=0.035). In children with abnormal neurodevelopment, right PLIC fractional anisotropy was lower than left (p=0.035), whereas in those with normal neurodevelopment right PLIC fractional anisotropy was higher than left (p=0.001). Right PLIC fractional anisotropy correlated to neurodevelopment (rho=0.371, p=0.002). Logistic regression predicted neurodevelopment with 94% accuracy; only right PLIC fractional anisotropy was a significant logistic coefficient. Results indicate that the higher incidence of abnormal neurodevelopment in preterm males relates to greater incidence and severity of brain abnormalities, including reduced PLIC and splenium development.

The developmental origins of adult disease

PURPOSE OF REVIEW

Intrauterine growth restriction (IUGR) is associated with an increased propensity to develop adult-onset disease and is described by the developmental origins of adult disease hypothesis. Sequelae of fetal growth restriction include metabolic disease as well as nonmetabolic disorders. Although it has become clear that the morbidities associated with IUGR are complex and result from disruptions to multiple pathways and multiple organs, the mechanisms driving the long-term effects are only just beginning to be understood.

RECENT FINDINGS

IUGR affects most organ systems by either interrupting developmental processes such as apoptosis or producing lasting changes to levels of key regulatory factors. Both of these are associated with an often persistent change in gene expression. Epigenetic modulation of transcription is a mechanism that is at least partially responsible for this. IUGR is accompanied by changes in the quantity and activity of enzymes responsible for making modifications to chromatin as well as global and gene-specific modifications of chromatin.

SUMMARY

The subtle adjustments needed to ensure developmental plasticity in IUGR are provided by epigenetic modulation of critical genes. Translating the messages of the epigenetic profile and identifying the players that mediate the effects remains one of the major challenges in the field. An understanding of the mechanisms driving the epigenetic changes will facilitate identification of dietary and pharmaceutical approaches that can be applied in the postnatal period.

Verbal short-term memory span in children: long-term modality dependent effects of intrauterine growth restriction

BACKGROUND

Recent reports showed that children born with intrauterine growth restriction (IUGR) are at greater risk of experiencing verbal short-term memory span (STM) deficits that may impede their learning capacities at school. It is still unknown whether these deficits are modality dependent.

METHODS

This long-term, prospective design study examined modality-dependent verbal STM functions in children who were diagnosed at birth with IUGR (n = 138) and a control group (n = 64). Their STM skills were evaluated individually at 9 years of age with four conditions of the Visual-Aural Digit Span Test (VADS; Koppitz, 1981): auditory-oral, auditory-written, visuospatial-oral and visuospatial-written. Cognitive competence was evaluated with the short form of the Wechsler Intelligence Scales for Children--revised (WISC-R95; Wechsler, 1998).

RESULTS

We found IUGR-related specific auditory-oral STM deficits (p < .036) in conjunction with two double dissociations: an auditory-visuospatial (p < .014) and an input-output processing distinction (p < .014). Cognitive competence had a significant effect on all four conditions; however, the effect of IUGR on the auditory-oral condition was not overridden by the effect of intelligence quotient (IQ).

CONCLUSIONS

Intrauterine growth restriction affects global competence and inter-modality processing, as well as distinct auditory input processing related to verbal STM functions. The findings support a long-term relationship between prenatal aberrant head growth and auditory verbal STM deficits by the end of the first decade of life. Empirical, clinical and educational implications are presented.

Sex Ratios: Human Twins and Fraternal Effects

Historical data from Finnish populations reveals that, for females, exposure to a male twin in the womb may have significant, life-long, effects on subsequent fitness, with profound implications for the evolution of sex ratios and brood size.

Does fetal sex affect pregnancy outcome?

BACKGROUND

In maternal fetal medicine, gender differences in outcome are often observed.

OBJECTIVE

This article reviews the fetal sex-dependent differences found in many aspects of pregnancy, from conception through birth.

METHODS

The MEDLINE, EMBASE, and Current Contents databases were searched, for the years 1985 to 2006, using the following Medical Subject Headings and text words: fetal gender, finale, female, sex ratio at birth, pregnancy outcome, preterm birth, and stillbirth. The search was not limited by language. In addition, the bibliographies of known relevant articles were examined to capture any reports not already identified in the electronic search. All reports that provided information on gender differences in pregnancy outcome were included for review.

