Accounting for multiple births in neonatal and perinatal trials: systematic review and case study

Neonatal intermittent hypoxemia events are associated with later systemic hypertension

BACKGROUND

Approximately 5% of very premature infants delivered at less than 30 weeks' gestation have systemic hypertension. In adult human and animal models, intermittent hypoxemia events are associated with systemic hypertension. In neonates, intermittent hypoxemia events are associated with adverse outcomes, but it is unknown if they are a risk factor for hypertension. We hypothesize that early intermittent hypoxemia events in very preterm neonates are associated with systemic hypertension at 34-36 weeks' postmenstrual age.

METHODS

Secondary analysis of a single-center cohort study of 164 infants, <31 weeks' gestational age. Intermittent hypoxemia events were continuously recorded during the first 21 days of age.

RESULTS

There was a significant association between the number of intermittent hypoxemia events (per 100) and systemic hypertension (OR (95% CI) = 1.08 (1.01-1.15)), and both the number of intermittent hypoxemia events (per 100 β (95% CI) = 0.22 (0.10-0.34)) and percent of time with hypoxemia (β (95% CI) = 0.10 (0.01-0.19)) and systolic blood pressure at 34-36 weeks' postmenstrual age.

CONCLUSION

This study demonstrated a higher incidence of early intermittent hypoxemia events in preterm infants with hypertension. Decreasing intermittent hypoxemia during this critical period may reduce incidence of later vascular stress in this population.

IMPACT

Intermittent hypoxemia events are very common in premature infants and increased frequency of intermittent hypoxemia events is associated with morbidity. Intermittent hypoxemia events in adult human as well as adult and neonatal animal models are associated with systemic hypertension. This study demonstrated an association between early intermittent hypoxemia events and systemic hypertension in very preterm neonates, adding to the body of literature of possible morbidities caused by intermittent hypoxemia events. This study addresses the common, though under-recognized, issue of neonatal hypertension, and suggests increased intermittent hypoxemia events may be contributory.

Complete shielding of multivitamins to reduce toxic peroxides in the parenteral nutrition (C-SMART-PN): A randomized controlled pilot study

BACKGROUND

When exposed to ambient light, parenteral nutrition (PN) contamination with peroxides almost doubles, which increases oxidative stress in preterm infants, contributing to the development of bronchopulmonary dysplasia. The American Society for Parenteral and Enteral Nutrition (ASPEN) recommends complete PN photoprotection to reduce peroxide contamination and optimize its integrity but acknowledges the challenges of its implementation. In this study, a novel photoprotection procedure was tested for its effectiveness in reducing peroxide load and limiting ascorbic acid degradation, and for its feasibility and effectiveness in reducing urinary peroxide levels in preterm infants.

METHODS

In vitro evaluation included neonatal lipid injectable emulsion-free PN admixtures prepared and infused according to current practice or the suggested photoprotection procedure through separation and complete shielding of intravenous multivitamin preparation from compounding to administration through photoprotected infusion sets. In vivo evaluation included a single-center randomized controlled pilot study of extremely preterm infants receiving PN according to current practice or the suggested photoprotection procedure.

RESULTS

In vitro, photoprotection allowed a 44% decrease in peroxide generation (P < 0.001) and reduced by half ascorbic acid degradation in PN admixtures (P < 0.001). In vivo, 28 infants completed the study. Baseline urinary peroxide levels were similar in both groups before PN initiation, and the suggested photoprotection procedure resulted in a significant decrease in urinary peroxide levels over the first week of life (P < 0.05).

CONCLUSION

The suggested procedure appears feasible and effective in reducing peroxide contamination and optimizing PN integrity, representing a step toward integrating complete photoprotection of PN as the standard of care in preterm infants.

We should do better in accounting for multiple births in neonatal randomised trials: a methodological systematic review

OBJECTIVE

To conduct a methodological systematic review of multicentre trials of premature infants to (1) determine if and how multiple births have been considered in the design, analysis and reporting of recent trials and (2) assess whether there has been an improvement since the last review was conducted 10 years ago.

DESIGN

A systematic search was conducted in PubMed on 28 June 2023 for articles published between June 2018 and June 2023. Articles were eligible for inclusion if they were a multicentre randomised trial of infants born preterm and reported the results of a primary outcome that was measured on an infant or could be attributed to an infant.

RESULTS

We reviewed 62/74 trials (80%), after determining it was unclear if multiple births were present in the other 20%. 87% of trials (54/62) did not account for multiple births in their sample size calculations and 48% (30/62) did not account for clustering due to multiple births in their analyses. Problems were not limited to lower-ranked journals. No trials reported the intraclass correlation coefficient for any outcomes, indicating the degree of clustering present.

CONCLUSIONS

Persistent problems remain with the design and analysis of multicentre trials of premature infants due to ignoring the complexity that comes with the inclusion of multiple births, despite methods available to address this. Trialists should consider the impact of multiple births in their trial design and analysis. Readers of neonatal trials should be aware of these issues, particularly those who peer review papers.

Performance of mixed effects models and generalized estimating equations for continuous outcomes in partially clustered trials including both independent and paired data

Many clinical trials involve partially clustered data, where some observations belong to a cluster and others can be considered independent. For example, neonatal trials may include infants from single or multiple births. Sample size and analysis methods for these trials have received limited attention. A simulation study was conducted to (1) assess whether existing power formulas based on generalized estimating equations (GEEs) provide an adequate approximation to the power achieved by mixed effects models, and (2) compare the performance of mixed models vs GEEs in estimating the effect of treatment on a continuous outcome. We considered clusters that exist prior to randomization with a maximum cluster size of 2, three methods of randomizing the clustered observations, and simulated datasets with uninformative cluster size and the sample size required to achieve 80% power according to GEE-based formulas with an independence or exchangeable working correlation structure. The empirical power of the mixed model approach was close to the nominal level when sample size was calculated using the exchangeable GEE formula, but was often too high when the sample size was based on the independence GEE formula. The independence GEE always converged and performed well in all scenarios. Performance of the exchangeable GEE and mixed model was also acceptable under cluster randomization, though under-coverage and inflated type I error rates could occur with other methods of randomization. Analysis of partially clustered trials using GEEs with an independence working correlation structure may be preferred to avoid the limitations of mixed models and exchangeable GEEs.

Partially clustered designs for clinical trials: Unifying existing designs using consistent terminology

INTRODUCTION

Clinical trial designs based on the assumption of independent observations are well established. Clustered clinical trial designs, where all observational units belong to a cluster and outcomes within clusters are expected to be correlated, have also received considerable attention. However, many clinical trials involve partially clustered data, where only some observational units belong to a cluster. Examples of such trials occur in neonatology, where participants include infants from both singleton and multiple births, and ophthalmology, where one or two eyes per participant may need treatment. Partial clustering can also arise in trials of group-based treatments (e.g. group education or counselling sessions) or treatments administered individually by a discrete number of health care professionals (e.g. surgeons or physical therapists), when this is compared to an unclustered control arm. Trials involving partially clustered data have received limited attention in the literature and the current lack of standardised terminology may be hampering the development and dissemination of methods for designing and analysing these trials.

