Incidence and trend of preterm birth in China, 1990-2016: a systematic review and meta-analysis

Trends in the Incidence of High-Risk Newborns Based on a New Conceptual Framework - Beijing Municipality, China, 2013-2022

What is already known on this topic?

A new conceptual term, small and vulnerable newborns (SVN), bringing preterm birth, small for gestational age (SGA), or low birth weight (LBW) together is being advocated for assessing whether a child is at high risk.

What is added by this report?

According to the new conceptual term, the increasing incidence of high-risk newborns (from 9.82% to 10.96%) has been observed among 2,005,408 newborns over the period from 2013 to 2022, which is higher than using any of the three definitions of SVN. Maternal age ≥35, primiparity, and multiple births are high risks for SVN.

What are the implications for public health practice?

The new conceptual framework should be used to better assess the number of high-risk newborns. Attention should be paid to multiple births to prevent preterm-related SVN. To reduce term newborns who are SGA, we need to be concerned not only with multiple pregnancies but also with first-time mothers.

The effect of vitamin D deficiency during pregnancy on adverse birth outcomes in neonates: a systematic review and meta-analysis

Objective

To systematically evaluate the effect of vitamin D deficiency during pregnancy on neonatal adverse outcomes, such as preterm infants, low birth weight infants (LBWI), and small for gestational age (SGA) infants.

Methods

A comprehensive literature search was conducted across multiple databases including PubMed, Embase, Cochrane Library, SinoMed, Wanfang Data Knowledge Service Platform, China National Knowledge Internet (CNKI), and VIP Chinese Science and Technology Journal Database (VIP). Following predefined inclusion and exclusion criteria, two researchers independently screened, extracted data, and assessed the quality of the included studies. Meta-analysis was performed using RevMan 5.4 and Stata 14 software to synthesize the findings.

Results

This study incorporated 13 cohort studies from 8 different countries and regions, encompassing a total of 55,162 pregnant women, among whom 28,155 were identified as having vitamin D deficiency. The Newcastle-Ottawa Scale (NOS) score ranged from 7-9 points. Meta-analysis results indicated a higher incidence of LBWI (OR = 5.52, 95% CI = 1.31-23.22. P = 0.02) in the group of pregnant women with vitamin D deficiency compared to those with adequate levels. However, there was no statistically significant difference in the likelihood of premature birth (OR = 1.25, 95% CI = 0.78-1.99. P = 0.36) or SGA (OR = 1.47, 95% CI = 0.81-2.68. P = 0.21) among newborns born to mothers with vitamin D deficiency vs. those with sufficient levels of vitamin D. Subgroup analysis based on the timing of maternal blood collection revealed that there was no statistically significant association between vitamin D levels during pregnancy and the incidence of preterm birth across all stages of pregnancy. Furthermore, vitamin D deficiency throughout the entire pregnancy was associated with an increased incidence of neonatal LBWI, whereas vitamin D levels during the first, second, and third trimesters did not demonstrate statistically differences on LBWI. Neonates born to mothers with vitamin D deficiency throughout pregnancy were found to have a higher likelihood of developing SGA. However, there was no statistically significant association between vitamin D levels and the development of SGA during the first and second trimesters.

Conclusions

Adequate levels of vitamin D during pregnancy may decrease the incidence of LBWI, although further research is needed to determine its impact on the occurrence of preterm birth and SGA.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024535950, Identifier: (CRD42024535950).

Association of maternal mineral status with the risk of preterm birth: a retrospective cohort study

Background

There has been a gradual increase in the proportion of preterm birth in China during the past several decades. Maternal malnutrition is a significant determinant for preterm birth. Nevertheless, comprehensive studies investigating serum mineral levels during pregnancy associated with preterm birth remain scarce. This study aims to assess the associations between maternal serum mineral levels and the risk of preterm birth.

Methods

This retrospective cohort study of 18,048 pregnant women used data from a tertiary hospital in China from January 2016 to December 2022. Demographic data and serum mineral concentrations in the second and third trimesters of mothers were collected from the hospital information system. Analysis was performed using restricted cubic splines and logistic regression models.

Results

The proportion of preterm birth in this study was 6.01%. Phosphorus [P for overall = 0.005; P for nonlinear = 0.490; OR (95%CI) = 1.11 (1.04, 1.18)] and chlorine [P for overall = 0.002; P for nonlinear = 0.058; OR (95%CI) = 1.11 (1.03, 1.19)] showed a significant positive correlation with preterm birth in a linear fashion. Furthermore, serum levels of potassium (P for nonlinear <0.001), sodium (P for nonlinear = 0.004), and magnesium (P for nonlinear <0.001) exhibited non-linear relationships with the risk of preterm birth.

Conclusion

Serum levels of some minerals during pregnancy were associated with the risk of preterm birth among pregnant women. In addition to commonly recognized micronutrients such as folic acid, iron, and vitamin D, healthcare providers should also pay attention to the levels of these minerals during pregnancy.

[Repair effect of different doses of human umbilical cord mesenchymal stem cells on white matter injury in neonatal rats]

OBJECTIVES

To compare the repair effects of different doses of human umbilical cord mesenchymal stem cells (hUC-MSCs) on white matter injury (WMI) in neonatal rats.

METHODS

Two-day-old Sprague-Dawley neonatal rats were randomly divided into five groups: sham operation group, WMI group, and hUC-MSCs groups (low dose, medium dose, and high dose), with 24 rats in each group. Twenty-four hours after successful establishment of the neonatal rat white matter injury model, the WMI group was injected with sterile PBS via the lateral ventricle, while the hUC-MSCs groups received injections of hUC-MSCs at different doses. At 14 and 21 days post-modeling, hematoxylin and eosin staining was used to observe pathological changes in the tissues around the lateral ventricles. Real-time quantitative polymerase chain reaction was used to detect the quantitative expression of myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) mRNA in the brain tissue. Immunohistochemistry was employed to observe the expression levels of GFAP and neuron-specific nuclear protein (NeuN) in the tissues around the lateral ventricles. TUNEL staining was used to observe cell apoptosis in the tissues around the lateral ventricles. At 21 days post-modeling, the Morris water maze test was used to observe the spatial learning and memory capabilities of the neonatal rats.

RESULTS

At 14 and 21 days post-modeling, numerous cells with nuclear shrinkage and rupture, as well as disordered arrangement of nerve fibers, were observed in the tissues around the lateral ventricles of the WMI group and the low dose group. Compared with the WMI group, the medium and high dose groups showed alleviated pathological changes; the arrangement of nerve fibers in the medium dose group was relatively more orderly compared with the high dose group. Compared with the WMI group, there was no significant difference in the expression levels of MBP and GFAP mRNA in the low dose group (P>0.05), while the expression levels of MBP mRNA increased and GFAP mRNA decreased in the medium and high dose groups. The expression level of MBP mRNA in the medium dose group was higher than that in the high dose group, and the expression level of GFAP mRNA in the medium dose group was lower than that in the high dose group (P<0.05). Compared with the WMI group, there was no significant difference in the protein expression of GFAP and NeuN in the low dose group (P>0.05), while the expression of NeuN protein increased and GFAP protein decreased in the medium and high dose groups. The expression of NeuN protein in the medium dose group was higher than that in the high dose group, and the expression of GFAP protein in the medium dose group was lower than that in the high dose group (P<0.05). Compared with the WMI group, there was no significant difference in the number of apoptotic cells in the low dose group (P>0.05), while the number of apoptotic cells in the medium and high dose groups was less than that in the WMI group, and the number of apoptotic cells in the medium dose group was less than that in the high dose group (P<0.05). Compared with the WMI group, there was no significant difference in the escape latency time in the low dose group (P>0.05); starting from the third day of the latency period, the escape latency time in the medium dose group was less than that in the WMI group (P<0.05). The medium and high dose groups crossed the platform more times than the WMI group (P<0.05).

