Late preterm birth: a review of medical and neuropsychological childhood outcomes

Using an Optimality Index to Understand Perinatal Health Disparities: A Pilot Study With Latina Immigrants

PURPOSE

This study demonstrates preliminary evidence of the utility of an optimality index as a simple tool for monitoring complications across the perinatal period.

METHOD

The medical records of 147 Latina women participating in a preventive randomized controlled trial for perinatal depression were reviewed for outcomes across the perinatal period.

RESULTS

Application of the optimality index found optimality scores ranging from 77.3% to 97.7% in a Latina immigrant population known to have low rates of low-birthweight infants and preterm birth. Optimality scores were significantly lower among women who had a preterm birth or low-birthweight infant.

DISCUSSION

The ability of optimality indices to capture within-group variability will allow for a more nuanced understanding of the antecedents and sequelae of negative birth outcomes.

IMPLICATIONS FOR PRACTICE

Increasing reliance on electronic medical records will facilitate the calculation of optimality scores that can be used to track patterns of perinatal health disparities.

Pathways of neuronal and cognitive development in children born small-for-gestational age or late preterm

OBJECTIVE

To assess the effects of late small-for-gestational-age (SGA) birth and late prematurity on cognitive outcomes and structural changes in the central nervous system at primary school age, using a novel approach to examine changes in neuronal integrity of the retina.

METHODS

We conducted a cross-sectional study of 347 children aged 6-13 years, including in the analysis only infants born after 34 weeks' gestation. We recorded all perinatal outcomes through a survey of parents. Neuronal damage was evaluated using optical coherence tomography of the retina. In a subgroup of 112 children aged 6-8 years, visuospatial perception was evaluated with the Children's Bender Visual Motor Gestalt Test.

RESULTS

The proportions of SGA and late preterm children were 11.8 and 6.3%, respectively. Prematurity and SGA were simultaneously present in five children. When compared with controls, SGA children showed significantly lower than average retinal nerve fiber layer (RNFL) thickness (94.1 vs 98.8 μm; P = 0.007) and an increased percentage of abnormal Bender scores (27.3 vs 6.2%; P = 0.017) (odds ratio 5.6 (95% CI, 1.2-26.8)). These differences increased when late SGA infants with a birth weight below the 3(rd) percentile were compared with SGA infants with a birth weight between the 3(rd) and 10(th) percentiles and with controls, for RNFL thickness (92.5 vs 94.6 and 98.8 μm, respectively; P = 0.021) and abnormal Bender tests (33.3 vs 25.0 and 6.2%, respectively; P = 0.036). However, no differences were found in retinal structure and visuomotor performance between late preterm and term infants.

CONCLUSIONS

These data suggest that late SGA and late prematurity induce a distinct neuronal pattern of structural changes that persist at school age. Late-onset SGA infants are at increased risk for axonal loss in the retina and present specific visuomotor difficulties.

Polymorphisms of CYP51A1 from cholesterol synthesis: associations with birth weight and maternal lipid levels and impact on CYP51 protein structure

We investigated the housekeeping cytochrome P450 CYP51A1 encoding lanosterol 14α-demethylase from cholesterol synthesis that was so far not directly linked to human disorders. By direct sequencing of CYP51A1 in 188 women with spontaneous preterm delivery and 188 unrelated preterm infants (gestational age <37 weeks) we identified 22 variants where 10 are novel and rare. In infants there were two novel CYP51A1 variants where damaging effects of p.Tyr145Asp from the substrate recognition region, but not p.Asn193Asp, were predicted by PolyPhen2 and SIFT. This was confirmed by molecular modeling showing that Tyr145Asp substitution results in changed electrostatic potential of the CYP51 protein surface and lengthened distance to the heme which prevents hydrogen bonding. The CYP51 Tyr145Asp mutation is rare and thus very interesting for further structure/function relationship studies. From the 12 identified known variants rs6465348 was chosen for family based association studies due to its high minor allele frequency. Interestingly, this CYP51A1 common variant associates with small for gestational age weight in newborns (p = 0.028) and lower blood total cholesterol and low density lipoprotein cholesterol levels in mothers in 2nd trimester of pregnancy (p = 0.042 and p = 0.046 respectively). Our results indicate a new link between a cholesterol synthesis gene CYP51A1 and pregnancy pathologies.

Long-term outcomes of moderately preterm, late preterm, and early term infants

At present, moderate preterm (MPT) infants born at 32 to 33 weeks' gestation and late preterm (LPT) infants born at 34 to 36 weeks' gestation make up the largest subgroup of preterm infants and contribute to more than 80% of premature births in the United States. There is increasing evidence that both MPT and LPT infants are at increased risk of neurologic impairments, developmental disabilities, school failure, and behavior and psychiatric problems. Population studies suggest that for each 1 week decrease in gestational age below 39 weeks, there are stepwise increases in adverse outcomes after adjusting for confounders.

