Low weight/length ratio to assess risk of cerebral palsy and perinatal mortality in twins

Quantile contours and allometric modelling for risk classification of abnormal ratios with an application to asymmetric growth-restriction in preterm infants

We develop an approach to risk classification based on quantile contours and allometric modelling of multivariate anthropometric measurements. We propose the definition of allometric direction tangent to the directional quantile envelope, which divides ratios of measurements into half-spaces. This in turn provides an operational definition of directional quantile that can be used as cutoff for risk assessment. We show the application of the proposed approach using a large dataset from the Vermont Oxford Network containing observations of birthweight (BW) and head circumference (HC) for more than 150,000 preterm infants. Our analysis suggests that disproportionately growth-restricted infants with a larger HC-to-BW ratio are at increased mortality risk as compared to proportionately growth-restricted infants. The role of maternal hypertension is also investigated.

Ultrasound study of fetal movements in singleton and twin pregnancies at 12-19 weeks

Objective To evaluate fetal behavioral differences between singleton and twin fetuses before 20 weeks of gestation using four-dimensional (4D) ultrasound. Methods 4D ultrasound was used to examine fetal movements in 58 singleton and 48 twin normal fetuses at 12-19 weeks. The frequencies of eight fetal movements were assessed through 15-min recordings. The fetuses were divided into two gestational age groups (12-13 and 14-19 weeks) to evaluate the changes with advancing gestation in twin versus singleton fetuses. Results Arm and general movements were the most frequent movements in singleton fetuses, whereas only general movement was significantly more frequent than the other seven fetal movements in twin fetuses at 12-13 weeks. At 14-19 weeks, frequencies of arm and leg movements were significantly higher than those of the other six movements in singleton fetuses, while only arm movement was significantly more frequent than the other fetal movements in twin fetuses. Comparisons of fetal movements between singleton and twin fetuses revealed that only arm movement showed a significant difference at 12-13 weeks, while the frequencies of all movements in singleton fetuses were significantly higher than those in twin fetuses at 14-19 weeks. Conclusion Our results suggest that the limitation of available space and crowding of twin fetuses with advancing gestation may have a marked impact on twin fetal movements compared with singleton fetuses, even in the first half of pregnancy. Further studies are needed to assess whether decreased fetal movements in twin pregnancy can affect fetal and neonatal development and maturation before and after birth.

Choosing the Best Newborn Anthropometric Measure Associated With the Risks and Outcomes of Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is associated with various prenatal risks and postnatal adverse outcomes. The aim of this study is to choose the most sensitive newborn anthropometric measure, which is closely associated with IUGR-related risks and outcomes, to substitute IUGR after delivery. Data were obtained from the Collaborative Perinatal Project, a multicenter prospective cohort study in the United States from 1959 to 1976. Maternal heavy smoking and severe hypertensive disorders during pregnancy, neonatal polycythemia and hypothermia, low intelligence quotient (<70) at age 7 years were chosen as IUGR-related risks and outcomes. Eight anthropometric measures at birth were tested by logistic regression model. Birth weight-to-head circumference (W/HC) had the largest odds ratio (OR) for neonatal polycythemia (OR = 1.8, 95% confidence interval [CI] = 1.5-2.0), severe hypertensive disorders (OR = 1.9, 95% CI = 1.5-2.2), and maternal heavy smoking (OR = 1.9, 95% CI = 1.7-2.1) during pregnancy. It also had the highest summary OR (9.3). Thus, W/HC may be a good measure for IUGR.

Neurodevelopmental outcomes of twins

In population-based studies, the prevalence of neurodevelopmental disability is consistently higher in twins than singletons. This is largely because birth weight and gestational age (GA) distributions of twin births are shifted to the left when compared with singleton births, and lower birth weight and lower GA are associated with increased risk of neurodevelopmental disability. From a pathophysiologic perspective, a question of interest is whether neurodevelopmental outcomes of twins differ from singletons after controlling for covariates. If significant differences in outcomes persist, this would suggest that the twining process itself or something intrinsic to shared life in the womb may be responsible for observed differences. From a clinical perspective, when counseling parents at risk for preterm delivery of twins, it is useful to understand how twin outcomes compare relative to singleton outcomes at the same birth weight or GA. The purpose of this review is to examine the long-term neurodevelopmental outcomes of twins compared with singletons with control for important covariates.

