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

A Systematic Review: Is Early Fluid Restriction in Preterm Neonates Going to Prevent Bronchopulmonary Dysplasia?

Preterm birth causes constant challenges, with bronchopulmonary dysplasia (BPD) being a major concern. Immediately after birth, it takes time to establish feeding between the mother and the premature baby. During this time, the telological shifting of fluid from extracellular space to intracellular space will help the baby; this transition should be smooth. Both normal physiologic changes and pathophysiologic events are capable of disrupting this delicate fluid shifting that occurs in very low-birth-weight infants during the first week of life. The immaturity of the renal system and evaporative losses complicate this process. This lack of fluid displacement can be associated with an increased amount of water in the lungs and reduced lung compliance. This can lead to the need for more ventilatory support and a higher oxygen requirement, which, in turn, leads to lung damage. The fluid restriction is also associated with complications such as severe dehydration, intracranial hemorrhage, and bilirubin toxicity. However, the administration of large amounts of fluid and salt is associated with an increased incidence of patent ductus arteriosus, BPD, necrotizing enterocolitis, and intraventricular hemorrhage. There were studies conducted in both the pre-surfactant and surfactant eras that were inconclusive regarding fluid restriction in BPD. We only included very recent studies. This systematic review attempts to summarize the current evidence, focusing on the efficacy and safety of early fluid management in preterm infants. This reduces the risk of BPD and improves outcomes for premature infants. As we know, intact survival is very important. Our review supported the early fluid restriction.

Comparison of neonatal outcomes between multiples and singletons among very low birth weight infants: the Korean Neonatal Network cohort study

OBJECTIVE

To compare neonatal outcomes between multiples and singletons among very low birth weight infants, this was a prospective cohort study that was conducted by collecting data registered in the Korean Neonatal Network database.

METHODS

From January 2013 to December 2016, there were 8265 infants in the Korean Neonatal Network database, and 2958 of them were from multiples. Among them, 2636 infants were twins, 308 infants were triplets, and 14 infants were quadruplets. Maternal and neonatal variables including and mortality major morbidity were compared. Finally, the predicted rates of major morbidity between singletons and multiples.

RESULTS

Multiples had higher gestational age, birth weight, Apgar score at 5 min, rates of cesarean section and artificial reproductive technology but lower maternal hypertension, oligohydramnios, chorioamnionitis rates and Clinical Risk Index for Babies scores II without base excess than the singletons. In univariate analysis, multiples had a lower incidence of respiratory distress syndrome, bronchopulmonary dysplasia, and sepsis. The mortality rate was not significantly different for overall gestational ages except for those born at ≤26 weeks of gestation. In multivariate logistic analysis, the incidences of intraventricular hemorrhage (grade ≥3), and retinopathy of prematurity requiring treatment were significantly higher than the singletons.

CONCLUSIONS

Mortality was not significantly different between multiples and singletons according to overall gestational age, except for multiples born at ≤26 weeks. A significant higher risk of intraventricular hemorrhage and retinopathy of prematurity requiring treatment was found in multiples. A new strategy to improve the mortality of immature multiples born at ≤26 weeks of gestation should be developed.

Birth order and morbidity and mortality to hospital discharge among inborn very low-birthweight, very preterm twin infants admitted to neonatal intensive care: a retrospective cohort study

OBJECTIVE

To know the association of birth order with the risk of morbidity and mortality in very low-birthweight (VLBW) twin infants less than 32 weeks' gestational age (GA).

DESIGN

Retrospective cohort study.

SETTING

Infants admitted to the collaborating centres of the Spanish SEN1500 neonatal network.

PATIENTS

Liveborn VLBW twin infants, with GA from 23⁺⁰ weeks to 31⁺⁶ weeks, without congenital anomalies, admitted from 2011 to 2020. Outborn patients were excluded.

MAIN OUTCOME MEASURES

Respiratory distress syndrome (RDS), patent ductus arteriosus, bronchopulmonary dysplasia (BPD), necrotising enterocolitis, major brain damage (MBD), late-onset neonatal sepsis, severe retinopathy of prematurity, survival and survival without morbidity. Crude and adjusted incidence rate ratios were calculated.

RESULTS

Among 2111 twin pairs included, the second twin had higher risk (adjusted risk ratio (aRR) of RDS (aRR 1.08, 95% CI 1.03 to 1.12) and need for surfactant (aRR1.10, 95% CI 1.05 to 1.16). No other significant differences were found, neither in survival (aRR 1.01, 95% CI 0.99 to 1.03) nor in survival without BPD (aRR 1.02, 95% CI 0.99 to 1.05), survival without MBD (aRR 1.02, 95% CI 0.99 to 1.06) nor in survival without major morbidity (aRR 0.97, 95% CI 0.92 to 1.03). However, second twins born by caesarean section (C-section) after a vaginally delivered first twin had less overall survival and survival without MBD.

CONCLUSION

In modern perinatology, second twins are still more unstable immediately after birth and require more resuscitation. After admission to the neonatal intensive care unit, they are at increased risk of RDS, but not other conditions, except for second twins delivered by C-section after a first twin delivered vaginally, who have decreased overall survival and survival without major brain injury.

Protocol versus practice: Deviations from guidelines in low-risk twin deliveries in the United States

BACKGROUND

Medical guidelines recommend vaginal delivery for low-risk twin pregnancies because cesareans increase the probability of maternal morbidity and mortality. Yet, vaginal delivery rates for twins are considerably lower than for comparable singletons. One explanation for this disparity argues that greater risk associated with twins warrants increased surgical intervention. An alternative explanation is that twin deliveries are more likely to deviate from protocols that advise vaginal birth.

METHODS

Using the 2017 Natality Detail File (N = 3,197,401), we measured alignment of vaginal birth and trial of labor (TOL) with the American College of Obstetricians and Gynecologists' guidelines for twin and singleton no-indicated-risk births. We calculated predicted probabilities for the population and by maternal race/ethnicity to assess whether low rates of vaginal births among twins are explained by associated risk factors, or by deviations from recommended delivery methods.

RESULTS

Overall, 31.2% of twins were born vaginally compared with 79.4% of singletons. Controlling for indicated risks, the predicted probability of vaginal birth for twins was 0.49 and 0.85 for singletons. The predicted probability of TOL for twins was 0.18 and 0.47 for singletons. Maternal race/ethnicity was only weakly associated with mode of delivery. These findings indicate that no-indicated-risk twin pregnancies, across maternal racial/ethnic categories, have lower probabilities of vaginal birth and TOL than would be expected with widespread adherence to current guidelines.

CONCLUSIONS

Given the life-threatening consequences that may result from unnecessary surgical procedures, our findings highlight the need for further research to illuminate medical and nonmedical mechanisms driving nonadherence to clinical guidelines for twin births.