CONCLUSIONS

Low dose hUC-MSCs may yield unsatisfactory repair effects on WMI in neonatal rats, while medium and high doses of hUC-MSCs have significant repair effects, with the medium dose demonstrating superior efficacy.

Spatial-temporal distribution of preterm birth in China, 1990-2020: A systematic review and modelling analysis

BACKGROUND

Little is known about the long-term trends of preterm birth rates in China and their geographic variation by province.

OBJECTIVES

To estimate the annual spatial-temporal distribution of preterm birth rates in China by province from 1990 to 2020.

DATA SOURCES

We searched PubMed, EMBASE, Web of Science, CNKI, WANFANG and VIP from January 1990 to September 2023.

STUDY SELECTION AND DATA EXTRACTION

Studies that provided data on preterm births in China after 1990 were included. Data were extracted following the Guidelines for Accurate and Transparent Health Estimates Reporting.

SYNTHESIS

We assessed the quality of each survey using a 9-point checklist. We estimated the annual preterm birth risk by province using Bayesian multilevel logistic regression models considering potential socioeconomic, environmental, and sanitary predictors.

RESULTS

Based on 634 survey data from 343 included studies, we found a gradual increase in the preterm birth risk in most provinces in China since 1990, with an average annual increase of 0.7% nationally. However, the preterm birth rates in Inner Mongolia, Hubei, and Fujian Province showed a decline, while those in Sichuan were quite stable since 1990. In 2020, the estimates of preterm birth rates ranged from 2.9% (95% Bayesian credible interval [BCI] 2.1, 3.8) in Inner Mongolia to 8.5% (95% BCI 6.6, 10.9) in Jiangxi, with the national estimate of 5.9% (95% BCI 4.3, 8.1). Specifically, some provinces were identified as high-risk provinces for either consistently high preterm birth rates (e.g. Jiangxi) or relatively large increases (e.g. Shanxi) since 1990.

CONCLUSIONS

This study provides annual information on the preterm birth risk in China since 1990 and identifies high-risk provinces to assist in targeted control and intervention for this health issue.

Preterm Birth and Infantile Appendicitis

OBJECTIVE

To investigate the potential association between preterm birth and infantile appendicitis.

METHODS

We conducted a retrospective, multicenter, matched case-control study. This study included consecutive patients <1 year of age with surgery- or autopsy-confirmed appendicitis, admitted between December 2007 and May 2023. For each case, 10 healthy infants were randomly selected and matched by age. Infants were categorized as neonates (0 to 28 days) or older infants (>28 days and <1 year).

RESULTS

The study included 106 infants diagnosed with appendicitis (median age 2.4 months) and 1060 age-matched healthy controls. In the univariate analysis, preterm birth was significantly associated with the development of appendicitis within the first year of life (odds ratio [OR], 4.23; 95% confidence interval [CI], 2.67-6.70). Other factors associated with a higher risk of infantile appendicitis included being male (OR, 1.91; 95%CI, 1.25-2.94), weight-for-age z-score (OR, 0.72; 95%CI, 0.64-0.81), and exclusively fed on formula (OR, 2.95; 95%CI, 1.77-4.91). In multivariable analyses, preterm remained significantly associated with appendicitis (adjusted OR, 3.32; 95%CI, 1.76-6.24). Subgroup analysis revealed that a preterm birth history increased the risk of appendicitis in both neonates (adjusted OR, 4.56; 95%CI, 2.14-9.71) and older infants (adjusted OR, 3.63; 95%CI, 1.72-7.65). However, preterm did not significantly influence the incidence of appendiceal perforation.

CONCLUSIONS

Preterm infants have an increased risk of appendicitis during the first year of life. A preterm birth history may help improve the timely diagnosis of infantile appendicitis.

Combined exposure to PM2.5 and PM10 in reductions of physiological development among preterm birth: a retrospective study from 2014 to 2017 in China

Background

Preterm birth (PTB) has been linked with ambient particulate matter (PM) exposure. However, data are limited between physiological development of PTB and PM exposure.

Methods

Trimester and season-specific PM exposure including PM2.5 and PM10 was collected from Jiaxing between January 2014 and December 2017. Information about parents and 3,054 PTB (gestational age < 37 weeks) outcomes such as weight (g), head circumference (cm), chest circumference (cm), height (cm) and Apgar 5 score were obtained from birth records. We used generalized linear models to assess the relationship between PTB physiological developmental indices and PM2.5, PM10 and their combined exposures. A binary logistic regression model was performed to assess the association between exposures and low birth weight (LBW, < 2,500 g).

Results

Results showed that there were 75.5% of low birth weight (LBW) infants in PTB. Decreased PM2.5 and PM10 levels were found in Jiaxing from 2014 to 2017, with a higher PM10 level than PM2.5 each year. During the entire pregnancy, the highest median concentration of PM2.5 and PM10 was in winter (61.65 ± 0.24 vs. 91.65 ± 0.29 μg/m3) followed by autumn, spring and summer, with statistical differences in trimester-specific stages. After adjusting for several potential factors, we found a 10 μg/m3 increase in joint exposure of PM2.5 and PM10 during the entire pregnancy associated with reduced 0.02 week (95%CI: -0.05, -0.01) in gestational age, 7.9 g (95%CI: -13.71, -2.28) in birth weight, 0.8 cm in height (95%CI: -0.16, -0.02), 0.05 cm (95%CI: -0.08, - 0.01) in head circumference, and 0.3 (95%CI: -0.04, -0.02) in Apgar 5 score, except for the chest circumference. Trimester-specific exposure of PM2.5 and PM10 sometimes showed an opposite effect on Additionally, PM2.5 (OR = 1.37, 95%CI: 1.11, 1.68) was correlated with LBW.

Conclusion

Findings in this study suggest a combined impact of fine particulate matter exposure on neonatal development, which adds to the current understanding of PTB risk and health.

Time-varying effects are common in genetic control of gestational duration

Preterm birth is a major burden to neonatal health worldwide, determined in part by genetics. Recently, studies discovered several genes associated with this trait or its continuous equivalent-gestational duration. However, their effect timing, and thus clinical importance, is still unclear. Here, we use genotyping data of 31 000 births from the Norwegian Mother, Father and Child cohort (MoBa) to investigate different models of the genetic pregnancy 'clock'. We conduct genome-wide association studies using gestational duration or preterm birth, replicating known maternal associations and finding one new fetal variant. We illustrate how the interpretation of these results is complicated by the loss of power when dichotomizing. Using flexible survival models, we resolve this complexity and find that many of the known loci have time-varying effects, often stronger early in pregnancy. The overall polygenic control of birth timing appears to be shared in the term and preterm, but not very preterm, periods and exploratory results suggest involvement of the major histocompatibility complex genes in the latter. These findings show that the known gestational duration loci are clinically relevant and should help design further experimental studies.