Fetal programming: the perspective of single and twin pregnancies

Multiple pregnancy is associated with increased risk of adverse consequences for both mother and fetus(es), including increased rates of maternal hypertension and pre-eclampsia, spontaneous abortion, Caesarean delivery, low birthweight, birth prematurity, perinatal mortality, admission to neonatal intensive care and extended length of care, respiratory distress, cerebral palsy, developmental delay, contact with disability services and mortality to age 5 years. Premature birth, which affects 97% of triplets and 53.3% of twins in Australia, is not the sole factor involved. The rate of multiple pregnancy in Australia is 1.7%. This compares to 22.1% for pregnancies resulting from assisted reproduction technology (ART). As a result, 21.8% of babies born from ART are from a multiple pregnancy, in comparison to the USA where the majority of babies born from ART are from a multiple pregnancy. Additionally, the population rate of multiple births is rising due to the more frequent use of ART and continued multi-embryo transfers, which is operating against a background of rising implantation rates within ART clinics. Twins have been of interest from a programming perspective. However, analysis of associations between crude birthweight and subsequent metabolic risk factors or mortality in adulthood from chronic disease indicate that adaptations in pregnancy to support multi-fetal growth are not identical to fetal growth restriction in singleton pregnancies. Indeed, the process of ‘maternal constraint’ is incompletely understood and confounds such comparisons. From a programming perspective, it is a challenge to identify in twin pregnancies the transition from physiological adaptation to pathological growth restriction. Growth disparity between twins has been more illuminating of subtle adverse effects for the smaller of twin pairs in both blood pressure and insulin resistance in adulthood. Interestingly, these effects can be observed in both dizygotic and to a lesser degree in monozygotic twins, which indicates a role for both genetic and environmental factors in these measures. This suggests that, consistent with experimental studies in other species, the relationship between impaired growth in utero and chronic disease in later life is not simply mediated by a common genetic pathway.

Nonresponsiveness of cerebral p53-MDM2 functional circuit in newborn rat pups rendered IUGR via uteroplacental insufficiency

Severe uteroplacental insufficiency causes cerebral apoptosis in the fetus. Moderate uteroplacental insufficiency causes intrauterine growth retardation (IUGR) and increases the risk of postnatal neurological morbidity. In the rat, uteroplacental insufficiency and IUGR affect cerebral gene expression of Bcl-2 and predispose the newborn IUGR rat toward cerebral apoptosis when challenged with perinatal hypoxia. Expression of Bcl-2, as well as the proapoptotic protein Bax, is regulated by p53. p53 also induces MDM2 transcription, which functions to limit further p53-induced apoptosis. The predisposition of the IUGR fetus toward cerebral apoptosis suggests that the p53-MDM2 "functional" circuit may be perturbed in the newborn IUGR rat brain. We hypothesized that MDM2 cerebral expression does not increase in response to increased p53 expression or increased levels of phospho-p53 (Ser15), an activated form of p53. To prove this hypothesis, we induced IUGR through bilateral uterine ligation of the pregnant rat. Uteroplacental insufficiency significantly increased p53 mRNA, total p53 protein, and phospho-p53 (Ser15) protein levels in the brain at term. Increased expression of phospho-p53 (Ser15) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells were localized to the CA1 region of the hippocampus, the subcortical and periventricular white matter, and the amygdala of the IUGR rat brain. In contrast, uteroplacental insufficiency decreased cerebral MDM2 mRNA and phospho-MDM2 (Ser166) protein levels in the IUGR rat pups. We conclude that the cerebral MDM2 response to increased p53 expression is not present in the newborn IUGR rat pup, and we speculate that this contributes to the predisposition of the IUGR fetus toward perinatal and long-term neurodevelopmental morbidities.

Economic and social implications of multiple birth

This paper provides the background statistics and trends on multiple births. It highlights a number of factors that influence parents with multiples, including social situation, psychological adjustment and economic circumstances. It is often assumed that these areas of concern arise only after the babies have been born, but clinicians should be aware that many are seen in the antenatal period as well. Apart from the socioeconomic cost to individual families, multiple births also carry a cost to society. A number of self-help groups and voluntary organisations can assist parents of multiples. This is especially important if parents find that family and friends cannot or will not come forward.

Do multiple gestations raise the risk of cerebral palsy?

There is an increased risk of CP in multiple as compared with singleton pregnancies, and the higher the number of fetuses the greater is the prevalence of CP. Although LBW and preterm birth are the most significant risk factors for CP, the disadvantage of twins is apparent near term. Moreover, the excessive risk is not only the result of over-representation of multiples among premature babies, but seems to be associated with circumstances that are unique to the twinning process. The risk of CP should be acknowledged not only when a multiple pregnancy is diagnosed, but also when counseling infertility patients in whom iatrogenic multiple pregnancies are an actual risk.

Multiple birth and cerebral palsy in Europe: a multicenter study

BACKGROUND

A European multicenter study (Surveillance of Cerebral Palsy in Europe, SCPE) was used to describe changes over time in multiple birth rates and cerebral palsy (CP) rates among multiple born infants, to compare CP rates and clinical types between multiples and singletons, and to analyse the influence of birth order in twins.

METHODS

Data were collected from 12 European population-based CP registers on 6613 children born in 1975-90, as well as demographic data.