Medicaid Accountable Care Organizations and Childbirth Outcomes

Some states have adopted Accountable Care Organization (ACO) models to transform their Medicaid programs, but little is known about their impact on health care outcomes and costs. Medicaid ACOs are uniquely positioned to improve childbirth outcomes because of the number of births covered by Medicaid. Using Healthcare Cost and Utilization Project hospital data, we examined the relationship between ACO adoption and (a) neonatal and maternal outcomes, and (b) cost per birth. We compared outcomes in states that have adopted ACO models in their Medicaid programs with adjacent states without ACO models. Implementation of Medicaid ACOs was associated with a moderate reduction in hospital costs per birth and decreased cesarean section rates. Results varied by state. We found no association between Medicaid ACOs and several birth outcomes, including infant inpatient mortality, low birthweight, neonatal intensive care unit utilization, and severe maternal morbidity. Improving these outcomes may require more time or targeted interventions.

Morbidity and mortality of very low birth weight multiples compared with singletons

BACKGROUND

Previous studies comparing the neonatal outcome of very low birth weight (VLBW) multiples and singletons have suggested a worse outcome for multiples at gestational ages on the limits of viability.

OBJECTIVES

The objective of this study is to determine the neonatal mortality and morbidity of VLBW multiples compared to singletons.

METHODS

This is a retrospective study including all infants registered in the Spanish network for infants under 1500 g (SEN1500), over a 12-year period (from 2002 to 2013). Mortality and major morbidities were compared between singletons and multiples.

RESULTS

About 32,770 infants were included: 21,123 singletons (64.5%) and 11,647 multiples (35.5%), with a mean gestational age of 29.5 weeks (22-38), and mean birth weight of 1115 g (340-1500). When adjusted by other perinatal factors, multiple pregnancy has a significantly higher risk of mortality than singleton pregnancy (odds ratio (OR) 1.15; IC 95% 1.05-1.26, p = .002), but not a higher risk of major morbidity or composite adverse outcome. In the subgroup of infants born before 26 weeks, multiples showed a higher risk of mortality (63.9% versus 51%, OR 1.7; 95% CI 1.47-1.96) and a higher risk of composite adverse outcome (88.9% versus 81.5%, OR 1.82, 95% CI 1.28-2.24).

CONCLUSIONS

In preterm infants born with less than 1500 g, multiple pregnancy is a prognostic factor that can slightly increase mortality. Extremely preterm infants born before 26 weeks have a greater risk of mortality and major morbidity if they come from a multiple pregnancy.

Impact of routine transvaginal ultrasound monitoring of cervical length in twins on administration of antenatal corticosteroids

OBJECTIVE

To evaluate whether routine measurement of cervical length (CL) by transvaginal ultrasound (TVU) in twin pregnancies can enable identification of women who will give birth before 34 weeks and require antenatal corticosteroids (ACSs), and whether it can limit their administration to women who will give birth later.

STUDY DESIGN

Retrospective comparative study in two tertiary referral centers in France. Women with twin gestations followed in two tertiary university hospital maternity units and who delivered from January 1, 2007 to December 31, 2009 were included. In one center, TVU was targeted to women with cases of suspected preterm labor, while the other center used it monthly for all twin pregnancies. The main outcome measure was the administration of a full course of ACS to twins delivered before 34 weeks.

RESULTS

Two hundred and seventy women were eligible in the "targeted use" group, and 296 women in the "routine use" group. The rate of administration of at least one full course of ACS for twins born before 34 weeks did not differ between the two groups (85.0% in the targeted use group and 90.0% in the routine use group, P=0.40), but the rate of such administration for those born after 34 weeks was lower in the targeted use group (25.7% vs. 81.2%, P<0.01). On adjusting for confounders using logistic regression modeling, no significant difference in ACS administration before 34 weeks was found between the two groups [adjusted odds ratio (aOR), 0.71, 95% confidence interval (CI), 0.39-1.30].

CONCLUSION

Routine monitoring performed every month of CL with TVU does not affect the rate of administration of ACS to twins born before 34 weeks, but is associated with a higher rate of such administration for those born later in the specific center of the study.

Twin's Birth-Order Differences in Height and Body Mass Index From Birth to Old Age: A Pooled Study of 26 Twin Cohorts Participating in the CODATwins Project

We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI.

Perinatal Outcome of the Second Twin at a Tertiary Care Center in India

PURPOSE

This cross-sectional observational study was undertaken to assess perinatal outcome of the second twin in respect to gestational age, presentation, mode of delivery, and birth weight.

METHODS

Seventy women with confirmed twin pregnancy were admitted and managed in a tertiary care teaching hospital in Kolkata, India from May 2008 to April 2009. All relevant data were recorded and analyzed statistically by simple proportions and χ² test.

RESULTS

Women with frequent antenatal visits had highly favorable perinatal outcome than those with fewer or no visits in this hospital (p < 0.001). Higher perinatal mortality was observed among preterm than term (p < 0.01) cases, and among low birth weight than normal babies (p < 0.05). Second twins in vertex-vertex presentation encountered higher perinatal mortality compared to those in vertex-nonvertex and nonvertex-other presentations (p < 0.05). Perinatal outcome was unfavorable when both delivered vaginally than for both cesarean deliveries and cesarean after first vaginal delivery (p < 0.01). Preterm labor was the most frequently observed maternal complication. Birth asphyxia and perinatal mortality were common among second than first twins.

CONCLUSIONS

Gestational age, presentation, mode of delivery, and birth weight are the significant determinants of perinatal outcome of the second twin. Women with frequent antenatal care show favorable outcome. The second twin is at higher risk of perinatal morbidity and mortality than the first twin.

Trends in Morbidity and Mortality of Extremely Preterm Multiple Gestation Newborns

OBJECTIVES

To examine the risk of mortality and major morbidities in extremely preterm multiple gestation infants compared with singletons over time.

METHODS

This is a retrospective study of 15,402 infants born ≤27 weeks' gestation, admitted to NICUs in the Australian and New Zealand Neonatal Network from 1995 to 2009. Mortality and major morbidities were compared between singletons and multiples across three 5-year epochs.

RESULTS

Extreme preterm multiples were more likely to have lower birth weight; higher maternal age; and higher rates of assisted conception, antenatal steroid use, and cesarean delivery compared with singletons. The mortality rate was significantly higher in multiples compared with singletons even as there was a trend of decreasing gestational-age stratified mortality in multiples over the time period investigated. The rates of major morbidities or composite adverse outcomes were not different between multiples and singletons across all epochs. The adjusted odds ratio (AOR) for mortality in multiples was significantly higher in multiples compared with singletons (AOR 1.20, 95% confidence interval [CI] 1.08-1.34). There were no differences in the adjusted odds for poor outcomes in multiples compared with singletons in the most recent epoch: mortality (AOR 1.00, 95% CI 0.84-1.19), major morbidity (0.95, 95% CI 0.81-1.10), and composite adverse outcome (0.96, 95% CI 0.83-1.11).