METHODS AND EXAMPLES

In this article, we present an overarching definition of partially clustered trials, bringing together several existing trial designs including those for group-based treatments, clustering due to facilitator effects and the re-randomisation design. We define and describe four types of partially clustered trial designs, characterised by whether the clustering occurs pre-randomisation or post-randomisation and, in the case of pre-randomisation clustering, by the method of randomisation that is used for the clustered observations (individual randomisation, cluster randomisation or balanced randomisation within clusters). Real life examples are provided to highlight the occurrence of partially clustered trials across a variety of fields. To assess how partially clustered trials are currently reported, we review published reports of partially clustered trials.

DISCUSSION

Our findings demonstrate that the description of these trials is often incomplete and the terminology used to describe the trial designs is inconsistent, restricting the ability to identify these trials in the literature. By adopting the definitions and terminology presented in this article, the reporting of partially clustered trials can be substantially improved, and we present several recommendations for reporting these trial designs in practice. Greater awareness of partially clustered trials will facilitate more methodological research into their design and analysis, ultimately improving the quality of these trials.

Immunogenicity of a liquid hexavalent DTaP-IPV-HB-PRP∼T vaccine after primary and booster vaccination of term and preterm infants born to women vaccinated with Tdap during pregnancy

BACKGROUND

Vaccination during pregnancy with tetanus, diphtheria, acellular pertussis (aP) (Tdap) antigens is important for early protection of newborn infants against pertussis, particularly for preterm infants. This study evaluated the effect of Tdap vaccination during pregnancy on the immunogenicity of a diphtheria (D), tetanus (T), aP, inactivated poliovirus (IPV), hepatitis B (HB), and Haemophilus influenzae type b (PRP ∼ T) vaccine in term and preterm populations.

METHODS

A prospective, observational study (NCT02511327) recruited women and their infants based on delivery (term or preterm) and vaccination status (vaccinated with a Tdap vaccine [Boostrix™, GlaxoSmithKline] during pregnancy or not vaccinated in the last 5 years). All infants received licensed DTaP-IPV-HB-PRP ∼ T (Hexyon™, Sanofi) (8, 12, 16 week primary series and booster at 13 months of age [preterm infants] or 15 months of age [term infants]). Immunogenicity was evaluated using validated assays. Data were pooled into term (N = 127) and preterm infants (N = 105), and infants of women who received a Tdap vaccine during pregnancy (N = 199) or not (N = 33).

RESULTS

Before primary vaccination, antibody levels were higher for term than preterm infants for anti-D, anti-polio 1, 2, 3, anti-PT, anti-FHA, and anti-PRP, and similar for anti-HBs and anti-T. At this time, infants of Tdap-vaccinated women had higher anti-D, anti-T, anti-PT, anti-FHA, and anti-PRP antibody levels than infants of Tdap-unvaccinated women; anti-HBs and anti-polio antibody levels were similar in both groups. Post-primary, pre-booster, and post-booster, there were only small differences in seroprotection rates (anti-D, anti-T, anti-polio 1, 2, 3, anti-HBs, anti-PRP) and seroconversion rates (anti-PT, anti-FHA), except for anti-HBs ≥ 10 mIU/mL and anti-PRP ≥ 0.15 µg/mL post-primary vaccination (higher for term [98.31 % and 90.91 %, respectively] versus preterm infants [89.80 % and 79.41 %, respectively]).

CONCLUSIONS

These data support the use of DTaP-IPV-HB-PRP ∼ T vaccine for primary and booster vaccination in term and preterm born infants and in infants born to Tdap-vaccinated or Tdap-unvaccinated women.

Very preterm birth and trajectories of domain-specific self-concept from childhood into adulthood

Self-concept refers to individuals' perceptions of themselves in specific domains and is closely related with their overall self-esteem. Lower self-esteem has been reported in those born preterm (<37 weeks gestation), but the development of self-concept has not been studied in this population. This study investigates whether differences in trajectories of domain-specific self-concepts are explained by premature birth or other risk factors, using the Bavarian Longitudinal Study (N = 460), a population-based study of very preterm (VP; <32 weeks gestation)/very low birth weight (VLBW; <1500 g) cohort and term-born controls. Trajectories of body and social self-concept from 6 to 26 years of age were estimated using latent class growth analysis. Regression models examined the effects of VP/VLBW and other individual, social, and family factors. Two trajectories - one stable and one decreasing - were identified for both self-concepts. VP/VLBW birth was associated with decreasing self-concept in both domains, although the effect of VP/VLBW on social self-concept was weakened in the adjusted analysis. Furthermore, mediated pathways were found from VP/VLBW to decreasing social self-concept via chronic bullying (β = 0.05, 95% CI [0.002, 0.12]) and motor impairments (β = 0.04, 95% CI [0.01, 0.07]), suggesting that negative self-concept in the VP/VLBW population is partially modifiable through improving peer relationships and motor impairments in childhood.

Effect of Invasive Mechanical Ventilation at Birth on Lung Function Later in Childhood

BACKGROUND

Despite recent neonatal care improvements, mechanical ventilation still remains a major cause of lung injury and inflammation. There is growing literature on short- and long-term respiratory outcomes in infants born prematurely in the post-surfactant era, but the exclusive role of mechanical ventilation at birth in lung function impairment is still unclear. The aim of this study was to assess the effect of neonatal mechanical ventilation on lung function parameters in children born ≤ 32 weeks of gestational age at 11 years of age.

MATERIALS AND METHODS

In total, 55 ex-preterm children born between January 1, 2006 and December 31, 2007 were enrolled at 11 years of age. Neonatal information was obtained from medical records. Information about family and personal clinical history was collected by questionnaires. At 11 years of age, we measured spirometry parameters, lung volumes, diffusing lung capacity, and fractional exhaled nitric oxide. In addition, an allergy evaluation by skin prick test and eosinophil blood count were performed. A multivariable linear or logistic regression analysis was performed to examine the associations of mechanical ventilation with respiratory outcomes, adjusting for confounders (maternal smoking during pregnancy, gestational age, surfactant replacement therapy, and BMI).

RESULTS

No difference in lung function evaluation between ventilated and unventilated children were found. No association was also found between mechanical ventilation with lung function parameters.

CONCLUSION

Mechanical ventilation for a short period at birth in preterm children was not associated with lung function impairment at 11 years of age in our study sample. It remains to define if ventilation may have a short-term effect on lung function, not evident at 11 years of age.

Systemic Inflammation in the First 2 Weeks after Birth as a Determinant of Physical Growth Outcomes in Hospitalized Infants with Extremely Low Gestational Age

OBJECTIVE

To examine associations of systemic inflammation with growth outcomes at neonatal intensive care unit discharge or transfer among infants with extremely low gestational ages.

STUDY DESIGN

We studied 850 infants at born at 23-27 weeks of gestation. We defined inflammatory protein elevation as the highest quartile of C-reactive protein (CRP), Interleukin (IL)-6, tumor necrosis factor-∝, or IL-8 on postnatal days 1, 7, and 14. We compared z-scores of weight, length, and head circumference at neonatal intensive care unit discharge or transfer between infants with vs without inflammatory protein elevation, adjusting in linear regression for birth size z-score, sex, gestational age, diet, comorbidities, medications, and length of hospitalization.

RESULTS

The mean gestational age was 25 weeks (range, 23-27 weeks) and birth weight z-score 0.14 (range, -2.73 to 3.28). Infants with a high CRP on day 7 had lower weights at discharge or transfer (-0.17 z-score; 95% CI, -0.27 to -0.06) than infants without CRP elevation, with similar results on day 14. Infants with CRP elevation on day 14 were also shorter (-0.21 length z-scores; 95% CI, -0.38 to -0.04), and had smaller head circumferences (-0.18 z-scores; 95% CI, -0.33 to -0.04) at discharge or transfer. IL-6 elevation on day 14 was associated with lower weight (-0.12; 95% CI, -0.22 to -0.02); IL-6 elevation on day 7 was associated with shorter length (-0.27; 95% CI, -0.43 to -0.12). Tumor necrosis factor-∝ and IL-8 elevation on day 14 were associated with a lower weight at discharge or transfer.