RESULTS

The rate of multiple birth in the populations increased from 1.9% in 1980 to 2.4% in 1990, and the proportion of multiples among CP infants increased from 4.6% in 1976 to 10% in 1990. Multiples have a four times higher rate of CP than singletons [7.6 vs. 1.8 per 1000 live births, relative risk (RR) 4.36; 95% confidence interval (CI) 3.76-4.97] overall. The risk is marginally higher in multiples with birthweight > 2500 g (RR 1.60; 95% CI 0.95-2.28) and born at term (RR 1.65; 95% CI 0.91-2.40), and there is no difference in the risk for the low-birthweight and preterm groups. Correcting for differences in gestational age and birthweight, the clinical type of CP was the same in multiples and singletons. Twin CP infants are more often second than first born (56% vs. 44%, p < 0.05).

CONCLUSIONS

Multiple born infants have a four times higher risk of developing cerebral palsy than singletons, mainly related to the higher risk of preterm birth in multiples. As the rate of multiples doubled through the 1980s, cerebral palsy cases in multiples increased in the same period.

New developments in the management of preterm labor

Current management of preterm labor has not changed the incidence of preterm delivery; therefore, significant research effort has been concentrated on the search for new methods of management. New tocolytics like inhibitors of cyclooxygenase 2 and nitric oxide donors have been tested in animal models and in preliminary clinical trials with promising results. Inhibition of cervical ripening may be one alternative to tocolysis. This new approach has a potential to be a valuable method of management of preterm labor if human studies confirm the promising results reported in animals. Growing evidence suggests that premature delivery may be associated with infection or fetal growth abnormalities, with dire consequences to the fetus. If these associations are to be included in risk and benefit assessment, then inhibition of preterm labor may prove to be detrimental to the fetus.

Advances in prevention and treatment of cerebral palsy

In recent years there have been a number of advances in understanding of predisposing and protective factors in the development of cerebral palsy in infants. Multiple gestation births, maternal infection, and maternal and fetal thrombophilic conditions all predispose to the development of CP in the infant. Opportunities for prevention of CP may develop from an improved understanding of these factors and their mechanisms of operation. Similar progress has been made in the evaluation of treatments for CP and the effects of these treatments on the individual's impairment, function, and disability. Selective posterior rhizotomy and Botulinum toxin A are now widely used in the treatment of spasticity. The challenge remains to determine how effectively these promising interventions can alter long-term function and quality of life outcomes in children and adults with CP.

Uteroplacental insufficiency alters cerebral mitochondrial gene expression and DNA in fetal and juvenile rats

Uteroplacental insufficiency increases the risk of perinatal and long-term neurologic morbidity by depriving the fetus of oxidative substrate and causing intrauterine growth retardation. Skeletal muscle and liver from growth retarded fetal and juvenile rats respond to this deprivation by altering mitochondrial gene expression and function. The objective of this study was to determine whether cerebral mitochondrial mRNA is similarly altered in fetal and juvenile growth retarded rats and to correlate these alterations with mitochondrial DNA and marker protein levels. To fulfill this objective, mRNA levels of four important mitochondrial proteins were quantified using RT-PCR in growth retarded and sham-operated control fetal and juvenile rat brains; these proteins were NADH-ubiquinone oxireductase subunit 4, subunit C of the F1F0-ATPase, and the adenine nucleotide transporters 1 and 2. Mitochondrial DNA/nuclear DNA ratios and mitochondrial 60 kD marker protein levels were also quantified in growth retarded and sham-operated control fetal and juvenile rat brains using PCR and Western Blotting, respectively. Cerebral mRNA levels of all four proteins were increased in the IUGR fetuses and decreased in the IUGR juvenile animals. Cerebral mitochondrial/nuclear DNA ratios and mitochondrial marker protein levels were not significantly altered in the IUGR fetuses; however, both were significantly diminished in IUGR juvenile pups. These studies suggest that the metabolic stresses associated with uteroplacental insufficiency in the rat cause altered fetal and postnatal cerebral mitochondrial mRNA and DNA levels.

Nutrition and multifetal pregnancy

Largely because of assisted reproduction, the rate of multifetal pregnancy is rising rapidly in the United States. Accordingly, dietitians are increasingly being called upon to provide nutrition services for these high-risk pregnancies. This article gives an overview of the incidence of and risks associated with multifetal pregnancy and reviews studies that contribute to our knowledge of nutrition and multifetal pregnancy. Practice guidelines for promoting healthy outcomes based on the best available scientific data are suggested. Guidelines for weight gain for twin and triplet pregnancy, dietary intake, and supplement use are included. Suggested practice guidelines for multifetal pregnancy include a positive rate of weight gain early in pregnancy, the use of prepregnancy weight status to determine total weight gain goals in twin pregnancy, a 50-lb weight gain goal for triplet pregnancy, and higher minimal number of servings of foods from several of the Food Guide Pyramid groups. The need for additional information on the effects of nutritional status on the course and outcome of multifetal pregnancy is critical. Preliminary evidence of the benefits of nutrition services suggests that both the incorporation of dietetics services into care programs and additional research on nutrition and multifetal gestation are warranted.