Associations of preterm births with child health and development: Japanese population-based study

OBJECTIVE

To examine associations between the duration of gestation and health and development outcomes at 2.5 years and 5.5 years using a Japanese population-based longitudinal survey (n = 47 015).

STUDY DESIGN

Hospitalization was used as an indicator of physical health, and responses to questions about age-appropriate behaviors were used as an indicator of behavioral development. We conducted logistic regression analyses controlling for a set of neonatal and family factors. We also estimated population-attributable fractions.

RESULTS

We observed a steady increase toward shorter duration of gestation in the risk of hospitalizations at age 2.5 years and 5.5 years and developmental delays at 2.5 years (Plinear trend < .001 for all outcomes). We found associations only between extremely preterm birth and delayed behavioral development at age 5.5 years.

CONCLUSION

There is a linear relationship between shorter duration of gestation and increased risk of later health and developmental problems. In line with Rose's "population paradox," the population-attributable risks for these problems are greater for moderately preterm infants compared with extremely preterm infants.

Both low birthweight and high birthweight are associated with cognitive impairment in persons with schizophrenia and their first-degree relatives

BACKGROUND

Both low birthweight and high birthweight have been associated with an increased risk for schizophrenia and cognitive impairments in the general population. We assessed the association between birthweight and cognitive performance in persons with schizophrenia and their unaffected first-degree relatives.

METHOD

We investigated a population-based family sample comprising persons with schizophrenia (n = 142) and their unaffected first-degree relatives (n = 277). Both patients and relatives were interviewed with the Structured Clinical Interview for DSM-IV Axis I Disorders, Clinician Version (SCID-CV) and a comprehensive neuropsychological test battery was administered. Information on birthweight was obtained from obstetric records. We used generalized estimating equation (GEE) models to investigate the effect of birthweight, as a continuous variable, on cognitive functioning, adjusting for within-family correlation and relevant covariates.

RESULTS

Both low birthweight and high birthweight were associated with lower performance in visuospatial reasoning, processing speed, set-shifting and verbal and visual working memory among persons with schizophrenia and their unaffected first-degree relatives compared to individuals with birthweight in the intermediate range. The group × birthweight interactions were non-significant.

CONCLUSIONS

Both low birthweight and high birthweight are associated with deficits in cognition later in life. Schizophrenia does not seem to modify the relationship between birthweight and cognition in families with schizophrenia.

Preterm prelabour rupture of membranes: effect of latency on neonatal and maternal outcomes

OBJECTIVES

To compare risks of infection and prematurity-related outcomes according to latency periods among women with preterm prelabour rupture of membranes (PPROM).

METHODS

Women with PPROM occurring between 24+0 and 36+6 weeks of gestation were identified from a provincial population-based perinatal database in Nova Scotia. The primary outcomes included composite variables for serious maternal and neonatal infectious morbidity and neonatal prematurity-related morbidity. Logistic regression was used to quantify the relationship between latency period (< 24 hours, 24 hours to < 48 hours, 48 hours to < 7 days, and ≥ 7 days) and maternal and neonatal outcomes. Separate analyses were conducted for gestational age groups 24+0 to 33+6 weeks and 34+0 to 36+6 weeks.

RESULTS

There were 4329 women included in the cohort. The composite variables representing serious maternal or neonatal infectious morbidity were not significantly associated with latency for either gestational age group. For PPROM occurring at gestational ages of 24+0 to 33+6 weeks, the odds of neonatal prematurity-related morbidity were significantly decreased at the latency periods of 48 hours or more compared with < 24 hours latency. For PPROM at 34+0 to 36+6 weeks of gestation, the odds of prematurity-related morbidity at 48 hours to < 7 days latency was decreased compared with latencies < 24 hours (OR 0.4; 95% CI 0.2 to 0.8).

CONCLUSION

Postponing delivery following PPROM may contribute to less prematurity-related morbidity, even close to term, without putting mother or neonate at substantial risk for serious infectious morbidity. Generalization of these findings to other obstetric populations should be informed by the underlying risk of infection.

In vitro fertilization and late preterm preschoolers' neuropsychological outcomes: the PETIT study

OBJECTIVE

In vitro fertilization (IVF) is considered a generally safe procedure, although associated with a higher incidence of preterm birth. The literature is inconsistent about the psychological impact of IVF, and we found no reports about outcome in late preterm (LPT) children. Our objective was to study neuropsychological and behavioral outcomes in a cohort of preschoolers born LPT between 2004 and 2007.

STUDY DESIGN

Participants were 397 LPT children (mean age, 3.8 years) conceived assisted by IVF (n = 105) or non-IVF (n = 292). Standardized performance-based tests of general conceptual ability (intelligence quotient), executive function, focused/selective attention, visual-spatial perception, visual-motor skill, manual dexterity, learning, and memory were administered. Parents completed behavioral and executive function questionnaires.