RESULTS

An extremely high male-to-female ratio was found in fetuses born after very short-duration pregnancy; this level declined around the 20th week and stabilized at term. In the absence of manipulation, both the sex ratio at birth and the population sex ratio have been found to remain consistent. A higher incidence of preterm birth and premature preterm rupture of membranes has been observed in different populations among mothers of male newborns compared with mothers of females. It has been speculated that this higher incidence may be linked to the relatively greater weight at lower gestational age of male newborns versus females. Women carrying male fetuses had higher rates of gestational diabetes mellitus, fetal macrosomia, failure to progress during the first and second stages of labor, cord prolapse, nuchal cord, and true umbilical cord knots. Cesarean sections were also more frequently found among male neonates compared with females.

CONCLUSIONS

Male sex is an independent risk factor for adverse pregnancy outcome. Evidence suggests that females have an advantage over males, with a better outcome in the perinatal period, particularly after preterm birth.

Boys are more stunted than girls in sub-Saharan Africa: a meta-analysis of 16 demographic and health surveys

Background

Many studies in sub-Saharan Africa have occasionally reported a higher prevalence of stunting in male children compared to female children. This study examined whether there are systematic sex differences in stunting rates in children under-five years of age, and how the sex differences in stunting rates vary with household socio-economic status.

Methods

Data from the most recent 16 demographic and health surveys (DHS) in 10 sub-Saharan countries were analysed. Two separate variables for household socio-economic status (SES) were created for each country based on asset ownership and mothers' education. Quintiles of SES were constructed using principal component analysis. Sex differentials with stunting were assessed using Student's t-test, chi square test and binary logistic regressions.

Results

The prevalence and the mean z-scores of stunting were consistently lower amongst females than amongst males in all studies, with differences statistically significant in 11 and 12, respectively, out of the 16 studies. The pooled estimates for mean z-scores were -1.59 for boys and -1.46 for girls with the difference statistically significant (p < 0.001). The stunting prevalence was also higher in boys (40%) than in girls (36%) in pooled data analysis; crude odds ratio 1.16 (95% CI 1.12–1.20); child age and individual survey adjusted odds ratio 1.18 (95% CI 1.14–1.22). Male children in households of the poorest 40% were more likely to be stunted compared to females in the same group, but the pattern was not consistent in all studies, and evaluation of the SES/sex interaction term in relation to stunting was not significant for the surveys.

Conclusion

In sub-Saharan Africa, male children under five years of age are more likely to become stunted than females, which might suggest that boys are more vulnerable to health inequalities than their female counterparts in the same age groups. In several of the surveys, sex differences in stunting were more pronounced in the lowest SES groups.

The genetics of bronchopulmonary dysplasia

Over the last 15 years, neonatal morbidity and mortality has changed little for very low birth weight babies despite significant technological and therapeutic advances. Bronchopulmonary dysplasia (BPD) continues to be a major problem despite antenatal steroid use, surfactant replacement therapy, gentle noninvasive ventilation techniques, permissive hypercarbia, and judicious use of oxygen. Current evidence supports multiple contributing factors. Prematurity is the cardinal factor; others include pulmonary baro/volutrauma, hyperoxia, and inflammation. BPD is an end product of pulmonary inflammatory response and lung repair with impaired alveolarization and vascularization in response to lung injury. These sequences involve multiple morphoregulatory molecules, which have a range of activities largely determined by genetic variability. A clearer understanding of genetic susceptibility for BPD has recently emerged. Twin studies have shown that the BPD status of one twin, even after correcting for contributing factors, is a highly significant predictor of BPD in the second twin. After controlling for covariates, genetic factors account for 53% (P = 0.004, 95% CI = 16%-89%) of the variance in liability for BPD. Incremental improvements will likely depend on identification of these genetic components for targeting specific therapies.

Wheezing illness and re-hospitalization in the first two years of life after neonatal respiratory distress syndrome

OBJECTIVES

To determine the impact of respiratory distress syndrome (RDS) on wheezing illnesses and re-hospitalizations in children as old as 2 years of age.