A pilot study of Kangaroo mother care in early essential newborn care in resource-limited areas of China: the facilitators and barriers to implementation

BACKGROUND

Implementation of Kangaroo Mother Care (KMC) in resource-limited areas of China may face unique barriers, such as a lack of resources, geographic location and more traditional culture among others. This qualitative study analyses the facilitators and barriers to implementing KMC in county-level health facilities in resource-limited areas of China for the promotion of KMC on a larger scale.

METHODS

Participants from 4 of the 18 pilot counties where early essential newborn care was implemented through the Safe Neonatal Project and 4 control counties not enrolled in Safe Neonatal Project were selected using purposive sampling. A total of 155 participants were interviewed, including stakeholders of the Safe Neonatal Project such as national maternal health experts, relevant government officials and medical staff. Thematic analysis was used to process and analyse the interview content in order to summarise the facilitators and barriers to implementing KMC.

RESULTS

KMC was accepted in the pilot areas but still faced certain challenges due to institutional regulation, resource provision and the perceptions of health staff, postpartum mothers and their families as well as COVID-19 prevention and control regulations. The facilitators identified were government officials and medical staff acceptance and the incorporation of KMC into routine clinical care. The barriers identified were a lack of dedicated funding and other resources, the present scope of health insurance and KMC cost-sharing mechanism, providers' knowledge and practical abilities, parental awareness, postpartum discomfort, fathers' inadequate involvement, and the impact from COVID-19.

CONCLUSION

The Safe Neonatal Project pilot experience indicated the feasibility of implementing KMC in more areas of China. Optimising institutional regulations, providing necessary supporting resources and enhancing education and training may help to refine the implementation and scale-up of KMC practice in China.

Determining resuscitation threshold for extremely preterm infants based on the survival rates without severe neurological injury

Background

Published guidelines on decision-making and resuscitation of extremely preterm infants primarily focus on high-income countries. For rapidly industrializing ones like China, there is a lack of population-based data for informing prenatal management and practice guidelines.

Methods

The Sino-northern Neonatal Network conducted a prospective multi-centre cohort study between 1 January 2018 and 31 December 2021. Infants with a gestational age (GA) between 22 (postnatal age in days = 0) and 28 (postnatal age in days = 6) admitted to 40 tertiary NICUs in northern China were included and evaluated for death or severe neurological injury before discharge.

Results

For all extremely preterm infants (n = 5838), the proportion of admission to the neonatal was 4.1% at 22-24 weeks, 27.2% at 25-26 weeks, and 75.2% at 27 and 28 weeks. Among 2228 infants admitted to the NICU, 216 (11.1%) were still elected for withdrawal of care (WIC) due to non-medical factors. Survival rates without severe neurological injury were 6.7% for infants at 22-23 weeks, 28.0% at 24 weeks, 56.7% at 24 weeks, 61.7% at 25 weeks, 79.9% at 26 weeks, and 84.5% at 27 and 28 weeks. Compared with traditional criterion at 28 weeks, the relative risk for death or severe neurological injury were 1.53 (95% confidence interval (CI) = 1.26-1.86) at 27 weeks, 2.32 (95% CI = 1.73-3.11) at 26 weeks, 3.62 (95% CI = 2.43-5.40) at 25 weeks, and 8.91 (95% CI = 4.69-16.96) at 24 weeks. The NICUs with higher proportion of WIC also had a higher rate of death or severe neurological injury after maximal intensive care (MIC).

Conclusions

Compared to the traditional threshold of 28 weeks, more infants received MIC after 25 weeks, leading to significant increases in survival rates without severe neurological injury. Therefore, the resuscitation threshold should be gradually adjusted from 28 to 25 weeks based on reliable capacity.

Registration

China Clinical Trials Registry. ID: ChiCTR1900025234.

Prenatal Exposure to Air Pollution and Pre-Labor Rupture of Membranes in a Prospective Cohort Study: The Role of Maternal Hemoglobin and Iron Supplementation

BACKGROUND

Exposure to air pollution in prenatal period is associated with prelabor rupture of membranes (PROM). However, the sensitive exposure time windows and the possible biological mechanisms underlying this association remain unclear.

OBJECTIVE

We aimed to identify the sensitive time windows of exposure to air pollution for PROM risk. Further, we examined whether maternal hemoglobin levels mediate the association between exposure to air pollution and PROM, as well as investigated the potential effect of iron supplementation on this association.

METHOD

From 2015 to 2021, 6,824 mother-newborn pairs were enrolled in the study from three hospitals in Hefei, China. We obtained air pollutant data [particulate matter (PM) with aerodynamic diameter ≤2.5μm (PM2.5), PM with aerodynamic diameter ≤10μm (PM10), sulfur dioxide (SO2), and carbon monoxide (CO)] from the Hefei City Ecology and Environment Bureau. Information on maternal hemoglobin levels, gestational anemia, iron supplementation, and PROM was obtained from medical records. Logistic regression models with distributed lags were used to identify the sensitive time window for the effect of prenatal exposure to air pollutant on PROM. Mediation analysis estimated the mediated effect of maternal hemoglobin in the third trimester, linking prenatal air pollution with PROM. Stratified analysis was used to investigate the potential effect of iron supplementation on PROM risk.

RESULTS

We found significant association between prenatal exposure to air pollution and increased PROM risk after adjusting for confounders, and the critical exposure windows of PM2.5, PM10, SO2 and CO were the 21th to 24th weeks of pregnancy. Every 10-μg/m3 increase in PM2.5 and PM10, 5-μg/m3 increase in SO2, and 0.1-mg/m3 increase in CO was associated with low maternal hemoglobin levels [-0.94g/L (95% confidence interval (CI): -1.15, -0.73), -1.31g/L (95% CI: -1.55, -1.07), -2.96g/L (95% CI: -3.32, -2.61), and -1.11g/L (95% CI: -1.31, -0.92), respectively] in the third trimester. The proportion of the association between air pollution and PROM risk mediated by hemoglobin levels was 20.61% [average mediation effect (95% CI): 0.02 (0.01, 0.05); average direct effect (95%): 0.08 (0.02, 0.14)]. The PROM risk associated with exposure to low-medium air pollution could be attenuated by maternal iron supplementation in women with gestational anemia.

CONCLUSIONS

Prenatal exposure to air pollution, especially in the 21st to 24th weeks of pregnancy, is associated with PROM risk, which is partly mediated by maternal hemoglobin levels. Iron supplementation in anemia pregnancies may have protective effects against PROM risk associated with exposure to low-medium air pollution. https://doi.org/10.1289/EHP11134.

Does recurrent gestational diabetes mellitus increase the risk of preterm birth? A population-based cohort study

AIMS

To investigate whether recurrent gestational diabetes mellitus (GDM) is associated with an increased risk of preterm birth.

METHODS

We conducted a prospective population-based cohort study covering all live singleton births born to nulliparous and multiparous mothers aged 20 years and older in Qingdao, from 2018 to 2020 (n = 105,528). Preterm birth (<37 gestational weeks) was classified into moderate preterm birth (32-36 weeks of gestation) and very preterm birth (<32 weeks). Logistic regression analysis was performed to estimate the risk and severity of prematurity in relation to parity among mothers with previous GDM, current GDM, and recurrent GDM (previous and current GDM), using mothers without GDM as the reference group. Z-test and ratio of odds ratios (ROR) were used to determine subgroup differences.