CONCLUSIONS

Postnatal systemic inflammation may contribute to impaired nutrient accretion during a critical period in development in infants with extremely low gestational ages.

Associations between Neonatal Magnetic Resonance Imaging and Short- and Long-Term Neurodevelopmental Outcomes in a Longitudinal Cohort of Very Preterm Children

OBJECTIVE

To assess associations between neonatal brain injury assessed by magnetic resonance imaging and cognitive, motor, and behavioral outcomes at 2 and 10 years of age, in a longitudinal cohort of children born very preterm.

STUDY DESIGN

There were 112 children born at <32 weeks of gestation who participated in a longitudinal prospective study on brain injury and neurodevelopmental outcome. Using the Kidokoro score, neonatal brain injury and altered brain growth in white matter, cortical and deep gray matter, and the cerebellum were assessed. Cognitive, motor, and behavioral outcomes were assessed during follow-up visits at both 2 (corrected) and 10 years of age.

RESULTS

After adjusting for perinatal factors and level of maternal education, the global brain abnormality score was associated with cognition (B = -1.306; P = .005), motor skills (B = -3.176; P < .001), and behavior (B = 0.666; P = .005) at 2 years of age, but was not associated with cognition at 10 years of age. In the subgroup of children with a moderate-severe global brain abnormality score, magnetic resonance imaging was independently associated with cognitive impairment at 10 years of age. For children with milder forms of brain injury, only birth weight and level of maternal education were associated with cognitive outcomes.

CONCLUSIONS

Neonatal brain injury, assessed by a standardized scoring system, was associated with short-term neurodevelopmental outcomes, but only with motor skills and behavior in childhood. Environmental factors, such as level of maternal education, become more important for cognitive development as children grow older, especially for children with relatively mild neonatal brain injury.

Perinatal outcomes in singleton live births after fresh blastocyst-stage embryo transfer: a retrospective analysis of 67 147 IVF/ICSI cycles

STUDY QUESTION

Are perinatal outcomes different between singleton live births conceived from fresh blastocyst transfer and those following the transfer of fresh cleavage-stage embryos?

SUMMARY ANSWER

Fresh blastocyst transfer does not increase risks of preterm birth (PTB), low/high birth weight or congenital anomaly and does not alter the sex ratio at birth or prejudice the chance of having a healthy baby.

WHAT IS KNOWN ALREADY

Extended embryo culture is currently considered the best option for embryo selection, but concerns have been raised about increased risks of preterm delivery and large-for-gestational-age (LGA) babies.

STUDY DESIGN, SIZE, DURATION

We conducted a retrospective cohort study based on data from the Human Fertilisation and Embryology Authority (HFEA) anonymised and cycle-based dataset in the UK between 1999 and 2011.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Baseline characteristics were compared between in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) blastocyst-stage and cleavage-stage embryo transfer cycles using the χ2 test for categorical/dichotomised covariates and the Mann-Whitney test for continuous covariates. Statistical significance was set at <0.005. Poisson regression and multinomial logistic regression were used to establish relationships between perinatal outcomes and blastocyst-stage embryo transfer or cleavage-stage embryo transfer. Risk ratios (RRs), adjusted risk ratios (aRRs) and their 99.5% confidence intervals (CIs) were calculated as a measure of strength of associations. Results were adjusted for clinically relevant covariates. A sub-group analysis included women undergoing their first IVF/ICSI treatment. The level of significance was set at <0.05, and 95% CIs were calculated in the sub-group analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Of a total of 67 147 IVF/ICSI cycles, 11 152 involved blastocyst-stage embryo(s) and 55 995 involved cleavage-stage embryo(s). The two groups were comparable with regards to the risk of PTB (aRR, 1.00; 99.5% CI, 0.79-1.25), very-preterm birth (VPTB) (aRR, 1.00; 99.5% CI, 0.63-1.54), very-low birth weight (VLBW) (aRR, 0.84; 99.5% CI, 0.53-1.34), low birth weight (LBW) (aRR, 0.92; 99.5% CI, 0.73-1.16), high birth weight (HBW) (aRR, 0.94; 99.5% CI, 0.75-1.18) and very-high birth weight (VHBW) (aRR, 1.05; 99.5% CI, 0.66-1.65). The risk of congenital anomaly was 16% higher in the blastocyst-stage group than in the cleavage-stage group, but this was not statistically significant (aRR, 1.16; 99.5% CI, 0.90-1.49). The chance of having a healthy baby (born at term, with a normal birth weight and no congenital anomalies) was not altered by extended culture (aRR, 1.00; 99.5% CI, 0.93-1.07). Extended culture was associated with a marginal increase in the chance having a male baby in the main cycle-based analysis (aRR, 1.04; 99.5% CI, 1.01-1.09) but not in the sub-group analysis of women undergoing their first cycle of treatment (aRR, 1.04; 95% CI, 1.00-1.08). In the sub-group analysis, the risk of congenital anomalies was significantly higher after blastocyst-stage embryo transfer (aRR, 1.42; 95% CI, 1.12-1.81).

LIMITATIONS, REASONS FOR CAUTION

This study is limited by the use of observational data and inability to adjust for key confounders, such as maternal smoking status and body mass index (BMI), which were not recorded in the HFEA dataset. As the main analysis was cycle-based and we were unable to link cycles within women undergoing more than one IVF/ICSI cycle, we undertook a sub-group analysis on women undergoing their first treatment cycle.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings should reassure women undergoing blastocyst-stage embryo transfer. For the first time, we have shown that babies born after blastocyst transfer have a similar chance of being healthy as those born after cleavage-stage embryos transfer.

STUDY FUNDING/COMPETING INTEREST(S)

The research activity of Dr Nicola Marconi was funded by the scholarship 'A. Griffini-J. Miglierina', Fondazione Comunitaria del Varesotto, Provincia di Varese, Italy. The authors do not have any competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Perinatal epidemiology: Issues, challenges, and potential solutions

Perinatal epidemiology research is concerned with identifying the effects of events during pregnancy on pregnancy outcomes that include maternal, fetal, and neonatal health outcomes. Randomized trials in perinatal research face many challenges, including randomization difficulties, ethical considerations, and inadequate statistical power due to the small number of subjects eligible for participation. For these reasons, most epidemiological studies conducted in this research field are observational and include different types of bias. This review describes the key methodological difficulties in the design and analysis of randomized and observational studies in perinatal epidemiology, and provides potential corrective approaches.

The Value of Twins for Health and Medical Research: A Third of a Century of Progress

In 1984, Hrubec and Robinette published what was arguably the first review of the role of twins in medical research. The authors acknowledged a growing distinction between two categories of twin studies: those aimed at assessing genetic contributions to disease and those aimed at assessing environmental contributions while controlling for genetic variation. They concluded with a brief section on recently founded twin registries that had begun to provide unprecedented access to twins for medical research. Here we offer an overview of the twin research that, in our estimation, best represents the field has progress since 1984. We start by summarizing what we know about twinning. We then focus on the value of twin study designs to differentiate between genetic and environmental influences on health and on emerging applications of twins in multiple areas of medical research. We finish by describing how twin registries and networks are accelerating twin research worldwide.