STUDY DESIGN

We observed 2 geographically defined cohorts of children with RDS born after 26 weeks of gestation during 1990 to 1995 and 1996 to 1999 and gestationally paired control subjects. Recurrent wheezing illness and the re-hospitalizations caused by a respiratory condition were recorded.

RESULTS

In the first year of life, 47 of 224 infants with RDS and 18 of 224 control subjects born in 1990 to 1995 had recurrent wheezing illness (P <.005) compared with 21 of 109 infants with RDS and 14 of 109 control subjects in the latter cohort (P=.27). A higher number of infants with RDS were readmitted to the hospital (25% versus 13%, P=.002) in the former period, and they spent more days in hospital during both periods. The frequencies of wheezing remained constant in the second year of life, but hospital admissions decreased. Siblings at home, male sex, and bronchopulmonary dysplasia were additional risk factors of wheezing illnesses.

CONCLUSION

RDS increases the incidence of wheezing illnesses during the first 2 years of life. Changes in the management of RDS during the 1990s was associated with a decreased incidence of subsequent RDS-associated respiratory morbidity.

Long-term outcomes in multiple gestations

Children born from a multiple gestation are at increased risk for cerebral palsy, learning disability, and language and neurobehavioral deficits. With the increased incidence of multiple pregnancies and use of assisted reproductive technology (ART), these issues are more commonly affecting parents. Long-term outcomes are a critical part of preconceptual and early pregnancy counseling for parents faced with a multiple gestation or considering ART, and the provider should be well versed on issues surrounding zygosity, gestational age, higher-order multiples, and the effects of options such as multifetal pregnancy reduction.

Exposure to ambient air pollution and prenatal and early childhood health effects

Over the last years, concern for the possible influence of exposure to air pollutants in children during gestation or the first years of life has grown; exposure levels which may be reached nowadays in our dwellings and in our streets. In the present study evidence over the possible impact of ambient air pollution on the foetus and the infants (i.e.: less than 1 year) published during the last decade, 1994--2003, are revised. Studies on infant mortality and exposure to particles show an outstanding consistence in the magnitude of the effects, despite the different designs used. As a whole, data show that an increase in 10 microg/m3 of particle concentration (measured as PM10) is associated with to about 5% increase in post-neonatal mortality for all causes and around 22% for post-neonatal mortality for respiratory diseases. Regarding damage in foetal health, although results are not always consistent, most studies show associations with exposure to air pollution during pregnancy. However, the precise mechanisms of action of air pollutants on adverse reproductive results are still unknown, so is the period of exposure most relevant during pregnancy and the specific pollutant which may represent a higher risk. Follow-up studies evaluating personal exposure to different air pollutants are required, allowing for the adequate evaluation of the impact of each pollutant in different periods of pregnancy, as well as providing hypotheses on their possible mechanisms of action.

Susceptibility to neoplastic and non-neoplastic pulmonary diseases in mice: genetic similarities

Chronic inflammation predisposes toward many types of cancer. Chronic bronchitis and asthma, for example, heighten the risk of lung cancer. Exactly which inflammatory mediators (e.g., oxidant species and growth factors) and lung wound repair processes (e.g., proangiogenic factors) enhance pulmonary neoplastic development is not clear. One approach to uncover the most relevant biochemical and physiological pathways is to identify genes underlying susceptibilities to inflammation and to cancer development at the same anatomic site. Mice develop lung adenocarcinomas similar in histology, molecular characteristics, and histogenesis to this most common human lung cancer subtype. Over two dozen loci, called Pas or pulmonary adenoma susceptibility, Par or pulmonary adenoma resistance, and Sluc or susceptibility to lung cancer genes, regulate differential lung tumor susceptibility among inbred mouse strains as assigned by QTL (quantitative trait locus) mapping. Chromosomal sites that determine responsiveness to proinflammatory pneumotoxicants such as ozone (O3), particulates, and hyperoxia have also been mapped in mice. For example, susceptibility QTLs have been identified on chromosomes 17 and 11 for O3-induced inflammation (Inf1, Inf2), O3-induced acute lung injury (Aliq3, Aliq1), and sulfate-associated particulates. Sites within the human and mouse genomes for asthma and COPD phenotypes have also been delineated. It is of great interest that several susceptibility loci for mouse lung neoplasia also contain susceptibility genes for toxicant-induced lung injury and inflammation and are homologous to several human asthma loci. These QTLs are described herein, candidate genes are suggested within these sites, and experimental evidence that inflammation enhances lung tumor development is provided.

