Presenting Twins Are Exposed to Higher Levels of Inflammatory Mediators than Nonpresenting Twins as Early as the Midtrimester of Pregnancy

Funisitis as a Risk Factor for Adverse Neonatal Outcomes in Twin Neonates with Spontaneous Preterm Birth: A Retrospective Cohort Study

PURPOSE

Funisitis, inflammation of the umbilical cord, is considered a strong risk factor for adverse neonatal outcomes; however, a clinical definition of funisitis has not been established. In this study, we aimed to determine the clinical significance of funisitis in twin neonates with spontaneous preterm birth.

MATERIALS AND METHODS

The study included preterm twin neonates (<35 weeks) delivered after spontaneous preterm labor and/or preterm premature rupture of amniotic membranes. The presence of funisitis was examined in the umbilical cord of each twin. We analyzed the risk of adverse neonatal outcomes according to the presence and absence of funisitis. Adverse neonatal outcomes were defined as the occurrence of neonatal mortality, significant morbidity, or both.

RESULTS

Among 474 preterm neonates (237 twin pairs) included in this study, the frequency of funisitis was 6.5% (31 cases). Funisitis was significantly associated with neonatal mortality and adverse neonatal outcomes after adjustment for confounding variables [neonatal mortality, odds ratio (OR) 9.043, 95% confidence interval (CI) 2.620-31.204; adverse neonatal outcome, OR 2.445, 95% CI 1.017-5.875]. The concordance rate of funisitis between the twins was 10.7%, and in the absence of funisitis in one twin, the risk of neonatal mortality or adverse neonatal outcome was not influenced by the presence of funisitis in the other twin.

CONCLUSION

The presence of funisitis appears to be associated with an increased risk for adverse neonatal outcomes in twin neonates with spontaneous preterm birth.

The effects of birth order on neonatal outcomes in early-preterm, late-preterm and term twin infants

Objectives: Birth order is one of the main factors that influences the neonatal outcome of twins. However, there is little prior data regarding the effect of birth order under different clinical circumstances. This study investigates the effect of birth order on the neonatal outcomes of twins delivered during early-preterm, late-preterm and term gestations according to chorionicity, delivery mode and indication for delivery.Methods: This is a retrospective cohort study of women with twin pregnancies delivered at 24-40 weeks of gestation between 1995 and 2014. We excluded twin pregnancies with the following complications: twin-to-twin transfusion syndrome, monoamnionic twins, delayed interval delivery and fetal death, chromosomal anomalies or major congenital malformation in one or more of the twins. The neonatal outcomes, including death, admission to neonatal intensive care unit (NICU), mechanical ventilator support, and respiratory distress syndrome (RDS) was compared between the first and second twin born at early-preterm (24-33 weeks of gestation), late-preterm (34-36 weeks of gestation) and term (≥37 weeks of gestation) gestations. These outcomes were further analyzed according to chorionicity, mode of delivery and indication for delivery by multivariable analysis (after adjusting for sex, presentation, and birth weight).Results: Among a total of 1,614 women with twin pregnancies who met the selection criteria, 423, 674 and 517 women delivered at early-preterm, late-preterm and term gestation, respectively. Overall, the second-born twins were lighter and had higher rates of NICU admission, mechanical ventilator support, and RDS than did first-born twins. Second twins born at early-preterm gestation had higher rates of RDS and mechanical ventilator support than did first twins. Second twins born at late-preterm gestation had higher rates of NICU admission and mechanical ventilator support than did first twins. Second twins born at term gestation also had a higher NICU admission rate than did first twins. However, in the multivariable analysis of the subgroups, the rates of NICU admission, mechanical ventilator support and RDS were not significantly different between most twin pairs. However, there were several significant differences. There was a higher risk of RDS in the second twins in the early-preterm premature rupture of membranes (PROM) subgroup, and a higher risk of mechanical ventilator support in the late-preterm PROM subgroup. Low birth weight was the only significant factor independently associated with a higher risk of adverse neonatal outcome in the second twins compared with the first twins in all subgroups.Conclusions: Second twins born at early-preterm, late-preterm and term were at higher risk of adverse neonatal outcome than were their respective first twins. However, this finding was mainly represented lower birth weight of the second twin. Still, second twins delivered due to early-preterm and late-preterm PROM had a higher risk of RDS and mechanical ventilator support, respectively, than did the first twin after adjusting for birth weight.