Classroom-evaluated school performance at nine years of age after very preterm birth

OBJECTIVE

To determine classroom-evaluated school performance nine years after preterm birth, predicted by perinatal risk factors and neonatal brain abnormalities.

STUDY DESIGN

Children were recruited from a consecutive cohort of 113 preterm infants (<32 weeks' gestation), participating in a longitudinal prospective study, investigating brain injury and neurodevelopmental outcome. Data on perinatal risk factors, presence of brain injury at term-equivalent age, and maternal education were collected. Information on school performance included enrollment in special (primary) education, grade repetition and school results from the nationwide standardized Dutch Pupil Monitoring System regarding reading comprehension, spelling, and mathematics.

RESULTS

Information on school enrollment was available for 87 children (77%), of whom 7 (8%) were in special primary education and 19 (22%) repeated a grade. This was significantly higher compared to national rates (p ≤ .05). Results on school performance were available for 74 children (65%) and showed clearly below average scores in reading comprehension (p = .006), spelling (p = .014) and mathematics (p < .001). Univariate analysis showed that lower performance in reading comprehension was predicted by male sex and low maternal education; spelling by male sex; and mathematics by Bronchopulmonary Dysplasia, white matter injury and maternal education. In a multivariate model, male sex and maternal education were predictive for reading comprehension and white matter injury for mathematics.

CONCLUSION

Preterm born children more often need special primary education and have higher grade repeat rates. They perform poorer on reading comprehension, spelling and mathematics. Regular follow-up remains important for preterm born children during school age.

Massachusetts' Parental Consent Law and Procedural Timing Among Adolescents Undergoing Abortion

OBJECTIVE

To describe individual-level delay in obtaining abortion associated with use of the Massachusetts judicial bypass system, which legal minors (aged 17 years or younger) use to obtain abortion without consent of a parent or legal guardian in the setting of Massachusetts' parental consent law for abortion.

METHODS

We conducted a retrospective cohort study of 2,026 abortions among minors at a large, statewide network of abortion clinics between 2010 and 2016. Delay was defined as the number of calendar days between the minor's first call to the clinic to schedule an abortion, and the day the abortion was received.

RESULTS

In the study population, 1,559 (77%) abortions were obtained with parental consent and 467 (23%) using judicial bypass. Abortions after judicial bypass were more common among minors identifying as Hispanic, non-Hispanic black, or other race, those of low socioeconomic status (as indicated by having Medicaid insurance) and those with a prior birth or prior abortion (all P<.05). Minors with parental consent received their abortion a mean of 8.6 days after initial contact, compared with 14.8 days for minors with judicial bypass, for an unadjusted difference of 6.1 days. In multivariable linear regression modeling adjusting for demographic differences between groups, this difference persisted: minors who obtained abortions after judicial bypass had a significantly greater delay compared with those with parental consent (adjusted mean difference = 5.2 days; 95% CI 4.3 to 6.2). Using multivariable logistic regression modeling, minors with judicial bypass also had higher odds of becoming ineligible for medication abortion between the day of first call and the day of procedure (adjusted odds ratio 1.57; 95% CI 1.09 to 2.26).

CONCLUSION

Massachusetts' parental consent law for abortion is associated with delay among minors and thereby may constrain the clinical options available to them.

Patterned frequency-modulated oral stimulation in preterm infants: A multicenter randomized controlled trial

Objective

To evaluate the effect of patterned, frequency-modulated oro-somatosensory stimulation on time to full oral feeds in preterm infants born 26–30 weeks gestation.

Study design

This is a multicenter randomized controlled trial. The experimental group (n = 109) received patterned, frequency-modulated oral stimulation via the NTrainer system through a pulsatile pacifier and the control group (n = 101) received a non-pulsatile pacifier. Intent-to-treat analysis (n = 210) was performed to compare the experimental and control groups and the outcomes were analyzed using generalized estimating equations. Time-to-event analyses for time to reach full oral feeds and length of hospital stay were conducted using Cox proportional hazards models.

Results

The experimental group had reduction in time to full oral feeds compared to the control group (-4.1 days, HR 1.37 (1.03, 1.82) p = 0.03). In the 29–30 weeks subgroup, infants in the experimental group had a significant reduction in time to discharge (-10 days, HR 1.87 (1.23, 2.84) p < 0.01). This difference was not observed in the 26–28 weeks subgroup. There was no difference in growth, mortality or morbidities between the two groups.

Conclusions

Patterned, frequency-modulated oro-somatosensory stimulation improves feeding development in premature infants and reduces their length of hospitalization.

Trial registration

ClinicalTrials.gov NCT01158391

Evaluating the efficacy of Seattle-PAP for the respiratory support of premature neonates: study protocol for a randomized controlled trial

BACKGROUND

At birth, the majority of neonates born at <30 weeks of gestation require respiratory support to facilitate transition and ensure adequate gas exchange. Although the optimal approach to the initial respiratory management is uncertain, the American Academy of Pediatrics endorses noninvasive respiratory support with nasal continuous positive airway pressure (nCPAP) for premature neonates with respiratory insufficiency. Despite evidence for its use, nCPAP failure, requiring intubation and mechanical ventilation, is common. Recently, investigators have described a novel method to deliver bubble nCPAP, termed Seattle-PAP. While preclinical and pilot studies are encouraging regarding the potential value of Seattle-PAP, a large trial is needed to compare Seattle-PAP directly with the current standard of care for bubble nCPAP (Fisher & Paykel CPAP or FP-CPAP).

METHODS/DESIGN

We designed a multicenter, non-blinded, randomized controlled trial that will enroll 230 premature infants (22^0/7 to 29^6/7 weeks of gestation). Infants will be randomized to receive Seattle-PAP or FP-CPAP. The primary outcome is respiratory failure requiring intubation and mechanical ventilation. Secondary outcomes include measures of short- and long-term respiratory morbidity and cost-effectiveness.

DISCUSSION

This trial will assess whether Seattle-PAP is more efficacious and cost-effective than FP-CPAP in real-world practice among premature neonates.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03085329 . Registered on 21 March 2017.

Sudden vs Pressure Wean From Nasal Continuous Positive Airway Pressure in Infants Born Before 32 Weeks of Gestation: A Randomized Clinical Trial

IMPORTANCE

Nasal continuous positive airway pressure (nCPAP) is a well-established treatment of respiratory distress syndrome in preterm infants. Suboptimal weaning from nCPAP may be associated with lung injury, pulmonary morbidity, and infant weight gain. To our knowledge, the best weaning strategy from nCPAP is unknown.

OBJECTIVE

To compare the effect of sudden wean and pressure wean from nCPAP in very preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

A randomized, clinical, open-label, multicenter trial was conducted at 6 neonatal intensive care units in Denmark from September 2012 to December 2016 and included infants born before 32 weeks of gestation.

INTERVENTIONS

Sudden wean with discontinuation of nCPAP without a prior reduction in pressure. Pressure wean with gradual pressure reduction prior to the discontinuation of nCPAP.

MAIN OUTCOME AND MEASURES

The primary outcome was weight gain velocity from randomization to postmenstrual age 40 weeks. Secondary outcomes included other measures of growth, nCPAP and the duration of oxygen supplementation, postmenstrual age at successful wean and at discharge, successful wean at the first attempt, the number of attempts to wean, and the length of the hospital stay. Prespecified subgroup analyses by gestational age were performed.