RESULTS

Maternal GDM increased the risk of preterm birth in both nullipara (OR_adj = 1.28, 95 %CI: 1.14-1.45) and multipara (OR_adj = 1.26, 95 %CI: 1.14-1.40). However, the risk of premature delivery in multiparous mothers with recurrent GDM and those with current GDM did not differ significantly, with a ROR of 0.89 (95 %CI: 0.71-1.12). The risk of recurrent GDM on preterm birth was most pronounced among multiparous mothers with pre-pregnancy BMI above 30 kg/m² (OR_adj = 2.18, 95 %CI: 1.25-3.82) as compared with those with current GDM alone (ROR = 2.20, 95 %CI: 1.07-4.52). The risk of GDM for moderate preterm birth was similar to that of overall preterm birth. In contrast, GDM was not associated with very preterm birth irrespective of parity (all P values > 0.05).

CONCLUSIONS

Maternal GDM increased the risk of preterm birth in nullipara and multipara, whereas recurrent GDM was not associated with a further increase in the risk of prematurity in multiparous mothers. Maternal GDM did not contribute to very preterm birth irrespective of parity. Our findings can be useful for facilitating more targeted preventive strategies for adverse pregnancy outcomes.

Time-varying effects are common in genetic control of gestational duration

Preterm birth is a major burden to neonatal health worldwide, determined in part by genetics. Recently, studies discovered several genes associated with this trait or its continuous equivalent - gestational duration. However, their effect timing, and thus clinical importance, is still unclear. Here, we use genotyping data of 31,000 births from the Norwegian Mother, Father and Child cohort (MoBa) to investigate different models of the genetic pregnancy "clock". We conduct genome-wide association studies using gestational duration or preterm birth, replicating known maternal associations and finding one new foetal variant. We illustrate how the interpretation of these results is complicated by the loss of power when dichotomizing. Using flexible survival models, we resolve this complexity and find that many of the known loci have time-varying effects, often stronger early in pregnancy. The overall polygenic control of birth timing appears to be shared in the term and preterm, but not very preterm periods, and exploratory results suggest involvement of the major histocompatibility complex genes in the latter. These findings show that the known gestational duration loci are clinically relevant, and should help design further experimental studies.

Chemical element concentrations in cord whole blood and the risk of preterm birth for pregnant women in Guangdong, China

Maternal exposure to chemical elements, including essential and non-essential elements, have been found to be associated with preterm births (PTB). However, few studies have measured element concentrations in cord whole blood, which reflects activity at the maternal-fetal interface and may be biologically associated with PTBs. In this study, we determined concentrations of 21 elements in cord whole blood and explored the associations between element concentrations and PTB in a nested case-control study within a birth cohort in Guangdong, China. Finally, 515 preterm infants and 595 full-term infants were included. We performed single-element and multi-element logistic regressions to evaluate linear relationships between element concentrations and PTB. According to the results of single-element models, most essential elements (including K, Ca, Si, Zn, Se, Sr and Fe) were negatively associated with PTB, while Cu, V, Co and Sn were positively associated with PTB. Of the non-essential elements, Sb, Tl, and U were positively associated with PTB, while Pb was negatively associated with PTB. The multi-element model results for most elements were similar, except that the association between Mg and PTB was shown to be significantly positive, and the association for Cu became much larger. A possible explanation is that the effects of Mg and Cu may be influenced by other elements. We performed restricted cubic spline (RCS) regressions and found significantly non-linear exposure-response relationships for Mg, Se, Sr, K and Sb, indicating that the effects of these elements on PTB are not simply detrimental or beneficial. We also examined the joint effect using a Bayesian kernel machine regression (BKMR) model and found the risk of PTB decreased significantly with element mixture concentration when lnC was larger than the median. Bivariate interaction analysis suggested antagonistic effects of Sb on Zn and Sr, which may be attributed to Sb negating the antioxidant capacity of Zn and Sr. This study provides additional evidence for the effect of element exposures on PTB, and will have implications for the prevention of excessive exposures or inappropriate element supplementation during pregnancy.

Exploring Effect of Postdischarge Developmental Support Program on Preterm Infant Neurodevelopment and BDNF Gene DNA Methylation

BACKGROUND

Although developmental supportive care is an effective approach to improve the long-term psychomotor and/or neurobehavioral function of preterm infants, very limited studies have focused on the impact of after-discharge developmental support. The underlying epigenetic changes are unclear.

PURPOSE

This study aimed to explore the preliminary effect of an evidence-based Postdischarge Developmental Support Program (PDSP) on preterm infant neurodevelopment and underlying epigenetic changes, including brain-derived neurotrophic factor (BDNF) gene-related DNA methylation and expression.

METHODS

In this randomized controlled pilot trial, the preterm infant-parent dyads were randomized into either the intervention group/PDSP group (n = 22) or the control group/usual care group (n = 22). The neurodevelopmental outcomes of preterm infants were measured by Ages & Stages Questionnaires. Urine BDNF concentration level was tested by the enzyme-linked immunosorbent assay. Infant saliva specimens were collected to analyze the methylation level of BDNF gene promoter I at pre- and postintervention test.

RESULTS

After PDSP intervention, the total neurodevelopmental and the 5 domain scores of the PDSP group were all significantly higher than those of the control group ( P < .05). The BDNF levels decreased significantly only within control group ( P = .01). The difference in BDNF concentration and methylation levels between groups was not statistically significant.

IMPLICATIONS FOR PRACTICE AND RESEARCH

Postdischarge Developmental Support Program may promote the neurodevelopment of preterm infants but has no effect on BDNF's expression and gene methylation level at 3 months of corrected age. The epigenetic mechanism of PDSP needs further study using a larger sample and longer follow-up.

The causal and independent effect of ozone exposure during pregnancy on the risk of preterm birth: Evidence from northern China

The concentration of ozone (O₃) in the environment is gradually increasing, but there are limited reports on the exposure to O₃ during pregnancy on the risk of adverse birth outcomes. Our study aimed to examine the causal and independent effect of O₃ exposure during pregnancy on the risk of preterm birth (PTB) and to identify the critical window. Based on the baseline population of the birth cohort in Jinan, northern China, we obtained the individual exposure for each subject during pregnancy of ambient 8-h moving average O₃ through the inverse distance weighting model. The effect of O₃ exposure during pregnancy on PTB was evaluated through the time-dependent Cox proportional-hazard models. And we assessed the causal relationship by controlling unknown confounding factors using the instrumental variable (IV) analysis, estimated the independent effect by principal component analysis, and identified the critical window period of exposure through the distributed lag model. Among 6501 subjects, 285 mothers delivered prematurely. The median (IQR) of O₃ concentration during pregnancy was 109.51 (23.54) μg/m³. The high level of O₃ exposure (>173.64 μg/m³) increased the risk of PTB, with HR of 1.92 (95% CI: 1.38-2.66). Furthermore, the HR (95% CI) of the O₃ estimated value calculated by the IV (wind speed) on the risk of PTB was 2.63 (1.41-4.88). In addition, the high level of O₃ exposure was associated with the risk of PTB in the 13th-18th gestational weeks. Therefore, the high level of O₃ exposure during pregnancy may independently increase the risk of PTB, which may be a causal effect. The 13th to 18th week of gestation is a critical window for preventing this risk.