CONCLUSIONS

Over the 15-year period, the odds for mortality in extremely preterm NICU infants of multiple gestation was significantly higher compared with singletons. The adjusted odds of poor outcomes in multiples were not significantly different from that of singletons in the most recent epoch.

Application of a validated prediction model for in vitro fertilization: comparison of live birth rates and multiple birth rates with 1 embryo transferred over 2 cycles vs 2 embryos in 1 cycle

OBJECTIVE

The purpose of this study was to use a validated prediction model to examine whether single embryo transfer (SET) over 2 cycles results in live birth rates (LBR) comparable with 2 embryos transferred (DET) in 1 cycle and reduces the probability of a multiple birth (ie, multiple birth rate [MBR]).

STUDY DESIGN

Prediction models of LBR and MBR for a woman considering assisted reproductive technology developed from linked cycles from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System for 2006-2012 were used to compare SET over 2 cycles with DET in 1 cycle. The prediction model was based on a woman's age, body mass index (BMI), gravidity, previous full-term births, infertility diagnoses, embryo state, number of embryos transferred, and number of cycles.

RESULTS

To demonstrate the effect of the number of embryos transferred (1 or 2), the LBRs and MBRs were estimated for women with a single infertility diagnosis (male factor, ovulation disorders, diminished ovarian reserve, and unexplained); nulligravid; BMI of 20, 25, 30, and 35 kg/m2; and ages 25, 35, and 40 years old by cycle (first or second). The cumulative LBR over 2 cycles with SET was similar to or better than the LBR with DET in a single cycle (for example, for women with the diagnosis of ovulation disorders: 35 years old; BMI, 30 kg/m2; 54.4% vs 46.5%; and for women who are 40 years old: BMI, 30 kg/m(2); 31.3% vs 28.9%). The MBR with DET in 1 cycle was 32.8% for women 35 years old and 20.9% for women 40 years old; with SET, the cumulative MBR was 2.7% and 1.6%, respectively.

CONCLUSION

The application of this validated predictive model demonstrated that the cumulative LBR is as good as or better with SET over 2 cycles than with DET in 1 cycle, while greatly reducing the probability of a multiple birth.

Do very preterm twins and singletons differ in their neurodevelopment at 5 years of age?

OBJECTIVE

Twins have inconsistently shown poorer outcomes than singletons. Although a high proportion of twins are born very preterm, data are sparse on the long-term outcomes in very preterm twins. The objective of this study was to compare mortality and neurodevelopmental outcomes of very preterm singletons and twins and to study outcomes in relation to factors specific to twins.

DESIGN

Birth cohort study Etude Epidemiologique sur les Petits Ages Gestationnels (EPIPAGE).

SETTING

Nine regions in France.

PATIENTS

All very preterm live births occurring from 22 to 32 weeks of gestation in all maternity wards of nine French regions in 1997 (n=2773).

MAIN OUTCOMES MEASURES

Neurodevelopmental status, including cerebral palsy, and a cognitive assessment with the Kaufman Assessment Battery for Children, with scores on the Mental Processing Composite (MPC) scale, was available for 1732 and 1473 children at 5 years of age, respectively.

RESULTS

Among live births, twins had higher hospital mortality than singletons (adjusted (a)OR: 1.4 (95% CI 1.1 to 1.9)). Among survivors, there was no crude difference at 5 years between twins and singletons in the prevalence of cerebral palsy (8.0% vs 9.1%, respectively), MPC <70 (9.5% vs 11.1%) and mean MPC (94.6 vs 94.4). However, after adjustment for sex, gestational age, intrauterine growth restriction and social factors, twins were more likely to have lower MPC scores (mean difference: -2.4 (95% CI-4.8 to 0.01)). Live born twins had a higher risk of mortality when birth weight discordance was present (aOR:2.9 (95% CI 1.7 to 4.8)), but there were no differences in long-term outcomes.

CONCLUSIONS

Compared with very preterm singletons, twins had higher mortality, no difference with respect to severe deficiencies, but slightly lower MPC scores at 5 years.

Routine cervical length and fetal fibronectin screening in asymptomatic twin pregnancies: is there clinical benefit?

OBJECTIVE

To determine whether routine cervical length (CL) and fetal fibronectin (fFN) screening is associated with improved clinical outcomes in asymptomatic patients with twin pregnancies.

STUDY DESIGN

We compared outcomes between two large cohorts of twin pregnancies who delivered in New York City from 2003 to 2012. One cohort (n = 532) was managed by a single group practice, delivered at one large academic medical center, and underwent routine serial CL and fFN screening. The second cohort (n = 456) delivered at a second large academic center and only underwent CL and fFN testing as clinically indicated. Outcomes measured include cerclage placement, preterm birth (PTB), spontaneous PTB (sPTB), and antenatal corticosteroid (ACS) exposure.

RESULTS

Rates of cerclage placement, PTB, and SPTB were similar between the two groups. However, routine CL and fFN screening was associated with improved rates of ACS exposure in patients who delivered <34 weeks (91.3% versus 74.7%, p = 0.005) and 34-36 6/7 weeks (41.3% versus 13.9%, p < 0.001) without increased ACS exposure in women who delivered at term. In patients who delivered <34 weeks, routine CL and fFN screening was significantly associated with improved rates of ACS exposure within 1-14 days of delivery and within 1-7 days of delivery.

CONCLUSION

In twin pregnancies, routine CL and fFN screening does not reduce the risk of PTB or SPTB. However, the routine use of these tests is associated with significantly improved ACS exposure and timing for women who deliver preterm without increasing ACS exposure to women who deliver at term.

Prevalence and predictors of early breastfeeding among late preterm mother-infant dyads

BACKGROUND

Although late preterm infants (LPIs), at 34(0/7)-36(6/7) weeks of gestation, are reported to have suboptimal rates of breastfeeding, there is a lack of quantitative evidence describing this trend. This study examined the prevalence of breastfeeding initiation and factors associated with breastfeeding non-initiation within a Pennsylvania population-based cohort of late preterm mother-infant dyads.

SUBJECTS AND METHODS

Descriptive statistics and odds ratios were used to assess and compare breastfeeding initiation rates in 2003-2009 among LPI mothers (n=62,451) and their infants (n=68,886) with moderately preterm (n=17,325) and term (n=870,034) infants. Binary logistic regression was used to determine the association of system/provider, sociodemographic, and medical factors with breastfeeding non-initiation in late preterm mother-infant dyads for the year 2009 (n=7,012).

RESULTS

Although LPI breastfeeding initiation in Pennsylvania increased significantly from 2003 (54%) to 2009 (61.8%) (p<0.001), the 2009 prevalence remained well below rates in term infant populations and national standards. The regression model indicated that interactions involving sociodemographic variables, including marital status, age, race/ethnicity, education, parity, Women, Infants and Children Program participation, and smoking status were among the most significant factors associated with LPI breastfeeding non-initiation (p<0.05). The univariate results were similar to those reported in preterm and term populations.