RESULTS

Of the 372 randomized infants, 185 (49.7%) were randomized to sudden wean and 187 infants (50.3%) to pressure wean. A total of 177 infants in both groups completed the trial (median gestational age for sudden and pressure wean, 30 weeks [interquartile range, 29-31]; male: sudden wean, 89 [50%]; pressure wean, 96 [54%]). There was no difference in mean [SD] weight gain velocity from randomization to 40 weeks postmenstrual age between the 2 groups (22 [6] g/kg/day). No difference was found in any of the secondary outcomes. More infants born before 28 weeks of gestation were successfully weaned from nCPAP during the first attempt in the pressure wean group compared with the sudden wean group (risk difference, 31%; 95% CI, 13%-50%), but there was no difference in the duration of nCPAP and oxygen supplementation.

CONCLUSIONS AND RELEVANCE

Overall, we found no difference in weight gain velocity or any of the secondary outcomes between very preterm infants who were randomized to sudden wean or pressure wean from nCPAP. However, among infants born before 28 weeks' gestation, infants from the pressure wean group were more often successfully weaned during the first attempt without a longer total duration of nCPAP treatment.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01721629.

Accounting for twin births in sample size calculations for randomised trials

BACKGROUND

Including twins in randomised trials leads to non-independence or clustering in the data. Clustering has important implications for sample size calculations, yet few trials take this into account. Estimates of the intracluster correlation coefficient (ICC), or the correlation between outcomes of twins, are needed to assist with sample size planning. Our aims were to provide ICC estimates for infant outcomes, describe the information that must be specified in order to account for clustering due to twins in sample size calculations, and develop a simple tool for performing sample size calculations for trials including twins.

METHODS

ICCs were estimated for infant outcomes collected in four randomised trials that included twins. The information required to account for clustering due to twins in sample size calculations is described. A tool that calculates the sample size based on this information was developed in Microsoft Excel and in R as a Shiny web app.

RESULTS

ICC estimates ranged between -0.12, indicating a weak negative relationship, and 0.98, indicating a strong positive relationship between outcomes of twins. Example calculations illustrate how the ICC estimates and sample size calculator can be used to determine the target sample size for trials including twins.

CONCLUSIONS

Clustering among outcomes measured on twins should be taken into account in sample size calculations to obtain the desired power. Our ICC estimates and sample size calculator will be useful for designing future trials that include twins. Publication of additional ICCs is needed to further assist with sample size planning for future trials.

Correlation between neonatal outcomes of twins depends on the outcome: secondary analysis of twelve randomised controlled trials

OBJECTIVE

To estimate the magnitude of the correlation between neonatal outcomes of twins and demonstrate how this information can be used in the design of randomised controlled trials (RCTs) in women with twin pregnancies.

DESIGN

Secondary analysis of data from 12 RCTs.

SETTING

Obstetric care in multiple countries, 2004-2012.

POPULATION OR SAMPLE

4504 twin pairs born to women who participated in RCTs to assess treatments given during pregnancy.

METHODS

Intraclass correlation coefficients (ICCs) were estimated using log-binomial and linear models.

MAIN OUTCOME MEASURES

Perinatal death, respiratory distress syndrome, bronchopulmonary dysplasia, intraventricular haemorrhage, necrotising enterocolitis, sepsis, neonatal intensive care unit admission, birthweight, low birthweight and two composite measures of adverse neonatal outcome.

RESULTS

ICCs for the composite measures of adverse neonatal outcome were all above 0.5, indicating moderate to strong correlation between adverse outcomes of twins. For individual neonatal outcomes, median ICCs across trials ranged from 0.13 to 0.79 depending on the outcome. An example illustrates how ICCs can be used in sample size calculations for RCTs in women with twin pregnancies.

CONCLUSIONS

The correlation between neonatal outcomes of twins varies considerably between outcomes and may be lower than expected. Our ICC estimates can be used for designing and analysing RCTs that recruit women with twin pregnancies and for performing meta-analyses that include such RCTs. Researchers are encouraged to report ICCs for neonatal outcomes in twins in their own RCTs.

TWEETABLE ABSTRACT

Correlation between neonatal outcomes of twins depends on the outcome and may be lower than expected.

Antenatal Corticosteroid Prophylaxis in Singleton and Multiple Pregnancies

BACKGROUND

The effects of antenatal corticosteroids (ANS) in multiple pregnancies are disputed. In this article, we examined whether estimated effects differ in singletons and multiples and in small for gestational age (SGA) preterm infants.

METHODS

We studied 17 073 singletons (81% treated with ANS) and 8274 multiples (86% treated) born at 24-33 weeks from the Italian Neonatal Network (2005-2013). We used Poisson regression models with robust variance to estimate adjusted risk ratios (RR) of in-hospital death, severe intraventricular haemorrhage (IVH), periventricular leukomalacia (PVL), and the composite outcome of severe IVH and death.

RESULTS

Mortality was lower among ANS-treated vs. ANS-untreated infants, both in singletons (RR 0.63, 95% confidence interval (CI) 0.58, 0.68) and in multiples (RR 0.85, 95% CI 0.73, 0.98). IVH and the composite outcome of IVH and death, but not PVL, also occurred less frequently among ANS-treated infants. For these outcomes, the effect of ANS was stronger in singletons than in multiples (+35%, +32%, and +22% for death, IVH, and the composite outcome, respectively). Also among SGA infants, singletons, and multiples, ANS-treated infants had lower risk of death, IVH and of composite outcome than untreated ones.

CONCLUSIONS

In this large cohort of preterm infants, both multiples and singletons treated with ANS had a lower risk of mortality, of severe IVH, and of composite outcome of IVH and death, both in the overall sample and in SGA infants. Although ANS effect was weaker in multiples, our results support current recommendations to administer ANS prophylaxis in multiple pregnancies at risk of preterm delivery.

Policy of feeding very preterm infants with their mother's own fresh expressed milk was associated with a reduced risk of bronchopulmonary dysplasia

AIM

Since 2005, the French Food Safety Agency has recommended that very preterm or low-birthweight babies should be fed with pasteurised, expressed breastmilk, and feeding policies on this vary widely in French neonatal units. We investigated the differences between using a mother's expressed milk, in fresh or pasteurised forms, for very preterm infants.

METHODS

This observational multicentre study analysed data on 926 very preterm infants: 636 from neonatal units who used the mother's own fresh milk and 290 who used the mother's milk after pasteurisation. We analysed necrotising enterocolitis, bronchopulmonary dysplasia, in-hospital mortality, late-onset sepsis, weight gain, length of hospital stay, the duration of parenteral nutrition and the duration of enteral feeding with a nasogastric tube. Multivariate analyses were conducted to assess the impact of maternal milk policies.

RESULTS

After adjustment, there was a reduced risk of bronchopulmonary dysplasia in the fresh milk group with an odds ratio of 0.40 and 95% confidence interval of 0.27-0.67 (p < 0.001). No other statistically significant differences were observed.

CONCLUSION

Feeding very preterm infants with their mother's expressed fresh milk was associated with a reduced risk of bronchopulmonary dysplasia, and further investigations are needed to evaluate the clinical impact of this practice.