Neonatal management of the growth-restricted infant

Close collaboration between obstetricians and neonatologists is essential for proper care of the growth-restricted fetus. A joint decision on the appropriate timing of delivery is made, based on the risk of fetal compromise compared with that of neonatal morbidity. A neonatal resuscitative team should be available at delivery. Gestational assessment, anthropological measurements and physical examination are necessary to confirm the diagnosis of intra-uterine growth retardation and establish the symmetric, asymmetric, combined or dysmorphic classification. Neonatal management requires special attention to a number of significant morbidities that growth-restricted infants are more prone to develop compared with normally grown infants, including asphyxia, meconium aspiration syndrome, respiratory distress syndrome, massive pulmonary haemorrhage, chronic lung disease, hypothermia, hypoglycaemia, hypocalcaemia, polycythaemia-hyperviscosity, intraventricular haemorrhage, sepsis, necrotizing enterocolitis, coagulation abnormalities, and congenital anatomical and genetic abnormalities. Intra-uterine growth retardation is associated with a higher stillbirth rate and infant mortality rate in preterm, term and post-term infants.

Increased morbidity in severe early intrauterine growth restriction

OBJECTIVE

To determine the relative frequencies of complications in severe early intrauterine growth-restricted (IUGR) infants.

METHODS

All infants 32 weeks gestation or less with birth weight less than the fifth percentile admitted from January 1991 to December 1998 were identified retrospectively. Two infants were identified for each IUGR case: the subsequent admission with birth weight +/-100 g of the case, and the subsequent admission with the same gestational age. Infants with multiple congenital anomalies, congenital infections or admission after 48 hours of age were excluded. Maternal and neonatal demographic data, neonatal morbidity and mortality until discharge were gathered by chart review.

RESULTS

A total of 39 IUGR identified infants met criteria, with 41 gestational age infants and 33 birth weight infants. Mean birth weights and gestational ages for the IUGR group, gestational age group, and birth weight group were 744 g and 29.6 weeks, 1370 g and 29.7 weeks, and 781 g and 25.5 weeks respectively. Mortality was higher for IUGR infants than gestational age infants (20.5 vs 0%), but less than the birth weight infants (30%). In surviving infants, total ventilator days, total oxygen days, days to full feeds, and patent ductus arteriosis, were higher for IUGR infants than gestational age infants, but less than birth weight infants. Hypoglycemia, direct hyperbilirubinemia, necrotizing enterocolitis (NEC), thrombo-cytopenia, chronic lung disease and feeding difficulties occurred more frequently in IUGR infants than in both other groups. Length of stay for survivors and incidence of retinopathy of prematurity (ROP) was similar for the IUGR and birth weight infants.

CONCLUSIONS

Infants born prematurely who are also severely IUGR have higher neonatal morbidity and mortality when compared to infants of similar gestational age. The surviving IUGR infants had less intraventricular hemorrhage and periventricular leukomalacia than less mature infants of comparable birth weight, but a similar incidence of ROP and length of stay. They had a higher incidence of NEC, direct hyperbilirubinemia and chronic lung disease, probably due to end-organ damage in utero from chronic placental insufficiency. These findings highlight the unique pattern of mortality and morbidity seen in infants with severe early IUGR.

Clinical microbiology of bacterial and fungal sepsis in very-low-birth-weight infants

Twenty percent of very-low-birth-weight (<1500 g) preterm infants experience a serious systemic infection, and despite advances in neonatal intensive care and antimicrobials, mortality is as much as threefold higher for these infants who develop sepsis than their counterparts without sepsis during their hospitalization. Outcomes may be improved by preventative strategies, earlier and accurate diagnosis, and adjunct therapies to combat infection and protect the vulnerable preterm infant during an infection. Earlier diagnosis on the basis of factors such as abnormal heart rate characteristics may offer the ability to initiate treatment prior to the onset of clinical symptoms. Molecular and adjunctive diagnostics may also aid in diagnosing invasive infection when clinical symptoms indicate infection but no organisms are isolated in culture. Due to the high morbidity and mortality, preventative and adjunctive therapies are needed. Prophylaxis has been effective in preventing early-onset group B streptococcal sepsis and late-onset Candida sepsis. Future research in prophylaxis using active and passive immunization strategies offers prevention without the risk of resistance to antimicrobials. Identification of the differences in neonatal intensive care units with low and high infection rates and implementation of infection control measures remain paramount in each neonatal intensive care unit caring for preterm infants.