CONCLUSIONS

Our data suggest that certain, unexpected demographic groups in the late preterm population be prioritized for further analysis and possibly greater breastfeeding support. More research is indicated to understand the effect of modifiable psychosocial factors on LPI breastfeeding initiation.

Neurodevelopmental Outcome Among Multiples and Singletons: A Regional Neonatal Intensive Care Unit's Experience in Turkey

Objective: The aim of this study was to compare the neurodevelopmental outcome at 12–18 months’ corrected age between multiples and singleton preterm infants. Methods: We designed a prospective study of preterm infants (≤32 weeks gestation) born and hospitalized in the neonatal intensive care unit between November 2008 and November 2009, whose assessments were performed at 12–18 months’ corrected age. Neurodevelopmental impairment was defined as the presence of any one of the following: moderate or severe cerebral palsy, severe bilateral hearing loss or bilateral blindness, mental developmental index score, or psychomotor developmental index score less than 70. Results were compared for both multiples and singleton infants. Results: One hundred and fifty-nine multiples and 211 singleton infants were assessed at 12–18 months’ corrected age. The neurodevelopmental outcome including all parameters at 12–18 months’ corrected age in multiples was not significantly different from singleton preterm infants. Conclusions: Multiple gestation in preterm infants is not associated with an increased risk of neurodevelopmental impairment at 12–18 months’ corrected age compared with singleton preterm infants. For further information, long term and high participation in neurodevelopmental follow-up and evaluation at pre-school age will be needed.

Multiple gestations: timing of indicated late preterm and early-term births in uncomplicated dichorionic, monochorionic, and monoamniotic twins

In this work we review the indications for late preterm and early-term birth in uncomplicated dichorionic, monochorionic, and monoamniotic twin gestations. Uncomplicated dichorionic twins have optimal outcomes when delivered at 38 weeks' gestation. Monochorionic twins, however, are at greater risk for unexpected stillbirth, and a management plan of late preterm delivery (34-37 weeks) after informed consent is reasonable. Monoamniotic twins are at even greater risk for sudden intrauterine fetal demise, and it is recommended that these expectant mothers be managed by inpatient hospitalization with fetal testing 1-3 times per day and delivery between 32 and 34 weeks' gestation. Recommendations are also provided for the circumstance of single intrauterine fetal demise in a twin gestation.

Follow-up issues with multiples

The rate of multiple pregnancy has increased in developed countries, a finding usually attributed to more widespread use of assisted reproductive technologies. Multiple pregnancies are associated with a greater risk of pregnancy complications, including intrauterine growth restriction of one or more of the fetuses, vascular communications within a shared monochorionic placenta and premature delivery. Surviving infants are at significantly greater risk of developing cerebral palsy due to a combination of a higher proportion of them being preterm or of low birth weight, and complications associated with chorionicity. These infants are also at greater risk for abnormal cognitive development and learning disabilities for the same reasons. Parenting styles and family dynamics may also differ with multiples compared with singletons, which may affect long-term behaviour and development.Thus, infants of multiple pregnancies should receive careful neurodevelopmental follow-up. For larger, lower risk infants, this follow-up may be provided by general paediatricians within the community. However, for infants with birth weights of less than 1000 g or with a complicated antenatal or neonatal course, follow-up should be in a high-risk neonatal follow-up clinic with appropriate multidisciplinary support.

Comparison of short-term outcomes of late preterm singletons and multiple births: an institutional experience

We compare 4 short-term outcomes--namely admission to special care nursery (SCN), length of stay (LOS), age at full feeds (AFF) and respiratory morbidity/need for ventilation--in 1015 late preterm singletons and 366 twins and triplets born at our institution over a 4-year period. Birth weight (BW) and gestational age (GA) rather than plurality of birth determined need for admission to SCN, LOS, AFF, and need for respiratory support. When matched for GA, compared to singletons, twins and triplets needed less admission to SCN and respiratory support at 36 weeks, whereas at 34 weeks, they had longer LOS and took longer to get to full feeds. We conclude that the outcomes of interest are affected by GA and BW rather than plurality.

Twinning on the brain: the effect on neurodevelopmental outcomes

Twinning is currently considered a complex multifactorial trait. Few studies have explored how the unique genetic and environmental influences that create twinning affect phenotypes and outcomes. Previous data has shown that twins account for a significant proportion of preterm and low-birth-weight infants, who are at risk for long-term neurodevelopmental disabilities such as cerebral palsy and cognitive impairment. More recently, it has been postulated that even without these co-morbidities, twinning in and of itself may incur a neurodevelopmental disadvantage even among term newborns. The purpose of this review is to report primarily on neuromotor outcomes of twins compared to singletons. In addition, we describe specific environmental risk factors among twins which are associated with poorer outcomes. Several putative neurodevelopmental modulators are explored, including death of a co-twin, chorionicity, birth weight discordance, and twin-twin transfusion. By teasing out environmental influences that potentially influence neurocognitive outcomes, families can receive more specific counseling and developmental services can be provided to those twins at especially high risk.

MFM/geneticist view on prenatal management of twins

Twin pregnancies are associated with an increase in both fetal and maternal morbidity and mortality. Health care supervision is complex, increasingly requiring care from maternal-fetal medicine specialists. This review discusses optimal twin prenatal management, which includes recognizing increased twin pregnancy risks specific to twin-types; counseling families regarding fetal complications, ranging from prematurity to cerebral palsy; screening for aneuploidy and open neural tube defects; specific twin guidelines for diagnostic testing, including chorionic villus sampling and amniocentesis; and monitoring for maternal complications.

Complicações maternas e ocorrências neonatais associadas às gestações múltiplas resultantes de técnicas de reprodução assistida

A gestação múltipla é a mais freqüente e a mais séria complicação iatrogênica das técnicas de reprodução assistida. O objetivo do estudo foi conhecer as complicações maternas e as ocorrências neonatais associadas às gestações múltiplas resultantes de reprodução assistida em um centro de referência na área de reprodução assistida. Trata-se de uma pesquisa observacional, transversal, descritiva e retrospectiva que foi realizada no Hospital e Maternidade Santa Joana, centro de referência na área de reprodução humana localizado no município de São Paulo, Brasil. A população estudada foi constituída por 131 prontuários de gestantes internadas com patologias clínicas e trabalho de parto, advindas de gestações múltiplas resultantes de técnicas de reprodução assistida. As complicações maternas predominantes foram: o trabalho de parto prematuro (65,5%), a amniorrexe prematura (42%). As ocorrências neonatais mais freqüentes foram as doenças respiratórias (65,1%), a icterícia (38,4%), os distúrbios metabólicos (13%) e as doenças neurológicas (9%).

Twin gestation and neurodevelopmental outcome in extremely low birth weight infants

OBJECTIVE

The purpose of this work was to compare the risk-adjusted incidence of death or neurodevelopmental impairment at 18 to 22 months' corrected age between twin and singleton extremely low birth weight infants. We hypothesized that twin gestation is independently associated with increased risk of death or adverse neurodevelopmental outcomes at 18 to 22 months' corrected age in these infants.