A Randomized Controlled Trial of End-Tidal Carbon Dioxide Detection of Preterm Infants in the Delivery Room

OBJECTIVE

To compare the ability of qualitative versus quantitative methods of end-tidal carbon dioxide (EtCO₂) detection to maintain normocarbia during face mask ventilation (FMV) of preterm infants (<32 weeks) in the delivery room.

STUDY DESIGN

Preterm infants <32 weeks were randomly assigned to the use of a disposable PediCap EtCO₂ detector (Covidien, Dublin, Ireland) (qualitative) or a Microstream side stream capnography device (Covidien) (quantitative) for FMV in the delivery room, via a NeoPuff T-piece resuscitator (Fisher and Paykel, Auckland, New Zealand). The primary outcome was the presence of normocarbia, based on partial pressure of CO₂ (PaCO₂) readings obtained in the neonatal intensive care unit within an hour of birth. Normocarbia was defined as a PaCO₂ measure between 37.5 and 60 mm Hg (5-8 kPa).

RESULTS

Of the 59 infants included, 59% (35/59) were within the PaCO₂ target range within an hour of birth. There was no difference in the primary outcome; 64% (21/33) of infants in the quantitative group were within the PaCO₂ range compared with 54% (14/26) in the qualitative group (P = .594); and 93% of participants <28 weeks' gestation were within the PaCO₂ normocarbic range (90% [9/10] in quantitative group and 100% [5/5] in the qualitative group [P = 1]). There was no difference in the intubation rate, days of ventilation, or bronchopulmonary dysplasia rates between the 2 groups.

CONCLUSIONS

Quantitative or qualitative EtCO₂ detection methods are both feasible for FMV in the delivery room. Although there was no difference in the incidence of normocarbia, the use of either form of EtCO₂ monitoring should be considered during newborn stabilization, especially in infants less than 28 weeks' gestation.

TRIAL REGISTRATION

ISRCTN: ISRCTN10934870.

Methodological issues in the design and analyses of neonatal research studies: Experience of the NICHD Neonatal Research Network

Impressive advances in neonatology have occurred over the 30 years of life of The Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network (NRN). However, substantial room for improvement remains in investigating and further developing the evidence base for improving outcomes among the extremely premature. We discuss some of the specific methodological challenges in the statistical design and analysis of randomized trials and observational studies in this population. Challenges faced by the NRN include designing trials for unusual or rare outcomes, accounting for and explaining center variations, identifying other subgroup differences, and balancing safety and efficacy concerns between short-term hospital outcomes and longer-term neurodevelopmental outcomes. In conclusion, the constellation of unique patient characteristics in neonates calls for broad understanding and careful consideration of the issues identified in this article for conducting rigorous studies in this population.

Randomized Trial of Late Surfactant Treatment in Ventilated Preterm Infants Receiving Inhaled Nitric Oxide

OBJECTIVE

To assess whether late surfactant treatment in extremely low gestational age (GA) newborn infants requiring ventilation at 7-14 days, who often have surfactant deficiency and dysfunction, safely improves survival without bronchopulmonary dysplasia (BPD).

STUDY DESIGN

Extremely low GA newborn infants (GA ≤28 0/7 weeks) who required mechanical ventilation at 7-14 days were enrolled in a randomized, masked controlled trial at 25 US centers. All infants received inhaled nitric oxide and either surfactant (calfactant/Infasurf) or sham instillation every 1-3 days to a maximum of 5 doses while intubated. The primary outcome was survival at 36 weeks postmenstrual age (PMA) without BPD, as evaluated by physiological oxygen/flow reduction.

RESULTS

A total of 511 infants were enrolled between January 2010 and September 2013. There were no differences between the treated and control groups in mean birth weight (701 ± 164 g), GA (25.2 ± 1.2 weeks), percentage born at GA <26 weeks (70.6%), race, sex, severity of lung disease at enrollment, or comorbidities of prematurity. Survival without BPD did not differ between the treated and control groups at 36 weeks PMA (31.3% vs 31.7%; relative benefit, 0.98; 95% CI, 0.75-1.28; P = .89) or 40 weeks PMA (58.7% vs 54.1%; relative benefit, 1.08; 95% CI, 0.92-1.27; P = .33). There were no between-group differences in serious adverse events, comorbidities of prematurity, or severity of lung disease to 36 weeks.

CONCLUSION

Late treatment with up to 5 doses of surfactant in ventilated premature infants receiving inhaled nitric oxide was well tolerated, but did not improve survival without BPD at 36 or 40 weeks. Pulmonary and neurodevelopmental assessments are ongoing.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01022580.

Very Low Birth Weight Monochorionic Diamniotic Twins as a Risk Factor for Symptomatic Patent Ductus Arteriosus

BACKGROUND

Some prior studies have shown that symptomatic patent ductus arteriosus (sPDA) is highly familial. Although it is estimated that both genetic and environmental factors may contribute to sPDA, evidence is still lacking.

OBJECTIVE

The aim of this study was to determine the risk factors for sPDA, focusing on the genetic and in utero environment by analyzing very low birth weight (VLBW) singletons and twins.

METHODS

This retrospective case-control study reviewed the medical records of 445 VLBW infants (25 weeks ≤ gestational age <32 weeks, 600 g ≤ birth weight <1,500 g) and compared the incidence of sPDA among monochorionic diamniotic (MD) twins (n = 65), dichorionic diamniotic (DD) twins (n = 66), and singletons (n = 314).

RESULTS

Stepwise multiple regression analysis showed that twin siblings (p = 0.001), gestational week (p < 0.001), antenatal steroid use (p = 0.021), and premature rupture of membranes (p = 0.002) were independent predictors of sPDA. Incidence of sPDA in MD twin siblings was significantly higher than that in singletons (p < 0.01), whereas no significant difference was found between singletons and DD twins or between MD and DD twins.

CONCLUSIONS

The current results show that being a VLBW MD twin is an independent risk factor for sPDA, and that both genetic and in utero environmental factors may contribute to its development.

Clinical trials of medicines in neonates: the influence of ethical and practical issues on design and conduct

In the past, there has been a perception that ethical and practical problems limit the opportunities for research in neonates. This perception is no longer appropriate. It is now clear that research about the medicines used in neonates is an ethical requirement. It is possible to conduct high quality research in neonates if the research team adapt to the characteristics of this population. Good practice involves respecting the specific needs of newborn babies and their families by adopting relevant approaches to study design, recruitment, pharmacokinetic studies and safety assessment. Neonatal units have a unique culture that requires careful development in a research setting. Clinical investigators need to recognize the clinical and ethical imperative to conduct rigorous research. Industry needs to engage with neonatal networks early in the process of drug development, preferably before contacting regulatory agencies. Follow-up over 3-5 years is essential for the evaluation of medicines in neonates and explicit funding for this is required for the assessment of the benefit and risk of treatments given to sick newborn babies. The views of parents must be central to the development of studies and the research agenda. Ethical and practical problems are no longer barriers to research in neonates. The current challenges are to disseminate good practice and maximize capacity in order to meet the need for research among newborn babies.