Current epidemiology and factors contributing to postnatal growth restriction in very preterm infants in China

BACKGROUND

Postnatal growth restriction (PGR) is common in very preterm infants (VPIs) and is associated with adverse short and long-term developmental outcomes. Postnatal growth status for VPIs in middle- or low-income countries remains unclear.

AIMS

To evaluate PGR in VPIs and identify maternal and neonatal factors, clinical practice, and major neonatal morbidities associated with PGR in China.

STUDY DESIGN

Prospective cohort study.

SUBJECTS

We included 6085 infants born at <32 weeks gestation who were admitted at 57 hospitals in the Chinese Neonatal Network in 2019.

OUTCOME MEASURES

Birth and discharge weights were converted to age-specific Z-scores. PGR was defined as a decrease in weight z-score from birth to discharge >2.

RESULTS

The overall incidence of PGR was 19.9 %. The mean (standard deviation [SD]) weight Z-score was 0.12 (0.78) at birth and decreased to -1.36 (0.98) at discharge. About 4.0 % of VPIs were small for gestational age (SGA) at birth and 25.5 % of SGA infants had PGR. The incidence of PGR increased with decreasing gestational age except in the SGA subgroup. Each 1-unit increase in birthweight Z-score was associated with a 1.49-fold increased risk for PGR. Late initiation of enteral feeds and late achievement of full enteral feeds were positively associated with PGR. The common morbidities that influenced PGR were necrotizing enterocolitis ≥ stage II, patent ductus arteriosus requiring medical or surgical treatment, sepsis, bronchopulmonary dysplasia, and respiratory distress syndrome requiring surfactants.

CONCLUSION

Nearly one fifth of VPIs were PGR, and one fourth of SGA had PGR, which warranted further study to investigate underlying causes by which to improve postnatal growth in very preterm infants in future.

Ethnic differences in preterm birth in Southwest China, 2014-2018: A population-based observational study

Objective

Preterm birth is a major healthcare problem and has been rising gradually in the past three decades in China. Yet the ethnic differences in the rates and distributions of preterm birth remain largely unknown in China. This study used data from Yunnan, a multiethnic province, to explore the differences in preterm birth across ethnicities.

Methods

A population-based observational study was conducted based on data from the National Free Preconception Health Examination Project in rural Yunnan from Jan 1, 2014 to Dec 31, 2018. Pregnancies with at least one livebirth were included in this study. We estimated the rates and 95% confidence intervals (CIs) of overall preterm birth (born &lt; 37 weeks’ gestation), moderate to late preterm birth (born between 32 and &lt;37 weeks’ gestation), very preterm birth (born between 28 and 31 weeks’ gestation), and extremely preterm birth (born &lt; 28 weeks’ gestation) across maternal ethnicity and compared them using log-binomial regressions. Multivariable log-binomial regressions were used to assess the association between maternal ethnicity and preterm birth with adjustment for potential confounders, including year of delivery, maternal age at delivery, education, occupation, pre-pregnancy body mass index, history of chronic disease, history of preterm birth, smoking and drinking alcohol during early pregnancy, and parity and multiple pregnancy of current pregnancy.

Results

Among 195,325 women who delivered at least one live baby, 7.90% (95% CI, 7.78–8.02%) were born preterm. The rates of moderate to late preterm birth, very preterm birth, and extremely preterm birth were 6.20% (95% CI, 6.09–6.30%), 1.18% (95% CI, 1.13–1.23%), and 0.52% (95% CI, 0.49–0.56%), respectively. The rates of overall preterm birth, moderate to late preterm birth, very preterm birth, and extremely preterm birth differed across maternal ethnicity. The preterm birth rates in Dai (10.73%), Miao (13.23%), Lisu (12.64%), Zhuang (11.77%), Wa (10.52%), and Lagu (12.34%) women were significantly higher than that in Han women, and the adjusted relative risks were 1.45 [95% CI, 1.36, 1.54], 1.74 (95% CI, 1.62, 1.86), 1.60 (95% CI, 1.47, 1.75), 1.60 (95% CI, 1.46, 1.75), 1.40 (95% CI, 1.22, 1.60), and 1.67 (95% CI, 1.50, 1.87) respectively. There was no difference in preterm birth rate between Han women and Hani, Bai, or Hui women.

Conclusion

This study found notable differences in the rates of preterm birth and its sub-categories across maternal ethnicities, which were especially higher in ethnic minority women. The findings suggest that greater efforts to reduce ethnic inequalities in preterm birth. Future studies are warranted to understand the drivers of ethnic inequalities in preterm birth in China.

Low Fetal Fraction of Cell Free DNA at Non-Invasive Prenatal Screening Increases the Subsequent Risk of Preterm Birth in Uncomplicated Singleton Pregnancy

Objective

To examine the association between low fetal fraction (FF) of cell free DNA determined at non-invasive prenatal screening (NIPS) and the subsequent risk of preterm birth in uncomplicated singleton pregnancy.

Methods

We retrospectively interrogated NIPS System and hospitalization records from April 2018 to August 2019 and obtained results from 1521 consecutive and uncomplicated women with singleton pregnancy in which plasma FF of cell free DNA at NIPS had been investigated together with birth outcomes. We examined the association between FF and preterm birth (PTB) by regression analysis.

Results

The incidence of preterm birth, low birthweight, and macrosomia in the study population was 5.06%, 2.89%, and 7.17%, respectively. FF at NIPS in the second to fourth quartiles (8.40-11.07, 11.08-13.70, and >13.70%, respectively) was associated with higher gestational age at delivery relative to the lowest quartile (<8.40%), with estimated mean increases of 0.27 weeks (95% CI: 0.05-0.49), 0.29 weeks (95% CI: 0.06-0.51), and 0.28 weeks (95% CI: 0.05-0.51), respectively (P for trend = 0.027). Low FF (< the 5^th percentile) was associated with an increased risk of PTB (adjusted OR: 2.23, 95% CI: 1.01-4.98, P = 0.047) compared to normal FF (≥ the 5^th and ≤ the 95^th percentiles). In addition, when compared to women with normal FF and body mass index (BMI) <25 at NIPS, the risk of early PTB (< 34 weeks gestation) was remarkably significantly higher among those with low FF and BMI ≥25 (adjusted OR: 6.29, 95% CI: 1.71-23.15, P = 0.006).

Conclusion

Our study supports the association of low FF at NIPS with PTB (especially early PTB) for uncomplicated singleton pregnancy.

[Influence of the coronavirus disease 2019 pandemic on maternal breastfeeding for very low birth weight infants]

OBJECTIVES

To investigate the changes in the rate and volume of mother's own milk (MOM) feeding for very low birth weight infants (VLBWIs) hospitalized during the prevention and control of the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

A retrospective analysis was performed on the medical data of the VLBWIs with a gestational age of <32 weeks who were born and admitted to the Neonatal Intensive Care Unit of Nanjing Maternal and Child Health Hospital from January 2019 to December 2020. The changes in the rate and volume of MOM feeding for VLBWIs during hospitalization were examined.

RESULTS

A total of 301 VLBWIs were enrolled. According to the timing of COVID-19 outbreak, these infants were divided into a pre-CIVID-19 group with 205 VLBWIs and a post-COVID-19 group with 96 VLBWIs. Compared with the pre-CIVID-19 group, the post-COVID-19 group had a significantly lower rate of MOM feeding within 28 days after birth and during hospitalization (P<0.05), a significantly lower volume of MOM feeding within 0-7 days, 0-14 days, and 0-28 days after birth (P<0.05), and significantly higher incidence rates of moderate-to-severe bronchopulmonary dysplasia and feeding intolerance (P<0.05).