RESULTS

IVF group characteristics included older maternal age (P < .001), lower birthweight (P < .001), and higher maternal education (P < .001). No main-effect significant group differences were found for any variable after controlling for these variables. However, sex differences were demonstrated for the neuropsychological variables in copying (P > .001), nonverbal reasoning (P = .001), manual dexterity (P = .001), and inhibitory capacity (P = .006), all favoring girls.

CONCLUSION

Birth following IVF-assisted conception did not increase the risk of intellectual, neuropsychological, or behavioral deficit in LPT preschoolers. As shown in earlier gestational-age participants, girls have selective advantages. These findings should be reassuring for parents who conceive through IVF and deliver infants 1-3 weeks before term gestational age. Future study of these children at elementary school age may detect subtle impairments not yet apparent at age 3 years.

Late-preterm birth and lifetime socioeconomic attainments: the Helsinki birth cohort study

OBJECTIVE

We examined if those born late-preterm (at 34 to 36 weeks of gestation) differed from those born at term in their maximum attained lifetime socioeconomic position (SEP) across the adult years up to 56 to 66 years, and in intergenerational social mobility from childhood parental SEP to own attained SEP.

METHODS

Participants were 8993 Finnish men and women of the Helsinki Birth Cohort Study born between 1934 and 1944. Gestational age was extracted from hospital birth records and socioeconomic attainments from Finnish National Census.

RESULTS

Compared with those born at term, those born late-preterm were more likely to be manual workers, have a basic or upper secondary level of education, belong to the lowest third based on their incomes, and less likely to belong to the highest third based on their incomes. Late-preterm individuals were also less likely to be upwardly mobile and more likely to be downwardly mobile; they were less likely to have higher occupations and more likely to have lower occupations than their fathers. They were also less likely to be upwardly mobile if incomes were used as the outcome of own attained SEP, and men were more likely to be downwardly mobile if education was used as the outcome of own attained SEP.

CONCLUSIONS

This study demonstrates that there are considerable long-term socioeconomic disadvantages associated with late-preterm birth, which are not explained by the parent-of-origin SEP.

Ambulatory assessments of psychological and peripheral stress-markers predict birth outcomes in teen pregnancy

OBJECTIVE

Pregnant adolescents have high rates of poor birth outcomes, but the causes are unclear. We present a prospective, longitudinal study of pregnant adolescents assessing associations between maternal psychobiological stress indices and offspring gestational age at birth and birthweight.

METHOD

Healthy nulliparous pregnant adolescents were recruited (n=205) and followed during pregnancy. Ambulatory assessments over 24h of perceived psychological stress (collected every 30 min) and salivary cortisol (6 samples) and a summary questionnaire, the Perceived Stress Scale, were collected at three time points (13-16, 24-27, and 34-37 gestational weeks). Corticotropin-releasing hormone, C-reactive protein, and interleukin 6 were assayed from blood taken at the latter 2 sessions. A final sample of 119 participants was selected for analyses.

RESULTS

The ambulatory assessment of perceived psychological stress was positively correlated with the Perceived Stress Scale (r=.20, p=.03) but neither was associated with any of the biological assays (all ps>.20). Based on backward selection regression models that included all stress variables and relevant covariates, the ambulatory assessments of perceived psychological stress and cortisol - though not the Perceived Stress Scale - were negatively associated with gestational age at birth (F(4, 107)=3.38, p=.01) while cortisol was negatively related to birthweight (F(5, 107)=14.83, p<.0001).

CONCLUSIONS

Targeted interventions to reduce psychological and biological indicators of heightened stress during pregnancy may have positive public health benefits for the offspring given the associations of shortened gestation and lower birthweight with risk for poor mental and physical health outcomes.

Single-nucleotide polymorphism associations with preterm delivery: a case-control replication study and meta-analysis

BACKGROUND

The aim of this study was to replicate single-nucleotide polymorphism (SNP) associations with preterm birth (PTB; birth at <37 completed weeks of gestation) and synthesize currently available evidence using meta-analysis.

METHODS

Spontaneous PTB cases and controls were selected from an existing cohort. Candidate SNPs were taken from an existing genotype panel. A systematic review was conducted for each SNP in the panel to determine suitability as a PTB candidate. Those with significant associations previously reported in Caucasians were selected for replication. Candidate SNPs were already genotyped in cases and controls and clinical data were accessed from state perinatal and cerebral palsy databases. Association analysis was conducted between each SNP and PTB, and meta-analysis was conducted if there were ≥ 3 studies in the literature. Maternal and fetal SNPs were considered as separate candidates.

RESULTS

A cohort of 170 cases and 583 controls was formed. Eight SNPs from the original panel of genotyped SNPs were selected as PTB candidates and for replication on the basis of systematic literature review results. In our cohort, fetal factor V Leiden (FVL) was significantly associated with PTB (odds ratio (OR): 2.6, 95% confidence interval (CI): 1.31-5.17), and meta-analysis confirmed this association (OR: 2.71, 95% CI: 1.15-6.4).

CONCLUSION

Replication and meta-analysis support an increased risk of PTB in Caucasians with the fetal FVL mutation.