The ethics of neonatal research: An ethicist's and a parents' perspective

The ethics of neonatal research are complex because vulnerable new parents are asked to provide consent on behalf of their fragile baby. Whereas clinical neonatal care has evolved to value personalized and shared decision-making, the goal of research ethics is still to standardize the informed consent process and make it as complete and thorough as possible. Ethicists, lawyers and physicians have shaped the field of research ethics and consent for research. The goal of detailed informed consent is to protect participants from harm, but procedures were developed without input from the principal stakeholders: ex-neonatal intensive care unit parents/patients. Empirical investigations examining patient and parental perspectives on research and research ethics are lacking. Rigorous investigations are needed to determine how parents of sick neonates want their families to be protected, knowing that a lack of research is also harmful. Large randomized controlled multicenter trials will always be needed to improve neonatal outcomes. These trials are costly and time-consuming. Currently, the way in which research is funded and regulated and the way in which academic merit is recognized lead to inefficiency and a waste of precious resources. Following a review of the history of research ethics, this article examines and discusses the ethics of research in neonatology. In addition, challenges and opportunities are identified and ideas for future investigations are proposed.

Analysis of Randomised Trials Including Multiple Births When Birth Size Is Informative

BACKGROUND

Informative birth size occurs when the average outcome depends on the number of infants per birth. Although analysis methods have been proposed for handling informative birth size, their performance is not well understood. Our aim was to evaluate the performance of these methods and to provide recommendations for their application in randomised trials including infants from single and multiple births.

METHODS

Three generalised estimating equation (GEE) approaches were considered for estimating the effect of treatment on a continuous or binary outcome: cluster weighted GEEs, which produce treatment effects with a mother-level interpretation when birth size is informative; standard GEEs with an independence working correlation structure, which produce treatment effects with an infant-level interpretation when birth size is informative; and standard GEEs with an exchangeable working correlation structure, which do not account for informative birth size. The methods were compared through simulation and analysis of an example dataset.

RESULTS

Treatment effect estimates were affected by informative birth size in the simulation study when the effect of treatment in singletons differed from that in multiples (i.e. in the presence of a treatment group by multiple birth interaction). The strength of evidence supporting the effectiveness of treatment varied between methods in the example dataset.

CONCLUSIONS

Informative birth size is always a possibility in randomised trials including infants from both single and multiple births, and analysis methods should be pre-specified with this in mind. We recommend estimating treatment effects using standard GEEs with an independence working correlation structure to give an infant-level interpretation.

Sustained Aeration of Infant Lungs (SAIL) trial: study protocol for a randomized controlled trial

Background

Extremely preterm infants require assistance recruiting the lung to establish a functional residual capacity after birth. Sustained inflation (SI) combined with positive end expiratory pressure (PEEP) may be a superior method of aerating the lung compared with intermittent positive pressure ventilation (IPPV) with PEEP in extremely preterm infants. The Sustained Aeration of Infant Lungs (SAIL) trial was designed to study this question.

Methods/Design

This multisite prospective randomized controlled unblinded trial will recruit 600 infants of 23 to 26 weeks gestational age who require respiratory support at birth. Infants in both arms will be treated with PEEP 5 to 7 cm H₂O throughout the resuscitation. The study intervention consists of performing an initial SI (20 cm H₂0 for 15 seconds) followed by a second SI (25 cm H₂O for 15 seconds), and then PEEP with or without IPPV, as needed. The control group will be treated with initial IPPV with PEEP. The primary outcome is the combined endpoint of bronchopulmonary dysplasia or death at 36 weeks post-menstrual age.

Trial Registration

www.clinicaltrials.gov, Trial identifier NCT02139800, Registered 13 May 2014

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-0601-9) contains supplementary material, which is available to authorized users.

Multiples and parents of multiples prefer same arm randomization of siblings in neonatal trials

OBJECTIVE

Although common among Neonatal Intensive Care Units, multiples births are randomized inconsistently within trials, which can impact enrollment, analytical approach and trial outcomes. It is not known what randomization approach (same arm, different arm and independent randomization) is preferred by multiples and their families.

STUDY DESIGN

Surveys distributed to parents of multiples and adult multiples addressed the preferences on randomization by eliciting the most desired method and likelihood of enrolling twins for each randomization approach.

RESULT

Populations included 209 parents and 321 adult multiples. Seventy-eight percent of parents and 59% of multiples prefer same arm placement of multiples over other methods (both P<0.001), which also had highest likelihood of enrollment among both the groups.

CONCLUSION

Parents of multiples and adult multiples prefer placement of multiples into same treatment arm in randomized trials, making such methodology a potential way to optimize consent rates while ethically approaching human subject research.

Accounting for multiple births in randomised trials: a systematic review

OBJECTIVES

Multiple births are an important subgroup to consider in trials aimed at reducing preterm birth or its consequences. Including multiples results in a unique mixture of independent and clustered data, which has implications for the design, analysis and reporting of the trial. We aimed to determine how multiple births were taken into account in the design and analysis of recent trials involving preterm infants, and whether key information relevant to multiple births was reported.

DESIGN

We conducted a systematic review of multicentre randomised trials involving preterm infants published between 2008 and 2013. Information relevant to multiple births was extracted.

RESULTS

Of the 56 trials included in the review, 6 (11%) excluded multiples and 24 (43%) failed to indicate whether multiples were included. Among the 26 trials that reported multiples were included, only one (4%) accounted for clustering in the sample size calculations and eight (31%) took the clustering into account in the analysis of the primary outcome. Of the 20 trials that randomised infants, 12 (60%) failed to report how infants from the same birth were randomised.

CONCLUSIONS

Information on multiple births is often poorly reported in trials involving preterm infants, and clustering due to multiple births is rarely taken into account. Since ignoring clustering could result in inappropriate recommendations for clinical practice, clustering should be taken into account in the design and analysis of future neonatal and perinatal trials including infants from a multiple birth.

Association of assisted reproductive technology (ART) treatment and parental infertility diagnosis with autism in ART-conceived children

STUDY QUESTION

Are assisted reproductive technology (ART) treatment factors or infertility diagnoses associated with autism among ART-conceived children?

SUMMARY ANSWER

Our study suggests that the incidence of autism diagnosis in ART-conceived children during the first 5 years of life was higher when intracytoplasmic sperm injection (ICSI) was used compared with conventional IVF, and lower when parents had unexplained infertility (among singletons) or tubal factor infertility (among multiples) compared with other types of infertility.

WHAT IS KNOWN ALREADY

Some studies found an increased risk of autism among ART-conceived infants compared with spontaneously-conceived infants. However, few studies, and none in the USA, have examined the associations between types of ART procedures and parental infertility diagnoses with autism among ART-conceived children.

STUDY DESIGN, SIZE, DURATION

Population-based retrospective cohort study using linkages between National ART Surveillance System (NASS) data for 1996-2006, California Birth Certificate data for 1997-2006, and California Department of Developmental Services (DDS) Autism Caseload data for 1997-2011.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All live born ART-conceived infants born in California in 1997-2006 (n = 42 383) with 5-year observation period were included in the study. We assessed the annual incidence of autism diagnosis documented in DDS, which includes information on the vast majority of persons with autism in California, and the association of autism diagnosis with ART treatment factors and infertility diagnoses.

MAIN RESULTS AND THE ROLE OF CHANCE

Among ART-conceived singletons born in California between 1997 and 2006, the incidence of autism diagnosis remained at ∼0.8% (P for trend 0.19) and was lower with parental diagnosis of unexplained infertility (adjusted hazard risk ratio [aHRR]; 95% confidence interval: 0.38; 0.15-0.94) and higher when ICSI was used (aHRR 1.65; 1.08-2.52), when compared with cases without these patient and treatment characteristics. Among ART-conceived multiples, the incidence of autism diagnosis between 1997 and 2006 remained at ∼1.2% (P for trend 0.93) and was lower with parental diagnosis of tubal factor infertility (aHRR 0.56; 0.35-0.90) and higher when ICSI was used (aHRR 1.71; 1.10-2.66).