CONCLUSIONS

The COVID-19 pandemic has a significant impact on MOM feeding for VLBWIs, and there are significant reductions in the rate and volume of MOM feeding for VLBWIs within 28 days after birth, as well as a significant reduction in the rate of MOM feeding during hospitalization.

Blood pressure trajectories during pregnancy and preterm delivery: A prospective cohort study in China

Women's blood pressure (BP) changes throughout pregnancy. The effect of BP trajectories on preterm delivery is not clear. The authors aim to evaluate the association between maternal BP trajectories during pregnancy and preterm delivery. The authors studied pregnant women included in the Born in Guangzhou Cohort Study in China between February 2012 and June 2016. Maternal BP was measured at antenatal visits between 13 and 40 gestational weeks, and gestational age of delivery data was collected. The authors used linear mixed models to capture the BP trajectories of women with term, and spontaneous and iatrogenic preterm delivery. BP trajectories of women with various gestational lengths (34, 35, 36, 37, 38, 39, 40 weeks) were compared. Of the 17 426 women included in the analysis, 618 (3.55%) had spontaneous preterm delivery; 158 (.91%) had iatrogenic preterm delivery; and 16 650 (95.55%) women delivered at term. The BP trajectories were all J‐shaped curves for different delivery types. Women with iatrogenic preterm delivery had the highest mean BP from 13 weeks till delivery, followed by those with spontaneous preterm delivery and term delivery (p < .001). Trajectory analysis stratified by maternal parity showed similar results for nulliparous and multiparous women. Excluding women with pre‐eclampsia and gestational hypertension (GH) significantly attenuated the aforementioned association. Also, women with shorter gestational length tend to have higher BP trajectories during pregnancy. In conclusion, Women with spontaneous preterm delivery have a higher BP from 13 weeks till delivery than women with term delivery, while women with iatrogenic preterm delivery have the highest BP.

Association of maternal obesity with preterm birth phenotype and mediation effects of gestational diabetes mellitus and preeclampsia: a prospective cohort study

BACKGROUND

The association between maternal obesity and preterm birth remains controversial and inconclusive, and the effects of gestational diabetes mellitus (GDM) and preeclampsia (PE) on the relationship between obesity and preterm birth have not been studied. We aimed to clarify the relationship between prepregnancy body mass index (BMI) and the phenotypes of preterm birth and evaluate the mediation effects of GDM and PE on the relationship between prepregnancy BMI and preterm birth.

METHODS

We conducted a prospective cohort study of 43,056 women with live singleton births from 2017 through 2019. According to the WHO International Classification, BMI was classified as underweight (BMI < 18.5 kg/m2), normal weight (BMI 18.5-25 kg/m2), overweight (BMI 25-30 kg/m2) and obese (BMI ≥30 kg/m2). Preterm birth was defined as gestational age less than 37 weeks (extremely, < 28 weeks; very, 28-31 weeks; and moderately, 32-36 weeks). The clinical phenotypes of preterm birth included spontaneous preterm birth (spontaneous preterm labor and premature rupture of the membranes) and medically indicated preterm birth. We further analyzed preterm births with GDM or PE. Multivariable logistic regression analysis and causal mediation analysis were performed.

RESULTS

Risks of extremely, very, and moderately preterm birth increased with BMI, and the highest risk was observed for obese women with extremely preterm birth (OR 3.43, 95% CI 1.07-10.97). Maternal obesity was significantly associated with spontaneous preterm labor (OR 1.98; 95% CI 1.13-3.47), premature rupture of the membranes (OR 2.04; 95% CI 1.08-3.86) and medically indicated preterm birth (OR 2.05; 95% CI 1.25-3.37). GDM and PE mediated 13.41 and 36.66% of the effect of obesity on preterm birth, respectively. GDM mediated 32.80% of the effect of obesity on spontaneous preterm labor and PE mediated 64.31% of the effect of obesity on medically indicated preterm birth.

CONCLUSIONS

Maternal prepregnancy obesity was associated with all phenotypes of preterm birth, and the highest risks were extremely preterm birth and medically indicated preterm birth. GDM and PE partially mediated the association between obesity and preterm birth.

Preterm delivery rate in China: a systematic review and meta-analysis

BACKGROUND

Preterm delivery rate is a crucial public health indicator, yet reliable statistic is currently not available in China. In this systematic review and meta-analysis, we aimed to review studies on preterm delivery rate in China, explore sources of heterogeneity, and estimate the preterm delivery rate in China.

METHODS

Published studies on preterm delivery rate in China since 2010 were electronically searched from PubMed, Embase, Web of Science, China National Knowledge Infrastructure, China Science and Technology Journal Database, and Wanfang Database, and complemented by manual search. Study selection, data extraction, and quality and bias assessment (using the Joanna Briggs Institute Critical Appraisal Checklist) were conducted by two reviewers independently. Random-effects meta-analysis was performed to estimate the pooled preterm delivery rate, and prespecified stratified analysis was conducted to explore sources of heterogeneity.

RESULTS

The database search returned 4494 articles and manual search identified 10 additional studies. In total, 162 studies were eligible, of which 124 were hospital-based and 38 population-based. The pooled preterm delivery rate of hospital-based studies (7.2%; 95% CI: 6.9% to 7.6%) was significantly higher than that of population-based studies (4.9%; 95% CI: 4.5% to 5.4%) (P for subgroup difference < 0.001). Among population-based studies, the rate tended to differ by geography (P for subgroup difference = 0.07): 5.3% for Eastern, 4.6% for Central, and 3.8% for Western.

CONCLUSIONS

According to population-based studies, the preterm delivery rate in China is around 5%. This rate is substantially lower than estimates from hospital-based studies or estimates from a combination of both hospital-based and population-based studies as having been done in previous studies.

Preterm delivery rate in China: a systematic review and meta-analysis

BACKGROUND

Preterm delivery rate is a crucial public health indicator, yet reliable statistic is currently not available in China. In this systematic review and meta-analysis, we aimed to review studies on preterm delivery rate in China, explore sources of heterogeneity, and estimate the preterm delivery rate in China.

METHODS

Published studies on preterm delivery rate in China since 2010 were electronically searched from PubMed, Embase, Web of Science, China National Knowledge Infrastructure, China Science and Technology Journal Database, and Wanfang Database, and complemented by manual search. Study selection, data extraction, and quality and bias assessment (using the Joanna Briggs Institute Critical Appraisal Checklist) were conducted by two reviewers independently. Random-effects meta-analysis was performed to estimate the pooled preterm delivery rate, and prespecified stratified analysis was conducted to explore sources of heterogeneity.

RESULTS

The database search returned 4494 articles and manual search identified 10 additional studies. In total, 162 studies were eligible, of which 124 were hospital-based and 38 population-based. The pooled preterm delivery rate of hospital-based studies (7.2%; 95% CI: 6.9% to 7.6%) was significantly higher than that of population-based studies (4.9%; 95% CI: 4.5% to 5.4%) (P for subgroup difference < 0.001). Among population-based studies, the rate tended to differ by geography (P for subgroup difference = 0.07): 5.3% for Eastern, 4.6% for Central, and 3.8% for Western.