METHODS

We conducted a retrospective study of inborn extremely low birth weight infants admitted to Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network units between 1997 and 2005, who either died or had follow-up data available at 18 to 22 months' corrected age. Neurodevelopmental impairment, the primary outcome variable, was defined as the presence of any 1 of the following: moderate or severe cerebral palsy, severe bilateral hearing loss, bilateral blindness, Bayley Mental Developmental Index or Psychomotor Developmental Index of <70. Death was included with neurodevelopmental impairment as a composite outcome. Results were compared for both twins, twin A, twin B, same-gender twins, unlike-gender twins, and singleton infants. Logistic regression analysis was performed to control for demographic and clinical factors that were different among the groups.

RESULTS

The cohort of infants who either died or were assessed for neurodevelopmental impairment consisted of 7630 singleton infants and 1376 twins. Logistic regression adjusting for clinical and sociodemographic risk factors showed an increased risk of death or neurodevelopmental impairment for twins as a group when compared with the singletons. On analyzing twin A and B separately as well, risk of death or neurodevelopmental impairment was increased in both twin A and twin B.

CONCLUSIONS

Twin gestation in extremely low birth weight infants is associated with an independent increased risk of death or neurodevelopmental impairment at 18 to 22 months' corrected age compared with singleton-gestation infants. Both first- and second-born twins are at increased risk.

The risks for very low birth weight infants from multiple pregnancies

Advances in perinatal and neonatal care in recent years have resulted in dramatic improvements in the rate of intact survival of preterm infants. As a result, neonatologists have focused on the new challenge of bringing about similar advances for the tiniest infants who are born at or near the current limits of viability. Although these tiny infants comprise only a small proportion of all births, the ravages of prematurity make them by far the most challenging group of infants who require our attention in the neonatal intensive care unit.

Contemporary risks of maternal morbidity and adverse outcomes with increasing maternal age and plurality

OBJECTIVE

To evaluate the risks of pregnancy complications and adverse outcomes associated with increasing maternal age and higher plurality.

DESIGN

Population-based, historic cohort study.

SETTING

US birth certificates and infant death certificates.

PATIENT(S)

Live births of > or =20 weeks gestation between 1995-2000: 22,991,306 singleton, 316,696 twin, and 12,193 triplet pregnancies.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Pregnancy-associated hypertension, incompetent cervix, tocolysis, premature rupture of membranes, excessive bleeding at delivery, delivery <29 weeks, and infant death.

RESULT(S)

Compared to singletons, the risks for all adverse outcomes among multiple pregnancies were significantly elevated, and were highest for tocolysis, delivery <29 weeks, and infant mortality. Within pluralities, increasing maternal age was associated with significantly higher risks of pregnancy-associated hypertension, excessive bleeding, and incompetent cervix, but for twin and triplet pregnancies, significantly lower risks for tocolysis (ages > or =40, singleton adjusted odds ratio [AOR] 0.97, twin AOR 0.67, triplet AOR 0.72), delivery <29 weeks (ages > or =40, singleton AOR 1.55, twin AOR 0.72, triplet AOR 0.52), and infant mortality (ages > or =40, singleton AOR 1.34, twin AOR 0.71, triplet AOR 0.42).

CONCLUSION(S)

Older maternal age and higher plurality are each associated with increasing risks for many pregnancy complications, but with significantly lower risks of tocolysis, early preterm birth, and infant mortality.

Association between early postnatal weight loss and death or BPD in small and appropriate for gestational age extremely low-birth-weight infants

OBJECTIVE

To examine the association between weight loss during the first 10 days of life and the incidence of death or bronchopulmonary dysplasia (BPD) in small for gestational age (SGA) and appropriate for gestational age (AGA) extremely low-birth-weight infants.

DESIGN/METHODS

This is a retrospective analysis of a cohort of ELBW (birth weight <1000 g) infants from the NICHD Neonatal Research Network's database. The cohort consisted of 9461 ELBW infants with gestational age of 24-29 weeks, admitted to Network's participating centers during calendar years 1994-2002 and surviving at least 72 h after birth. The cohort was divided into two groups, 1248 SGA (with birth weight below 10th percentile for gestational age) and 8213 AGA (with birth weight between 10th and 90th percentile) infants. We identified infants with or without weight loss during the first 10 days of life, which we termed as 'early postnatal weight loss' (EPWL). Univariate analyses were used to predict whether EPWL was related to the primary outcome, death or BPD, within each birth weight/gestation category (SGA or AGA). BPD and death were also analyzed separately in relation to EPWL. Logistic regression analysis was done to evaluate the risk of death or BPD in SGA and AGA groups, controlling for maternal and neonatal demographic and clinical factors found to be significant by univariate analysis.

RESULTS

SGA ELBW infants had a lower prevalence of EPWL as compared with AGA ELBW infants (81.2 vs 93.7%, respectively, P<0.001). In AGA infants, univariate analysis showed that death or BPD rate was lower in the group of infants with EPWL compared with infants without EPWL (53.4 vs 74.3%, respectively, P<0.001). The BPD (47.2 vs 64%, P<0.001) and death (13.8 vs 32.9%, P<0.001) rate were similarly lower in the EPWL group. The risk-adjusted odds ratios (ORs) showed that EPWL was associated with lower rate of death or BPD (OR 0.47, 95% CI: 0.37-0.60). In SGA infants, on univariate analysis, a similar association between EPWL and outcomes was seen as shown in AGA infants: death or BPD (55.9 vs 75.2%, P<0.001), BPD rate (48.3 vs 62.1%, P=0.002) and rate death (19 vs 40.8%, P<0.001) for those with or without EPWL, respectively. Multiple logistic regression showed that as in AGA ELBW infants, EPWL was associated with lower risk for death or BPD (OR 0.60, 95% CI: 0.41-0.89) among SGA infants.

CONCLUSIONS

SGA infants experienced less EPWL when compared with their AGA counterparts. EPWL was associated with a lower risk of death or BPD in both ELBW AGA and SGA infants. These data suggest that clinicians who consider the association between EPWL and risk of death or BPD should do so independent of gestation/birth weight status.

Incidence and complications of multiple gestation in Canada: proceedings of an expert meeting

This paper reports the proceedings of a consensus meeting on the incidence and complications of multiple gestation in Canada. In addition to background presentations about current and possible future practice in Canada, the expert panel also developed a set of consensus points. The need for infertility to be understood, and funded, as a healthcare problem was emphasized, along with recognition of the emotional impact of infertility. It was agreed that the goal of assisted reproduction treatment is the delivery of a single healthy infant and that even though many positive outcomes have resulted from twin or even triplet pregnancies, the potential risks associated with multiple pregnancy require that every effort be made to achieve this goal. The evidence shows that treatments other than IVF (such as superovulation and clomiphene citrate) contribute significantly to the incidence of multiple pregnancy. There is an urgent need for studies to understand better the usage and application of these other fertility technologies within Canada, as well as the non-financial barriers to treatment. The final consensus of the expert panel was that with adequate funding and good access to treatment, it will be possible to achieve the goal of reducing IVF-related multiple pregnancy rates in Canada by 50%.