Risk of intra-amniotic infection/inflammation and respiratory distress syndrome according to the birth order in twin preterm neonates

Objective: Prior studies have suggested that nonpresenting twins are more likely to develop respiratory distress syndrome (RDS) than presenting twins. While the underlying mechanism is not known, exposure to intra-amniotic infection/inflammation (IAI) has been associated with a reduced risk of RDS in singleton gestations. In the current study, we compared the risk of RDS in preterm twin neonates according to birth order with adjustment for the presence or absence of IAI.Methods: The study population consisted of consecutive twin neonates who delivered ≤35 weeks and underwent amniocentesis within 7 days of delivery. The frequency of RDS and IAI was compared between presenting and nonpresenting twin pairs. Amniotic fluid (AF) was cultured for aerobic/anaerobic bacteria and genital mycoplasma. IAI was defined as a positive AF culture or an AF white cell count ≥19/mm³.Results: A total of 120 twin pairs were enrolled. Compared with presenting twins, nonpresenting twins had a lower risk of IAI (36 vs. 26%, respectively, p < .05), but a higher risk of RDS (18 vs. 25%, respectively, p < .05). In multivariate analysis, only IAI remained significantly associated with RDS (OR 0.18, 95% CI 0.05-0.65), whereas birth order was not.Conclusions: In preterm twin neonates, the increased risk of RDS in nonpresenting twins is likely due to lower exposure to IAI and not birth order.

Neuropsychological Functioning in Preterm-Born Twins and Singletons at Preschool Age

OBJECTIVES

A limited body of research is available on the relationships between multiplicity of birth and neuropsychological functioning in preterm children who were conceived in the age of assisted reproductive technology and served by the modern neonatal intensive care unit. Our chief objective was to evaluate whether, after adjustment for sociodemographic factors and perinatal complications, twin birth accounted for a unique portion of developmental outcome variance in children born at-risk in the surfactant era.

METHODS

We compared the neuropsychological functioning of 77 twins and 144 singletons born preterm (<34 gestational weeks) and served by William Beaumont Hospital, Royal Oak, MI. Children were evaluated at preschool age, using standardized tests of memory, language, perceptual, and motor abilities.

RESULTS

Multiple regression analyses, adjusting for sociodemographic and perinatal variables, revealed no differences on memory or motor indices between preterm twins and their singleton counterparts. In contrast, performance of language and visual processing tasks was significantly lower in twins despite reduced perinatal risk in comparison to singletons. Effect sizes ranged from .33 to .38 standard deviations for global language and visual processing ability indices, respectively. No significant group by sex interactions were observed, and comparison of first-, or second-born twins with singletons yielded medium effect sizes (Cohen's d=.56 and .40, respectively).

CONCLUSIONS

The modest twin disadvantage on language and visual processing tasks at preschool-age could not be readily attributable to socioeconomic or perinatal variables. The possibility of biological or social twinning-related phenomena as mechanisms underlying the observed performance gaps are discussed. (JINS, 2016, 22, 865-877).

Keratin 12 missense mutation induces the unfolded protein response and apoptosis in Meesmann epithelial corneal dystrophy

Meesmann epithelial corneal dystrophy (MECD) is a rare autosomal dominant disorder caused by dominant-negative mutations within the KRT3 or KRT12 genes, which encode the cytoskeletal protein keratins K3 and K12, respectively. To investigate the pathomechanism of this disease, we generated and phenotypically characterized a novel knock-in humanized mouse model carrying the severe, MECD-associated, K12-Leu132Pro mutation. Although no overt changes in corneal opacity were detected by slit-lamp examination, the corneas of homozygous mutant mice exhibited histological and ultrastructural epithelial cell fragility phenotypes. An altered keratin expression profile was observed in the cornea of mutant mice, confirmed by western blot, RNA-seq and quantitative real-time polymerase chain reaction. Mass spectrometry (MS) and immunohistochemistry demonstrated a similarly altered keratin profile in corneal tissue from a K12-Leu132Pro MECD patient. The K12-Leu132Pro mutation results in cytoplasmic keratin aggregates. RNA-seq analysis revealed increased chaperone gene expression, and apoptotic unfolded protein response (UPR) markers, CHOP and Caspase 12, were also increased in the MECD mice. Corneal epithelial cell apoptosis was increased 17-fold in the mutant cornea, compared with the wild-type (P < 0.001). This elevation of UPR marker expression was also observed in the human MECD cornea. This is the first reporting of a mouse model for MECD that recapitulates the human disease and is a valuable resource in understanding the pathomechanism of the disease. Although the most severe phenotype is observed in the homozygous mice, this model will still provide a test-bed for therapies not only for corneal dystrophies but also for other keratinopathies caused by similar mutations.