CONCLUSIONS

According to population-based studies, the preterm delivery rate in China is around 5%. This rate is substantially lower than estimates from hospital-based studies or estimates from a combination of both hospital-based and population-based studies as having been done in previous studies.

Effects of greenness on preterm birth: A national longitudinal study of 3.7 million singleton births

Exposure to greenness may lead to a wide range of beneficial health outcomes. However, the effects of greenness on preterm birth (PTB) are inconsistent, and limited studies have focused on the subcategories of PTB. A total of 3,751,672 singleton births from a national birth cohort in mainland China were included in this study. Greenness was estimated using the satellite-based Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index with 500-m and 1,000-m buffers around participants’ addresses. The subcategories of PTB (20–36 weeks) included extremely PTB (EPTB, 20–27 weeks), very PTB (VPTB, 28–31 week), and moderate-to-late PTB (MPTB, 32–36 weeks). Gestational age (GA) was included as another birth outcome. We used logistic regression models and multiple linear regression models to analyze these associations throughout the entire pregnancy. We found inverse associations between greenness and PTB and positive associations between greenness and GA. Specifically, an increase of 0.1 NDVI exposure within a 500-m buffer throughout the entire pregnancy was significantly associated with decreases in PTB (odds ratio [OR], 0.930; 95% confidence interval [CI], 0.927–0.932), EPTB (OR, 0.820; 95% CI, 0.801–0.839), VPTB (OR, 0.913; 95% CI, 0.908–0.919), MPTB (OR, 0.934; 95% CI, 0.931–0.936), and an increase in GA (β = 0.050; 95% CI, 0.049–0.051 weeks). These results suggest the potential protective effects of greenness on PTB and its subcategories: MPTB, VPTB, and EPTB in China.

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A national study with 3.7 million births on greenness-PTB in China

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Higher greenness was associated with lower risks of PTB and its subcategories

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PTB of shorter gestational weeks may benefit more from greenness exposure

Association of China's two-child policy with changes in number of births and birth defects rate, 2008-2017

Background

In October 2015, China’s one-child policy was universally replaced by a so-called two-child policy. This study investigated the association between the enactment of the new policy and changes in the number of births, and health-related birth outcomes.

Methods

We used difference-in-difference model to analyse the birth record data in Pudong New Area, Shanghai.The design is descriptive before-and-after comparative study.

Results

The data covered three policy periods: the one-child policy period (January 2008 to November 2014); the partial two-child policy period (December 2014 to June 2016); the universal two-child policy period (July 2016 to December 2017). There was an estimate of 7656 additional births during the 18 months of the implementation of the universal two-child policy. The trend of monthly percentage of births to mothers aged ≥35 increased by 0.24 percentage points (95% confidence interval 0.19 to 0.28, p < 0.001) during the same period. Being a baby boy, preterm birth, low birth weight, parents with lower educational attainment, and assisted delivery were associated with a higher risk of birth defects.

Conclusions

The universal two-child policy was associated with an increase in the number of births and maternal age. Preterm birth, low birth weight, and assisted delivery were associated with a higher risk of birth defects, which suggested that these infants needed additional attention in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12839-0.

Preterm birth update in Australasia: A report of the international symposium of Preterm Birth International Collaborative-Australasia branch

Preterm birth (PTB) is one of the most important problems that pose dilemmas for both the obstetrician and neonatologist, placing a heavy burden psychologically and financially on the families involved, and triggering high socio-economic costs to the public healthcare. The rate of PTB in Asian countries has been ranked at top globally. To reduce the PTB rate, to promote the prevention and intervention for PTB, and to better understand the pathophysiology underlying PTB, the Preterm Birth International Collaborative Australia branch (PREBIC-AA) was launched in 2017. A series scientific activities including organizing annual research symposiums has been planned and organized among Australasian countries. Here we briefly updated the current progress in clinical management and translational research on PTB in Australasian countries that have been participated in PREBIC-AA.

Discharge against medical advice among infants with 24-31 weeks' gestation admitted to Chinese neonatal intensive care units: A multicenter cohort study

BACKGROUND

Previous studies demonstrated high rates of discharge against medical advice (DAMA) among very preterm infants (VPIs) in China.

OBJECTIVES

The aim of this study was to investigate the concurrent incidence, variation, and predictors of DAMA, along with the effect of DAMA on mortality of VPIs in China using data from the Chinese Neonatal Network (CHNN).

METHODS

All infants born at 24-31 completed weeks' gestation and admitted to 57 CHNN neonatal intensive care units (NICUs) in 2019 were included for this cohort study, excluding infants with major congenital anomalies. Patient information was prospectively collected using the CHNN database. Multivariable log-linear regression analysis was used to assess the association of perinatal factors and DAMA.

RESULTS

A total of 9,442 infants born at 24-31 completed weeks' gestation and admitted to 57 CHNN participating sites in 2019 were included in the study. Overall, 1,341 infants (14.2%) were discharged against medical advice. Rates of DAMA decreased with increasing gestational age (GA), and infants with lower GA were discharged earlier. DAMA infants had significantly higher rates of necrotizing enterocolitis, severe brain impairment, and bronchopulmonary dysplasia than non-DAMA infants. A total of 58.2% DAMA infants were predicted to die after discharge. The attributable risk percentage of mortality among DAMA infants was 92.4%. Younger maternal age, lower gestational age, small for gestational age, and Apgar score ≤3 at 5 min were independently associated with an increased risk of DAMA, while infants with antenatal steroids were less likely to be DAMA.

CONCLUSION

The rate of DAMA in preterm infants between 24 and 31 weeks' gestation remained high in China with a significant impact on the mortality rates. Continuous efforts to reduce DAMA would result in substantial improvement of outcomes for VPIs in China.

Associations between hair levels of trace elements and the risk of preterm birth among pregnant Wwomen: A prospective nested case-control study in Beijing Birth Cohort (BBC), China

Trace elements have various physiochemical functions in humans and are associated with the occurrence of preterm birth (PB). However, their mixed effects on PB risk have rarely been studied. We aimed to investigate the associations between hair levels of trace elements and PB risk among pregnant women. A nested case-control study with a prospective cohort was conducted in Beijing City, China. We included 82 women who had a PB [total PB (tPB)] as cases [including 40 with a spontaneous PB (SPB)] and 415 who had a term delivery as controls. Hair levels of the concerned trace elements were measured including endocrine disrupting metal(loid)s [EDMs; lead, mercury (Hg), arsenic, and cadmium] and nutritional trace metal(loid)s [NTMs; zinc (Zn), iron (Fe), copper, and selenium]. Logistic regression analysis was performed to estimate the odds ratios (ORs) for PB. Bayesian kernel machine regression (BKMR) was used to assess the associations between mixed exposure to the trace elements and PB risk. Significantly lower maternal hair concentrations of Zn and Fe were observed in the SPB cases than in the controls, whereas no differences for the other trace elements. Single-element modeling results suggested second-quartile Hg maternal hair concentrations, third-quartile Zn concentrations, and fourth-quartile Fe concentrations were associated with a reduced risk of tPB with adjusted ORs of 0.43 [95% confidence interval (CI): 0.21-0.87], 0.38 (95% CI: 0.18-0.82), and 0.48 (95% CI: 0.24-0.98), respectively, compared to first-quartile values. Similar results were obtained for SPB. According to the BKMR models, hair NTMs were significantly, monotonously, and inversely associated with the risk of SPB, after controlling for covariates and levels of the four EDMs. Fe and Zn contributed the most strongly to the association. We concluded that maternal higher levels of NTMs, especially Fe and Zn, may reduce the risk of PB.