A prospective masked observational study of uterine contraction frequency in twins

OBJECTIVE

This study was undertaken to compare uterine contraction frequency in twins versus singletons and to determine if contraction frequency can be an efficient predictor of spontaneous preterm birth in twin gestations.

STUDY DESIGN

Fifty-nine twin and 306 singleton gestations were enrolled between 22 and 24 weeks at 11 centers. Contraction frequency was recorded with a home uterine activity monitor (HUAM) 2 or more times per day on 2 or more days per week until delivery or 36-6/7 weeks. Masked HUAM data were interpreted according to standard protocol. Repeated measures analyses were used to determine whether mean or maximum uterine contraction frequency per hour differed between singleton and twin gestations across gestational age, by time of day, and by delivery before 35 weeks or beyond. Uterine contraction frequency was also evaluated by logistic regression and receiver operator characteristic (ROC) curves as tests to predict spontaneous preterm birth.

RESULTS

There were 34,908 hours of HUAM data recorded by the 306 singleton gestations and 5,427 hours by the 59 women with twins. Uterine contraction frequency was significantly greater in twins (P = .002) compared with singletons, regardless of gestational age. Contraction frequency in twins increased significantly with gestational age and time of day (1600-0359 hours); but was not associated with spontaneous preterm birth. Maximum uterine contraction frequency was associated with preterm birth less than 35 weeks but only in the morning (am) recording (0400-1559) and at the 29- to 30-week gestational age interval. This relationship was modest (odds ratio 1-2) and not consistent across gestational age or between the am and afternoon/evening (pm) monitoring sessions. ROC analysis revealed no contraction frequency that efficiently identified twins who delivered prematurely at any 2-week gestational age interval.

CONCLUSION

Mean uterine contraction frequency was significantly higher for twin gestations than singletons throughout the latter half of pregnancy and between 1600 and 0359 hours but was not higher among twins who delivered less than 35 weeks' gestation. Neither maximum am or pm contraction frequency predicted spontaneous preterm birth less than 35 weeks' gestation in twin pregnancies.

Incidence of infection for preterm twins cared for in cobedding in the neonatal intensive-care unit

OBJECTIVES

To describe the incidence of infection in a group of cobedded preterm twin infants and compare it to the incidence of infection in a cohort of preterm twin infants cared for in the same institution prior to the onset of cobedding.

DESIGN

Retrospective descriptive design.

SETTING

Tertiary, referral neonatal intensive-care unit in the Midwest.

PARTICIPANTS

Preterm twin infants between 23 and 35 weeks gestational age.

METHODS

Data from 1997 to 2001 (cobedding) compared to data from 1992 to 1996 (no cobedding).

MAIN OUTCOME MEASURE

Infection as evidenced by positive blood, cerebrospinal fluid, or urine culture or radiographic evidence of pneumonia or necrotizing enterocolitis.

RESULTS

Independent samples t test found the cobedded and non-cobedded infants to be homogenous in demographic data. A 2-way analysis of variance demonstrated no significant effects for cobedded infants on number of sepsis evaluations or number of positive blood cultures. There was a statistically significant difference for number of positive blood cultures at discharge reflecting the increased number of positive blood cultures in the non-cobedded infants. Finally, there were no statistically significant differences found between cobedded and non-cobedded for the presence of pneumonia or necrotizing enterocolitis.

CONCLUSIONS

Cobedding of preterm twins cared for in the intensive-care nursery was not associated with an increased incidence of infection. Prospective studies are needed on cobedding before a change in practice is implemented.

Multiple gestations and late preterm (near-term) deliveries

Multiple gestations present unique challenges to the modern obstetrician. Many twin and high-order multiple pregnancies are delivered between 34 and 37 weeks' gestation either secondary to preterm labor or obstetrical complications necessitating intervention. Recognizing the increasing prevalence of multiple gestations and the impact of late preterm deliveries in modern practice, this review analyzes the impact of multiple pregnancies on perinatal outcomes, reviews the strategies to prevent preterm labor, and summarizes potential indications for late preterm delivery. In this paper, "late preterm" has been used instead of "near-term," as the former was considered more appropriate to reflect this subgroup of preterm infants in a workshop on this topic held in July 2005, organized by the National Institute of Child Health and Human Development.

Maternal physiology and complications of multiple pregnancy

Approximately 1% to 3% of all pregnancies in the United States are multiple gestations. The vast majority (97-98%) are twin pregnancies. Multiple pregnancies constitute significant risk to both mother and fetuses. Antepartum complications-including preterm labor, preterm premature rupture of the membranes, intrauterine growth restriction, intrauterine fetal demise, gestational diabetes, and preeclampsia-develop in over 80% of multiple pregnancies as compared with approximately 25% of singleton gestations. This article reviews in detail the maternal physiologic adaptations required to support a multiple pregnancy and the maternal complications that develop when these systems fail or are overwhelmed.

Neurodevelopmental outcomes of extremely low birth weight infants <32 weeks' gestation between 1993 and 1998

OBJECTIVE

This study evaluated the impact of changes in perinatal management on neurodevelopmental impairment (NDI) at 18 to 22 months' corrected age of low gestation (22-26 weeks) and higher gestation (27-32 weeks) extremely low birth weight infants (401-1000 g birth weight) who were cared for in the National Institute of Child Health and Human Development Neonatal Research Network during 3 epochs (1993-1994, 1995-1996, and 1997-1998). It was hypothesized that outcomes would improve over the 3 epochs.

METHODS

A multicenter cohort study was conducted of the outcomes of 3785 infants with assessments at 18 to 22 months' corrected age. Regression analyses were completed to evaluate for epoch effects, gestational age effects, and time plus gestational age interaction. Regression analyses were also performed to identify the independent associations of epoch and 4 study perinatal interventions: antenatal steroids (yes, no), high-frequency ventilation (yes, no), number of days to regain birth weight as a marker of nutritional intake, and postnatal steroids for treatment of bronchopulmonary dysplasia (yes, no) with outcomes.

RESULTS

Survival improved for both the low (55%-61%) and higher (82%-86%) gestational age groups during the 3 epochs. Regression analyses indicated that the decreased risk for adverse outcome was significantly lower in epoch 2 compared with epoch 1 with decreased rates of low Bayley Mental Development Index (MDI) and neurodevelopmental impairment (NDI). Antenatal steroids were associated with decreased risk for moderate to severe cerebral palsy (CP) and low Bayley Psychomotor Development Index. High-frequency ventilation was associated with a low Bayley MDI and NDI, and postnatal steroids were associated with moderate to severe CP, any CP, low Bayley MDI, low Bayley Psychomotor Development Index, and increased NDI.