Preterm male infants need more initial respiratory and circulatory support than female infants

AIM

The aim of this study was to investigate possible gender-related differences in clinical parameters during the first week of life that could explain the higher morbidity and mortality of preterm male infants.

METHODS

In total, 130 clinical variables were collected from 236 inborn infants (130 male and 106 female infants) with gestational age (GA) < 29 wk. A subgroup of 175 extremely low birthweight infants (ELBW) < 1000 g (n = 86 males; n = 89 females) was analysed separately.

RESULTS

At 6 postnatal h, 60.8% of the male infants needed mechanical ventilation versus 46.2% of the females (p = 0.026). Chronic lung disease (CLD) developed in 36.2% of males versus 9.8% of female infants (p = 0.004). Inotrope support with dopamine was used in more than 50% of the infants; additional inotrope support to dopamine was needed by 19.4% of male and 9.7% of female infants (p = 0.041). The gender-related difference in need for inotrope support was more evident among the ELBW infants; 67.1% of male infants needed inotrope support versus 50.6% of females (p = 0.028). At 12-24 h, male ELBW infants had lower minimum mean arterial blood pressure (mean (SD) 25(4) mmHg vs 28(6) mmHg, p = 0.004)) and lower minimum PaCO2 than females infants (4.3 (1.1) kPa vs 4.7 (0.9) kPa, p = 0.043).

CONCLUSIONS

There are early gender-related differences in need for ventilatory and circulatory support that may contribute to the worse long-term outcome in prematurely born male infants.

Effect of birth order on neonatal morbidity and mortality among very low birthweight twins: a population based study

OBJECTIVE

To study the effect of birth order on the risk for respiratory distress syndrome (RDS), chronic lung disease (CLD), adverse neurological findings, and death in very low birthweight (VLBW; < 1500 g) twins.

METHODS

A population based study of VLBW infants from the Israel National VLBW Infant Database. The sample included all complete sets of VLBW twin pairs admitted to all 28 neonatal intensive care units between 1995 and 1999. Outcome variables were compared by birth order and stratified by mode of delivery and gestational age, using General Estimating Equation models, with results expressed as odds ratio (OR) with 95% confidence interval (CI).

RESULTS

Second twins were at increased risk for RDS (OR 1.51, 95% CI 1.29 to 1.76), CLD (OR 1.36, 95% CI 1.11 to 1.66), and death (OR 1.24, 95% CI 1.02 to 1.51) but not for adverse neurological findings (OR 1.20, 95% CI 0.91 to 1.60). Mode of delivery did not significantly influence outcome. The odds ratio for RDS in the second twin was inversely related to gestational age, and the increased risk for RDS and CLD was found in both vaginal and caesarean deliveries.

CONCLUSIONS

VLBW second twins are at increased risk for acute and chronic lung disease and neonatal mortality, irrespective of mode of delivery.

Narrowing of sex differences in infant mortality in Massachusetts

OBJECTIVES

To examine whether the improved survival of preterm infants has influenced the known male excess in infant mortality.

STUDY DESIGN

We analyzed sex-specific infant mortality using linked birth and death certificates for all 619,811 live born infants in Massachusetts between 1989 and 1995.

RESULTS

Between 1989 and 1995 the male excess in infant mortality decreased by 50%, from 1.6/1000 to 0.8/1000 live births (LB). This narrowing resulted primarily from a more rapid decline in neonatal mortality among male infants (1.5/1000 LB) than among female infants (0.9/1000 LB). The largest declines in the male excess in neonatal mortality occurred among very premature infants (GA < or = 30 weeks) and resulted primarily from a more rapid decrease in male deaths from respiratory distress syndrome.

CONCLUSIONS

The narrowing of the sex difference in mortality between 1989 and 1995 suggests that newer treatments like antenatal steroids, and surfactants may have differentially benefited male infants.