LIMITATIONS, REASONS FOR CAUTION

Study limitations include imperfect data linkages, lack of data on embryo quality and possible underestimation of autism diagnosis cases. Limitations of the observational study design could affect the analysis by the possibility of residual confounders. Since information about ICSI use was missing for most frozen/thawed embryo transfer cycles, our findings of association of ICSI use and autism diagnosis can only be generalizable to fresh embryo transfer cycles.

WIDER IMPLICATIONS OF THE FINDINGS

Our study provides additional evidence of the association between some types of ART procedures with autism diagnosis. Additional research is required to explain the increased risk of autism diagnosis with ICSI use, as well as studies on the effectiveness and safety of ICSI.

Clustering in Northern Territory Perinatal Data for 2003–2005: Implications for Analysis and Interpretation

Clustering in perinatal data can violate assumptions of independence, an important consideration for data analysis. Few published studies report on the extent of repeat births in routinely collected Australian perinatal data and the implications thereof for analysis and interpretation. This paper reports on a case study that examined the extent and implications of clustering in the Northern Territory Midwives Collection (NTMC) for the period 2003–2005. Data were obtained on 7,741 individual mothers giving birth to 8,707 babies in public hospitals during 2003–2005. Clusters of multiple pregnancies and repeat births were identified and the design effects for birth weight of Aboriginal and non-Aboriginal newborns were calculated. Of the mothers, 46.1% were Aboriginal. Of these, 13.2% had repeat singleton births; 0.4% had multiple pregnancies, and 0.3% had both. Of non-Aboriginal mothers, 8.7% had repeat singleton births; 1.2% had multiple pregnancies; and 0.3% had both. The design effect was 1.07 for Aboriginal newborns and 1.04 for non-Aboriginal newborns. The design effects indicate that the correct variance accounting for clustering is 4–7% larger than the incorrect variance ignoring clustering when three consecutive years of NT data are considered and an intracluster correlation coefficient of 0.48 is assumed for birth weight between twin and non-twin siblings. Depending on the outcome of interest, the impact of clustering should be considered in multivariate analysis of perinatal data, especially when such analyses involve more than one year's data, include large proportions of Aboriginal mothers and newborns, and groups with different rates of repeat births.

Morphologic abnormalities in 2-year-old children born after in vitro fertilization/intracytoplasmic sperm injection with preimplantation genetic screening: follow-up of a randomized controlled trial

OBJECTIVE

To evaluate the effect of preimplantation genetic screening (PGS) on morphologic outcome in children.

DESIGN

Follow-up of a randomized controlled trial (RCT).

SETTING

University hospital.

PATIENT(S)

Two-year-old children born to mothers who participated in an RCT on the efficacy of PGS: 50 children born after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) with PGS (intervention group; PGS+) and 72 children born after IVF/ICSI only (control group; PGS-). Sixty-six age-matched children conceived without any form of assisted reproduction were recruited separately in a local public health service center (reference group).

INTERVENTION(S)

PGS.

MAIN OUTCOME MEASURE(S)

Body surface examination and anthropometry. The evaluation of morphologic abnormalities allowed assessment of children's phenotype in detail. Morphologic abnormalities were classified as major abnormalities (abnormal development in organogenesis, deformations, disruptions, or dysplasia) and minor anomalies (deviations in phenogenesis).

RESULT(S)

The percentage of children with ≥ 1 major abnormality was 28% in the PGS+ and 35% in the PGS- group [difference -7%, 95% CI -23% to 10%]. The percentage of children with ≥ 1 minor anomaly was 64% in the PGS+ and 67% in the PGS- group [difference -3%, 95% CI -15% to 20%]. In the reference group 30% of the children had ≥ 1 major abnormality [95% CI 20% to 43%] and 74% had ≥ 1 minor anomaly [95% CI 62% to 84%].

CONCLUSION(S)

No statistically significant differences were found in minor anomalies between children conceived after IVF/ICSI with or without PGS. There is < 2.5% chance of ≥ 10% more major abnormalities in children born after PGS.

Perinatal outcomes of multiple births in southwest Nigeria

Compared to singletons, multiple births are associated with a substantially-higher risk of maternal and perinatal mortality worldwide. However, little evidence exists on the perinatal profile and risk of neurodevelopmental disabilities among the survivors, especially in developing countries. This cross-sectional study, therefore, set out to determine the adverse perinatal outcomes that are potential markers for neurodevelopmental disabilities in infants with multiple gestations in a developing country. In total, 4,573 mothers, and their 4,718 surviving offspring in an inner-city maternity hospital in Lagos, Nigeria, from May 2005 to December 2007, were recruited. Comparisons of maternal and infant outcomes between single and multiple births were performed using multivariable logistic regression and generalized estimation equation analyses. Odds ratio (OR) and the corresponding 95% confidence interval (CI) for each marker were estimated. Of the 4,573 deliveries, there were 4,416 (96.6%) singletons and 157 (3.4%) multiples, comprising 296 twins and six triplets together (6.4% of all live 4,718 infants). After adjusting for maternal age, ethnicity, occupation, parity, and antenatal care, multiple gestations were associated with increased risks of hypertensive disorders and caesarean delivery. Similarly, after adjusting for potential maternal confounders, multiple births were associated with low five-minute Apgar score (OR: 1.47, 95% CI 1.13-1.93), neonatal sepsis (OR: 2.16, 95% CI 1.28-3.65), severe hyperbilirubinaemia (OR: 1.60, 95% CI 1.00-2.56), and admission to a special-care baby unit (OR: 1.56, 95% CI 1.12-2.17) underpinned by preterm delivery before 34 weeks (OR: 1.91, 95% CI 1.14-3.19), birthweight of less than 2,500 g (OR: 6.45, 95% CI 4.80-8.66), and intrauterine growth restriction (OR: 9.04, 95% CI 6.62-12.34). Overall, the results suggest that, in resource-poor settings, infants of multiple gestations are associated with a significantly-elevated risk of adverse perinatal outcomes. Since these perinatal outcomes are related to the increased risk of later neurodevelopmental disabilities, multiple-birth infants merit close developmental surveillance for timely intervention.

Analysis of binary outcomes from randomised trials including multiple births: when should clustering be taken into account?

Randomised trials involving infants from both single and multiple births present unique statistical challenges. A range of methods have been used to analyse such data, including standard methods which treat all infants as independent, and more complex methods which account for the dependence between outcomes of infants from the same pregnancy. Conflicting recommendations have been made regarding if and when this dependence, or clustering, should be taken into account in the analysis. We studied the performance of ordinary logistic regression, which ignores the clustering, compared with logistic generalised estimating equations (GEEs) and mixed effects models (MEMs), which account for the clustering, using real and simulated datasets. Ordinary logistic regression produced appropriate type I error and coverage rates, provided the dependence between outcomes of infants from the same pregnancy was small and the multiple birth rate was low, but performed poorly otherwise. The type I error rate increased and the coverage rate decreased as either the strength of the dependence or the multiple birth rate increased. In contrast, logistic GEEs maintained appropriate type I error and coverage rates across a wide range of settings. The performance of logistic MEMs varied depending on the setting and the estimation procedure used but was often similar to or better than ordinary logistic regression. We recommend using a method which takes the clustering into account when analysing datasets including infants from multiple births.