CONCLUSION

Survival of extremely low birth weight infants improved between 1993 and 1998. Although some outcomes remained unchanged, the rates of low Bayley MDI scores and NDI improved. Antenatal steroid administration was the only study intervention associated with improved outcomes.

Nutrition in multiple gestations

Multiple pregnancies represent a state of magnified nutritional requirements, resulting in a greater nutrient drain on maternal resources and an accelerated depletion of nutritional reserves. Maternal weight gain to 20 weeks and between 20 and 28 weeks has the greatest effect on birthweight in twin and triplet pregnancies, particularly among underweight women. Parity, which most likely represents a higher proportion of body fat, has a positive effect on pregnancy outcome, with an average 7 to 10 days longer gestation for multiparous versus nulliparous women. In addition to being the nutrients most often lacking in a woman's diet, calcium, magnesium, and zinc have been identified as having the most potential for reducing pregnancy complications and improving outcomes.

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.

Neonatal morbidity of very low birth weight infants from multiple pregnancies

The epidemic of multiple births has translated into a marked rise in very low birth weight infants, who are at risk for major neonatal morbidity and mortality. Gestational age-adjusted comparisons of outcome between singletons and multiples have shown conflicting results. Comparisons that corrected for relevant confounding variables show that twins and singletons have similar risks for early morbidity and mortality. Very low birth weight triplets may have increased risk for neonatal mortality, however. Second-born very low birth weight twins seem to be at risk for increased respiratory morbidity, even in the era of routine antenatal corticosteroids and postnatal surfactant therapy.

The cost of twin pregnancy: maternal and neonatal factors

OBJECTIVE

The purpose of this study was to evaluate factors affecting birth charges in twin pregnancies.

STUDY DESIGN

Clinical and financial data were obtained on 1486 twin pregnancies delivered between 1995 to 2002 at medical centers in Maryland, Florida, Michigan, and South Carolina. Maternal and neonatal length of stay (LOS) and charges were modeled by gestational age and other risk factors using a general linear model.

RESULTS

Maternal and infant birth admission LOS and charges increased significantly with a decline in gestational age. Maternal LOS and charges were also significantly increased by cesarean delivery and preeclampsia. Newborn LOS and charges increased significantly by monochorionicity and slowed growth between 20 to 28 weeks. For mother and infants, the shortest LOS and lowest birth charges were at 37 to 38 weeks.

CONCLUSION

These findings reflect the substantial maternal and neonatal morbidity associated with twin pregnancies, and demonstrate that 37 to 38 weeks is their optimal gestation.

Factors affecting short-term mortality in very low birth weight infants in Japan

No epidemiological surveys have examined risk factors related to the death of very low birth weight infants (VLBWIs) in Japan. The objectives of this study were to examine the death rate and fatalities related to complications among VLBWIs, and to analyze factors possibly determining the death of VLBWIs. The subjects of this study were 811 VLBWIs admitted to the Neonatal Care Center of Niigata City General Hospital between April 1987 and March 2003. We obtained information on gender, birth weight, gestational age, Apgar scores, single/multiple pregnancy, postnatal transfer, mode of delivery, complications and outcome (alive or deceased) at the time of discharge from medical records. Of the 811 infants, 98 died prior to discharge (12.1%). Logistic regression analysis showed that independent risk factors for death of VLBWIs were male gender (relative risk [RR]: 2.0), low birth weight (RR: 0.56), necrotizing enterocolitis (RR: 58.0), pulmonary hypoplasia (RR: 37.8), chromosomal abnormalities (RR: 36.3), congenital heart diseases (RR: 9.8), persistent fetal circulation (RR: 9.6), neonatal asphyxia (RR: 6.3) and sepsis (RR: 4.4). The risk for death rises 1.8-fold if birth weight decreases by 100 g. A very high risk of perinatal death is associated with necrotizing enterocolitis, pulmonary hypoplasia or chromosomal abnormalities. The risk of death due to congenital heart diseases or neonatal asphyxia is relatively lower, but the incidences of these two disorders are high (8% and 6%, respectively). From the viewpoint of prophylactic treatment aimed at reducing the death rate of VLBWIs, measures to increase birth weight are of primary importance. Furthermore, early treatment and improved perinatal management of congenital heart diseases and neonatal asphyxia are anticipated to reduce the overall death rate of VLBWIs.

Respiratory distress syndrome in twin infants compared with singletons

OBJECTIVE

The purpose of this study was to determine gestational age-specific incidence and risk factors of respiratory distress syndrome (RDS) in twins compared with singletons.

STUDY DESIGN

An analysis of 850,406 singleton and 23,278 twin infants born alive in Finland between 1987 and 2000 was performed. A number of antenatal and perinatal/intranatal factors were evaluated.

RESULTS

At less than 28 weeks of gestation, the incidence of RDS was higher in both first- and second-born twins compared with singletons. At more advanced gestation, first-born twins had a significantly lower incidence of RDS compared with the others. There was no difference in the concordance of RDS between same-sex and opposite-sex twin pairs. Vaginal delivery, female sex, being born first, and being the lighter of the twins protected from RDS.

CONCLUSION

After taking into account gestation, twins are not at higher risk of RDS compared with singletons except at very early gestation. Environmental factors predominate over genetic ones in the predisposition to RDS in twins.

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.

Contributions of infertility treatment to very-low-birth-weight multiple birth infants receiving neonatal intensive care

OBJECTIVE

This study was undertaken to determine proportions of very-low-birth-weight (VLBW) multiple birth infants receiving neonatal intensive care whose mothers received various types of infertility treatment and to evaluate infertility treatment-associated morbidity and mortality.

STUDY DESIGN

Study infants were multiples with birth weight 401 to 1500 g cared for in Cincinnati neonatal intensive care units from January 1996 to December 2000. Data were obtained retrospectively from the National Institute for Child Health and Human Development Neonatal Research Network registry. Use of infertility treatment (in vitro fertilization, injection or oral ovulation, and intrauterine insemination) was determined by maternal interview or chart review. The generalized estimating equation approach to logistic regression was used.

RESULTS

The study included 382 infants of 212 mothers: 201=spontaneous conception (53%), 93=in vitro fertilization (24%), 55=injection (14%), 15=oral (4%), and 18=intrauterine insemination (5%). Neither gestational age nor birth weight differed between groups. More female (58%, P=.003) and white infants (95%, P<.001) resulted from infertility treatment-induced pregnancies than from spontaneous pregnancies. Advancing gestational age significantly decreased odds for all outcomes.

CONCLUSION

Of VLBW multiples receiving neonatal intensive care, 47% are associated with infertility treatment. Infertility treatment does not influence outcomes in VLBW multiples.