Comparison of the perinatal morbidity and mortality of the presenting twin and its co-twin

OBJECTIVE

To compare the perinatal outcome of the presenting twin to its co-twin.

STUDY DESIGN

All live nonanomalous twin gestations delivered at >25 weeks' gestation between 1984 and 1994 (N=461) were identified. Twin A was compared to twin B regarding the following variables: presentation, Apgar score (AS) <4 at 1 minute, AS <7 at 5 minutes, birth weight, gender, traumatic delivery, meconium-stained amniotic fluid, cord prolapse, need for mechanical ventilation, intraventricular hemorrhage, respiratory distress syndrome, sepsis, seizures, perinatal mortality, and length of nursery stay.

RESULTS

Except for differences in presentation, the perinatal outcome was similar in both twins regarding variables studied. This continued to hold true after subdividing according to mode of delivery, when infants with birth weight < or = 1500 g were considered separately, and when vaginally delivered cephalic twin A was compared to the noncephalic co-twin. However, differences in some outcome variables became evident when pregnancies with only one affected member were analyzed separately.

CONCLUSIONS

When all twin pairs are considered, the outcome of the second-born twin is similar to that of the first-born regardless of the mode of delivery, presentation, or birth weight < or = 1500 g. If only those twin pairs with one affected and one unaffected twin are considered, it becomes apparent that the presenting twin is at increased risk for infection-related morbidities whereas the co-twin is at risk for other complications.

Neuromaturation of multiples

Etiology of preterm birth and degree of maturation are the primary determinants of a preterm infant's survival and complications. Multiple gestation increases the likelihood of preterm birth but its influence on rate of maturation or complications of prematurity has been controversial, primarily because of confounding variables (e.g. race, aetiology of preterm delivery, degree of prematurity and pregnancy complications). Very low birthweight preterm multiples have virtually the same rates of neonatal mortality, complications and neuromaturation as preterm singletons of the same gestational age. There is no advantage of delivering twins or higher order multiples before 30 weeks gestation, unless a fetus decompensates in utero. Survival improves for near term intermediate-size preterm multiples while intrauterine growth decelerates and placental and fetal neuromaturation accelerate. These data and the high fetal death rate at term support delivery of multiples as soon as there is fetal lung maturity, and consideration of elective delivery of twins at 35-38 weeks gestation and triplets at 33-35 weeks gestation.

Respiratory distress in heavier versus lighter twins

We performed a retrospective study of twin pairs under 36 weeks gestation admitted to a regional neonatal unit over a three year period to determine if the larger twin of a twin pair is at increased risk of respiratory distress in the immediate postnatal period compared to the smaller twin. Gestation, gender, birth weight, mode and reason for delivery, birth order, and Apgar at 5 minutes were correlated with the need for added oxygen at 4 hours, the need for ventilation, oxygen requirement at 28 days and mortality. One hundred and twenty-four twin pairs were analyzed with a median gestation of 31 weeks (range 23-35). There were 47 female-female pairs, 40 male-male pairs and 37 mixed pairs. Multiple logistic regression revealed no significant increased risk for ventilation in male, heavier or second twins. The need for oxygen at 4 hours was strongly associated with being male and being the second twin, but not with being the heavier twin. However, on analysis of twins of 28 weeks gestation or above a significant association was found between a persisting oxygen requirement at 4 hours and being male (OR 2.2; 95% CI 1.15-4.16), being the heavier twin (OR 1.9; 95% CI 1.03-3.46), and being the second twin (OR 2.7; 95% CI 1.48-4.99). No association was found between mortality and being male, and being the second or smaller twins.

CONCLUSION

Heavier twins above 28 weeks gestation are at increased risk of short term mild respiratory problems following delivery compared to lighter twins at the same gestation. This is not as strong a factor as birth order or male gender, but it is important to be aware of this in antenatal counselling of the parents as the smaller twin is usually perceived to be at greater risk of morbidity.

Respiratory distress syndrome and birth order in premature twins

OBJECTIVE

To determine the effect of birth order on respiratory distress syndrome (RDS) in the outcome of twins in a large premature population managed in a modern neonatal intensive care unit.

METHODS

An historical cohort study design was used to analyse the neonatal outcomes of 301 premature liveborn twin sibling pairs of between 23 and 31 weeks gestation from the Australia and New Zealand Neonatal Network 1995 database.

