The pathophysiology of neonatal meconium aspiration syndrome (MAS) is related to mechanical obstruction of the airways and to chemical pneumonitis. It has also been suggested that meconium causes inhibition of surfactant function. To assess its in vitro effect on surfactant function and morphology, we used a pulsating bubble surfactometer to measure the dynamic surface tension of meconium-surfactant mixtures and observed their electron microscopic structures. The mixtures were prepared by adding serial dilutions of human meconium to various concentrations of Surfactant-TA (Surfacten) that had been used for the prevention and treatment of neonatal respiratory distress syndrome. Inhibition of the surface tension-lowering properties of Surfactant-TA was caused by the addition of meconium and depended on the concentration of the surfactant; the inhibition could be overcome by increasing the surfactant concentration. When meconium was added to Surfactant-TA, the characteristic ultrastructural features of the latter, the loosely stacked layers, changed to a spherical lamellar structure and folded linear structures. These results suggest that meconium inhibits surfactant function by altering surfactant morphology. Our morphologic and functional findings support the new concept that surfactant inhibition may play a role in the pathophysiology of MAS.

Although Cesarean section (CS) itself has contributed to the reduction in maternal and perinatal mortality, an undue rise in the CS rate (CSR) has been issued in Korea as well as globally. The CSR in Korea increased over the past two decades, but has remained at approximately 36% since 2006. Contributing factors associated with the CSR in Korea were an improvement in socio-economic status, a higher maternal age, a rise in multiple pregnancies, and maternal obesity. We found that countries with a no-fault compensation system maintained a lower CSR compared to that in countries with civil action, indicating the close relationship between the CSR and the medico-legal system within a country. The Korean government has implemented strategies including an incentive system relating to the CSR or encouraging vaginal birth after Cesarean to decrease CSR, but such strategies have proved ineffective. To optimize the CSR in Korea, efforts on lowering the maternal childbearing age or reducing maternal obesity are needed at individual level. And from a national view point, reforming health care system, which could encourage the experienced obstetricians to be trained properly and be relieved from legal pressure with deliveries is necessary.Graphical Abstract

The reference level of serum CysC was determined according to postnatal age and PCA. As the reference CysC level was dependent on gestational age and PCA, consideration of these parameters is warranted when assessing CysC levels in neonates.

BackgroundAs the aging society progresses, the average age of mothers is also increasing. Advanced maternal age has been known to be associated with perinatal outcomes, as well as birth weight (BW). In this study, we aimed to investigate the perinatal factors associated with low birth weight infants (LBWIs) using birth statistics of the Korean population.MethodsBirth statistics between 1993 and 2016 from the Korean Statistical Information Service were reviewed. We investigated 12,856,614 data points, which included the number of births, BWs, percentage of preterm births and LBWIs, multiple pregnancies, and maternal age.ResultsThe proportion of LBWIs delivered by mothers of advanced maternal age has gradually increased since 1993. In addition, the proportion of older mothers (≥ 35 years old) giving birth to LBWIs has increased over the years. Average BW has a negative correlation with the ratio of preterm births, LBW, multiple births, and advanced maternal age. The mean BW also has a negative correlation with maternal age.ConclusionThis study shows that the average BW continues to decline, and the incidence of LBWIs is increasing in Korea since 1993. This study also revealed that several perinatal factors, including percentage of preterm births, LBWIs, multiple births, and maternal age influence the mean BW. Although this study did not investigate the effects of decreasing mean BW on perinatal health, future research is worth discussing.

Immunogenicity and safety of a quadrivalent meningococcal tetanus toxoid-conjugate vaccine administered concomitantly with other paediatric vaccines in toddlers: a phase III randomised study. Epidemiology and Infection 149, e90, 1-10.