Surfactant protein A and B genetic variants in respiratory distress syndrome in singletons and twins

Interactive genetic and environmental factors may influence the differentiation of surfactant and the risk of respiratory distress syndrome (RDS). DNA samples from 441 premature singleton infants and 480 twin or multiple infants were genotyped for surfactant-specific protein (SP)-A1, SP-A2, and SP-B exon 4 polymorphisms and intron 4 size variants in a homogeneous white population. Distributions of the SP-A and SP-B gene variants between RDS and no-RDS infants were determined alone and in combination. SP-A1 allele 6A2 (p = 0.009) and the homozygous genotype 6A2/6A2 (p = 0.003) were overrepresented in RDS of singletons when the SP-B exon 4 genotype was Thr/Thr, and underrepresented in RDS of multiples when the SP-B genotype was Ile/Thr (p = 0.012 for 6A2 and p = 0.03 for 6A2/6A2) or Thr/Thr (p = 0.12 for 6A2 and p = 0.018 for 6A2/6A2, respectively). The SP-A 6A2 allele in the SP-B Thr131 background predisposed the smallest singleton infants to RDS, whereas near-term multiples were protected from RDS. There was a continuous association between fetal mass and risk of RDS, defined by the SP-A and SP-B variants. Labeled lung explants with the Thr/Thr genotype showed proSP-B amino-terminal glycosylation, which was absent in Ile/Ile samples. Genetic and environmental variation may influence intracellular processing of surfactant complex and the susceptibility to RDS.

NICHD neonatal research network: contributions and future challenges

The establishment of the National Institute of Health and Human Development Neonatal Research Network in 1986 was an acknowledgement by the medical community of the need to rigorously perform patient-oriented research in neonates. The limit of viability was being pushed below 26 weeks' gestation by physicians willing to try almost anything to save their extremely low gestational age patients and/or by parents who were willing to accept survival at almost any cost. Too often new treatments or procedures had become standard therapies before efficacy and/or safety had been evaluated. During its first 15 years, the Network has conducted randomized, controlled trials and prospective observational studies focused on such major neonatal issues as brain injury, neuroprotection, late-onset infection, bronchopulmonary dysplasia, severe hypoxic respiratory failure, postnatal growth and nutrition, and long-term neurodevelopmental outcome. This paper reviews the Network's investigative activities during that time, highlights some of the lessons learned in its attempts to identify clinically relevant outcomesthat would change clinical practice, and addresses future challenges.

[Morbidity and mortality of very-low-birth-weight infants as an indicator of the quality of perinatal care]

OBJECTIVE

To compare the clinical outcomes of a cohort of very low birth weight (VLBW) infants who received healthcare in our unit from 1994-2000 with all the variables included in the Vermont-Oxford Network (VON) database.

METHODS

A historical cohort of 417 VLBW live infants born in our center from 1994-2000 was evaluated. The 80 variables of the VON already prospectively included in the unit's database were used and a further 20 variables were added through retrospective review of medical records. The rates of perinatal risk factors, interventions, and causes of morbidity were analyzed and the periods 1994-1997 and 1998-2000 were compared. We also compared these rates with those reported by the VON.

RESULTS

Comparison of the results in both periods showed an increase in the percentage of multiple pregnancies and prenatal corticosteroid exposure, as well as in the early use of surfactant and continuous positive pressure. The incidence of intraventricular hemorrhage decreased, but no differences were observed in other outcomes. Our rates of Cesarean sections and multiple births, as well as the use of prenatal steroids, were higher than those of the VON. The outcomes of infants receiving healthcare in our unit were similar to those of the VON but mortality in infants weighing < 800 g was slightly higher, coinciding with higher rates of late sepsis.

CONCLUSION

Morbidity rates in VLWB infants receiving care in our unit decreased during the period studied and compared favorably with those reported by the VON. Alltogether, our results indicate that the quality of care in our perinatal center is good. General use of this methodology would permit comparison of outcomes and quality of care across regions and nations, as well as across Europe, in a recently established network (EuroNeoNet.com).

Cerebral morbidity in preterm twins

BACKGROUND

Whether twins are more prone to increased neonatal morbidity than singletons remains controversial. It was the aim of this study to define the special risks of preterm twins with an emphasis on cerebral morbidity.

METHODS

A retrospective chart review was carried out of all consecutively born twins (n = 230) and the corresponding sets of singletons of a single level-III neonatal intensive care unit. The subjects had a gestational age between 24 and 37 weeks, and were born in 1990-98.

RESULTS

Twin pregnancies were more often complicated by preterm contractions (odds ratio (OR) 4.03 (95% confidence interval (CI) 2.39, 6.78)) whereas gestosis was significantly less (OR 0.14 (95% CI 0.05, 0.41)). Grades III and IV intracranial bleeding occurred significantly more often in twins compared to singletons (OR 3.75 (95% CI 1.65, 8.97)), with infants of less than 32 weeks' gestational age being predominantly affected (OR 3.31 (95% CI 1.33, 8.29)). Infants of less than 32 weeks' gestational age developed respiratory distress syndrome more often than the corresponding singletons (OR 1.93 (95% CI 1.15, 3.25)). There were no differences in all observed items between the first- and second-born twins.

CONCLUSION

Twins of less than 37 weeks' gestational age were significantly more often affected by high-grade intraventricular hemorrhage irrespective of birth order. Periventricular leukomalacia occurred twice as often as in singletons. There were no differences with respect to mortality and further morbidity except for respiratory distress syndrome in preterm twins of less than 32 weeks' gestational age.

Neonatal outcome of triplet versus twin and singleton pregnancies: a matched case control study

OBJECTIVE

To determine the neonatal outcome of triplet gestations versus that of singletons and twins matched for gestational age.

STUDY DESIGN

All live born triplet gestations delivered between 1 April 1993 and 31 March 2000 were compared to an age matched control group consisting of live born twins and singletons. The neonatal outcome of 116 sets of triplets was compared to that of 116 sets of twins and 116 singletons.

RESULTS

During a 7-year period 116 sets of triplet pregnancies were reviewed. Of 116 sets of live born triplets (348 newborns), 70.67% triplets were born between 33- and 36-week gestation, 28.44% between 28 and 32 weeks and 0.86% less than 28 weeks. Triplets were smaller in weight than singletons but not twins. Apgar score, use of prenatal steroid and sex ratio were similar in the three groups. Incidence of respiratory distress syndrome (RDS), use of surfactant, infants requiring intubation, pneumothorax, patent ductus arteriosus, sepsis, intraventricular hemorrhage, periventricular leucomalacia, retinopathy of prematurity, necrotizing enterocolitis, gastroesophageal reflux and jaundice requiring phototherapy were not statistically different among the three groups. Incidence of major and minor congenital anomalies, percent neonatal intensive care unit (NICU) admissions, and mean duration of NICU stay were also similar. There was no influence of birth order on neonatal outcome of triplet pregnancy and outcome did not significantly change over 7 years of the study period.

CONCLUSIONS

Triplets have a similar outcome to twins and singletons when matched for gestational age. Since outcome is dependent on gestational age, the closer the gestational age is to term the better is the outcome.