Preterm neonatal mortality in China during 2009-2018: A retrospective study

In this retrospective analysis, we aimed to analyze the epidemic characteristics of neonatal mortality due to preterm birth at 28-36 weeks gestation in different regions from 2009 to 2018. Data were obtained from China's Under-5 Child Mortality Surveillance System (U5CMSS). The χ2 trend test, Poisson regression and the Cochran-Mantel-Haenszel method were used in this study. We found that 51.3%, 42.0% and 44.5% of neonate deaths were preterm infants, and immaturity was mainly attributed to 60.1%, 64.1% and 69.5% of these deaths, in the eastern, central and western regions, respectively. The preterm neonatal mortality rate due to immaturity dropped from 149.2, 216.5 and 339.5 in 2009 to 47.4, 83.8 and 170.1 per 100 000 live births in 2018, giving an average annual decline rate of 12.1%, 11.6% and 6.3% in the eastern, central and western regions, respectively, during the studying period. The relative risk of preterm neonatal mortality due to immaturity were 1.3 and 2.3 for the central regions and western regions in 2009-2010, ascending to 2.2 and 3.9 in 2017-2018. The proportion of preterm neonatal deaths with a gestational age <32 weeks was highest among the eastern region. There were significantly more preterm neonatal infants who were not delivered at medical institutions in the western region than in the eastern and central regions. The preterm infant, especially with gestational age <32 weeks, should receive the most attention through enhanced policies and programs to improve child survival. Priority interventions should be region-specific, depending on the availability of economic and healthcare resources.

Prediction of Preterm Using Time Series Technology Based Machine Learning: Retrospective Cohort Study (Preprint)

Background

Objective

Methods

Results

Conclusions

Effects of Dietary Patterns during Pregnancy on Preterm Birth: A Birth Cohort Study in Shanghai

The objective of this study was to analyse representative dietary patterns during pregnancy in Shanghai and explore the effects of dietary patterns during pregnancy on preterm birth. Data were derived from the ‘Iodine Status in Pregnancy and Offspring Health Cohort’ (ISPOHC) study. Multistage, stratified random sampling was used to select survey participants from 16 districts in Shanghai, which were divided into five sampling areas; 40–70 pregnant women were selected from each area. A total of 4361 pregnant women and their offspring were involved in the study. The male-to-female ratio of the babies was 1.04:1, and the incidence of single preterm birth was 4.2%. Three dietary patterns were extracted by factor analysis: a ‘Vegetarian Pattern’, an ‘Animal Food Pattern’ (AFP), and a ‘Dairy and Egg Pattern’. These patterns explained 40.513% of the variance in dietary intake. Binary logistic regression, which was used to analyse the association between birth outcomes and scores measuring maternal dietary patterns, found only the AFP was a significant risk factor for preterm birth. Higher AFP scores were positively associated with preterm birth (Q2 vs. Q1 OR = 1.487, 95% CI: 1.002–2.207; Q3 vs. Q1 OR = 1.885, 95% CI: 1.291–2.754). After adjusting for other potential contributors, a higher AFP score was still a significant risk factor for preterm birth (Q2 vs. Q1 OR = 1.470, 95% CI: 0.990–2.183; Q3 vs. Q1 OR = 1.899, 95% CI: 1.299–2.776). The incidence of preterm birth was 4.2%. A higher score of AFP was significantly associated with a higher risk of preterm birth. The animal food intake of pregnant women should be reasonably consumed during pregnancy.

Risk Factors Associated With Renal and Urinary Tract Anomalies Delineated by an Ultrasound Screening Program in Infants

OBJECTIVE

To evaluate the value of ultrasound screening for congenital anomalies of the kidney and urinary tract (CAKUT) during the early postnatal period.

METHODS

This is a prospective study that enrolled all neonates born from August 2019 to July 2020 at one medical center. Postnatal ultrasound screening was conducted in all neonates at 1, 3, and 6 months old, respectively. Information on antenatal detection and pregnancy was collected. We performed logistic regression analyses and established a predictive model to assess the potential risk factors of abnormal ultrasound screening results.

RESULTS

Postnatal ultrasound scanning in 4,877 infants identified 268 cases (5.5%) of anomalies of kidney and urinary tract by primary screening and 92 cases (1.9%) by tertiary screening. A specific diagnosis was identified in 47 cases within the 6-month screening and follow-up program. Logistic regression revealed that preterm birth, oligohydramnios, antenatal ultrasound screening anomalies, and gestational hypothyroidism were independent risk factors for the early detection of CAKUT by postnatal ultrasound screening. The above factors were adopted to develop a predictive model that showed good calibration in predicting ultrasound findings of CAKUT. Decision curve analysis demonstrated good clinical utility.

CONCLUSIONS

Postnatal ultrasound screening should be conducted in infants with risk factors associated with CAKUT. Further study on prenatal and fetal factors could help establish the predictive model for the early detection of CAKUT.

Customised, individually made total knee arthroplasty shows promising 1-year clinical and patient reported outcomes

INTRODUCTION

Customised individually made (CIM) implants for total knee arthroplasty (TKA) were introduced about 10 years ago. These implants aim to reduce the risk of prosthesis-related issues resulting from anthropometric differences between different knees. The purpose of this study was to analyse the short-term clinical outcome and patient reported outcome measures (PROMs) of a specific CIM implant, the ORIGIN^® knee replacement system (Symbios, Yverdon-les-Bains, Switzerland), which was introduced in 2018.

MATERIALS AND METHODS

This is a prospective cohort study of patients undergoing primary posterior-stabilised (PS) CIM TKA using the specific ORIGIN^® knee replacement system, (Symbios, Yverdon-les-Bains, Switzerland). TKAs were performed from February 2019 to October 2020. Data was collected preoperatively and postoperatively at 4 and 12 months. Outcome measures included the objective part of the Knee Society Score (KSS) with the range of motion (ROM) and the following PROMs: the Knee injury and Osteoarthritis Outcome Score (KOOS), the Forgotten Joint Score (FJS-12), the EuroQol, five dimensions, three levels (EQ-5D-3L) with the EuroQol visual analogue scale (EQ-VAS) and patient satisfaction. Differences in pre- to preoperative data were assessed with paired sample t tests. A p value < 0.05 was considered significant.

RESULTS

Twenty-five CIM TKA (20 patients, 8 female) were included. The mean age at surgery was 66 years (SD, 6.9). At 4 and 12 months, significant improvements in the KSS (p < 0.001), the ROM (p < 0.001), all KOOS subscales (p < 0.001), the FJS (p < 0.001) and the EQ-5D-3L (p < 0.026) were found. Satisfaction rate was 91% and 88% at 4 and 12 months, respectively. Intraoperative complications did not occur and no revision surgeries were undertaken.

CONCLUSIONS

The present study demonstrated significant improvements in the KSS and specific PROMs 1 year after CIM TKA. This study suggests that CIM TKA is a safe and suitable option, which can yield good clinical outcome and PROMs at least during short-term follow-up.