RESULTS

Among the 56 twin sibling pairs who were discordant for RDS, the second twin was affected in 41 cases (odds ratio (OR) 2.7, 95% confidence interval (CI) 1.5 to 5.3). The excess risk of RDS in the second twin increased with gestation and was statistically significant for twins above 29 weeks gestation (OR 4.4, 95% CI 1.6 to 15).

CONCLUSIONS

There is a significant increased risk of RDS associated with being the second born of premature twins, which appears to depend on gestation.

A comparison of recent trends in infant mortality among twins and singletons

Overall infant mortality rates have steadily declined in recent years. The goal of this study was to examine whether recent declines in infant mortality were similar for twins and singletons, and to assess the impact of differing birthweight distributions on these relationships. Linked birth and infant death records for 1985-86 and 1995-96 were used to calculate infant mortality rates for twins and singletons for the two time periods. Bootstrap simulations were used to estimate rates of decrease between the two time periods and to determine whether these rates differed between twins and singletons. Between 1985-86 and 1995-96, infant mortality among twins declined significantly faster than among singletons (36% vs. 29%, P < 0.05). This difference was true for both black and white infants (black: 28% for twins vs. 22% for singletons; white: 38% for twins vs. 31% for singletons). Within birthweight categories, infant mortality declined more rapidly among twins than among singletons, although differences were not always significant. Factors and circumstances that contributed to the infant mortality decline in the United States have benefited twins to a greater extent than singletons.

Characteristics of adaptation period for extrauterine life of neonates from multiple pregnancies

Multiple pregnancies pose numerous threats both for foetuses and neonates. The following disorders are encountered among the most important perinatal disturbances: EPH – gestosis, immature labour and premature rupture of foetal membranes. Also during the labour, particularly the second one and the following ones, various lesions that may cause increased incidence of diseases and mortality in this group of neonates [5, 6, 10, 18, 21, 22, 25]. Complications encountered in neonates from multiple pregnancies, resulting both from abnormal conditions of intrauterine development and from perinatal pathology, require still wider studies, particularly within the context of intensified obstetrical care of women with multiple pregnancies [7, 11, 13, 16, 24].

In the years 1996-1998, out of 3883 neonates born in the Chair of Obstetrics and Gynaecology of the Silesian Medical Academy, 152 (3,9%) came from multiple pregnancies. This period included one case of quadruplets, eight cases of triplets and 62 twin pregnancies. Pregnant women were directed to our Chair within the program of multidisciplinary care of women with complicated pregnancies and they also came from the Department of Pathology of Pregnancy in our Chair. In 18 women, treated for infertility, the pregnancy was accomplished as a result of application of various techniques of assisted procreation. In one case – 4 foetuses were indicated, in five cases – three foetuses and in 12 cases – two foetuses.

Multiple births and outcome

The rate of multiple-gestation pregnancies has grown exponentially over the last few decades and is responsible for the steady increase in the birth rate of low-birth weight infants. As a group, infants of multiple-gestation pregnancies have higher mortality and morbidity than singleton pregnancies. The increase in adverse outcomes is related directly to the increased risk for preterm delivery and low-birth weight, and not to the multiple gestation itself. Outcomes for multiple-gestation infants appear to be similar whether conceived spontaneously or through artificial reproductive technology. Efforts to reduce the birth rate of low-birth weight infants should target multiple-gestation pregnancies.

The psychological status at school age of children conceived by in-vitro fertilization

This study assessed the behavioural and psychological profiles of children conceived by in-vitro fertilization (IVF) who are now at school age. A total of 743 IVF children born at one institution and now of school age, over 4 years old, were surveyed with Achenbach questionnaires. Follow-up telephone interviews were conducted with non-responders. The results from the study group were compared to the questionnaire control group using one-tailed t-test with statistical significance set less than 0.05. There was an 84% overall response rate. Sixty-seven per cent returned questionnaires. An additional 17% completed a telephone interview. The study group had no statistically significant increase in the rate of behavioural or psychological problems compared with the control group. There were no statistically significant differences within the study group related to sex or to multiple gestation IVF births. This large group of school-age IVF children has normal psychological development with no identified adverse effect of their status as IVF children. Determining the role, if any, of IVF in the very small number of children with behavioural and psychological problems will require additional study.

Level of anxiety in parents of high-risk premature twins

We attempted to define parental anxiety in a population of parents of high-risk premature twins (mean birth weight 1,493 +/- 227 kg; mean gestational age 33 +/- 3.5 weeks), admitted to III level NICU. We specifically examined the following factors; gestational age of the twins, whether or not the twins had ventilatory support, pulmonary sequelae, major malformations or intra-ventricular hemorrhage, parental gender and highest level of education obtained by the parent. In the immediate pre-discharge period and a month later, a questionnaire (State-Trait Anxiety Inventory) was given to all parents of premature twins presenting for the discharge. The parents of 30 twins entered the study twice, at the discharge of their first twin (mean postnatal age 40 +/- 32 days), and one month later. They included 15 mothers and 11 fathers, aged 33 +/- 5.5 and 33 +/- 4.2 years, and at the second evaluation 11 mothers and 10 fathers, respectively. As case-controls we examined parental anxiety of fifteen consecutive singleton high-risk prematures, with equal gestational age, discharged immediately after. Our results indicate that the parents of high-risk twin and singleton prematures present an elevated, lasting state-trait anxiety level. Pre- and post-discharge parental anxiety is more elevated (not significant) in twinning with respect to the prematurity alone. When assessed separately by parental gender, in both these groups an increased (not significant) anxiety was persistently found in the mothers. We recommend that, although neonatologists generally define the discharge of the high-risk premature based upon the acquired stabilization of vital parameters, they pay special attention to the twin group we have identified which is at increased risk for predischarge parental anxiety.

Outcomes of very low birth weight twins cared for in the National Institute of Child Health and Human Development Neonatal Research Network's intensive care units

OBJECTIVE

The study's aim was to compare outcomes of very low birth weight twins with those of matched singletons.

STUDY DESIGN

With data from the Neonatal Research Network registry (May 1991 to December 1994), univariable and multivariable comparisons of very low birth weight twin pairs and singletons were performed in 2 subgroups: (1) all paired twins and singletons with birth weights between 401 and 1500 g and (2) all paired twins and singletons born at <28 weeks' gestation.

RESULTS

Twins constituted 19% of infants admitted with very low birth weight. Mothers of twins were more likely to receive prenatal care, have labor, have cesarean delivery, and receive antenatal glucocorticoids. Twins were more likely to have respiratory disease and to receive surfactant. Second-born twins had more early respiratory disease but similar longer-term outcomes. The risks of death, chronic lung disease, and grade III or IV intracranial hemorrhage were similar in twins and singletons.

CONCLUSIONS

Although very low birth weight twins compose a sizable proportion of admissions, in National Institute of Child Health and Human Development Neonatal Research Network intensive care units, twins and singletons have similar outcomes.

Multifetal pregnancy reduction is not associated with an increased risk of intrauterine growth restriction, except for very-high-order multiples

OBJECTIVE

Our purpose was to investigate whether multifetal pregnancies reduced to twins have an increased risk of intrauterine growth restriction and discordant birth weight.

STUDY DESIGN

This retrospective cohort study investigated the rates of birth weight discordance > 20% and intrauterine growth restriction using both twin and singleton birth weight curves in 441 twin deliveries after multifetal pregnancy reduction (233 reduced from triplets, 156 from quadruplets, and 52 from quintuplets or greater) compared with 136 nonreduced dichorionic twins.

RESULTS

No significant difference was found in the frequency of birth weight discordance and in the overall incidence of intrauterine growth restriction by both twin and singleton birth weight curves when pregnancies that underwent multifetal pregnancy reduction were compared with the control group. There was, however, an almost twofold increase in the rate of intrauterine growth restriction in pregnancies with a starting fetal number of 5 or more (23.1%) compared with that in those reduced from triplets or quadruplets (12.1%) when the twin curve standard was used (P = .03). This difference disappeared when these groups were compared with a singleton nomogram.

CONCLUSION

This study suggests that multifetal pregnancy reduction is not associated with an increased risk of intrauterine growth restriction unless the starting fetal number is > or = 5. This finding provides a further rationale to avoid transferring excessive numbers of preembryos after in vitro fertilization.