Temporal trends in the birth rates and perinatal mortality of twins: A population-based study in China

Association between risk of mortality among children and twin birth in India: an econometric analysis of live births between 1993-2021

Background

Twin births present unique challenges for child survival, particularly in low- and middle-income countries. Despite the high burden of global child mortality, there has been no comprehensive assessment of twin births and deaths in India. We analysed the trends and patterns in twin births and deaths in India between 1993 and 2021, examining mortality risks across different phases of early childhood, including the late neonatal phase.

Methods

We analysed data on 659 175 births from five rounds of India's National Family Health Survey (NFHS) (1992-93 to 2019-21). We calculated age-specific mortality rates using a synthetic cohort life table approach for early neonatal (0-7 days), late neonatal (8-28 days), post-neonatal (29 days to 11 months), and child (12-59 months) periods. The analysis employed logistic regression models (both adjusted and unadjusted) to estimate phase-specific mortality risks and coarsened exact matching to establish causal relationships while adjusting for demographic and socioeconomic covariates.

Results

Twinning rates in India increased from 0.9% in 1992-93 to 1.5% in 2019-21. Despite this small share in births, twins accounted for 7.7% of under-five deaths in 2019-21. Twin under-five mortality rate was 179.8 (95% confidence interval (CI) = 162.2, 197.4) per 1000 live births in 2019-21, declining from 447.5 (95% CI = 405.6, 489.3) in 1992-93. Twins faced 7.5 times higher risk of early neonatal death and 10 times higher risk of late neonatal death compared to singletons. Twins from the poorest wealth quintile experienced 9.8 (95% CI = 8.43, 11.44) times higher early neonatal mortality risk compared to those from the highest quintile. The coarsened exact matching analysis confirmed twin birth as an independent risk factor for neonatal and infant mortality.

Conclusions

Despite general improvements in child survival, twin mortality rates continue to be high, particularly during the neonatal period. The persistent socioeconomic gradient in twin survival necessitates strengthening health care delivery for vulnerable populations. Establishing twin registries and including twin mortality in global monitoring frameworks could accelerate progress toward achieving Sustainable Development Goal targets for child survival.

Prenatal exposure to multiple air pollutants and risks of preterm birth and low birth weight in twins: A comparison between natural conception and medically assisted reproduction

Exposure to air pollution has been linked to higher risks of adverse pregnancy outcomes. However, evidence from twin pregnancies is limited, and differences between natural conception (NC) and medically assisted reproduction (MAR) remain unexplored. This study enrolled 935 twin pairs in Wuxi, China, from 2017 to 2022. A high spatiotemporal resolution prediction model was used to assess prenatal exposure to air pollutants, including PM2.5, PM10, SO2, NO2, CO, and O3. Associations of prenatal air pollution exposure with preterm birth (PTB), low birth weight (LBW), and low birth weight preterm birth (LBWPT) were analyzed using generalized linear models. The prevalence of PTB, LBW, and LBWPT among the twin pairs was 68.0 %, 72.4 %, and 57.5 %, respectively. Prenatal exposures to PM2.5, PM10, SO2, and CO were significantly associated with increased risks of PTB, LBW, and LBWPT. Subgroup analyses revealed increased risks in the MAR group (SO2) for PTB and LBWPT, the NC group (CO) for LBW, and twins born in winter/spring (PM2.5, PM10, SO2) for PTB and LBWPT. Our findings underscore the importance of tailoring preventive measures to MAR-conceived twins, NC twins, and those born in winter/spring to better protect against the adverse effects of prenatal air pollution exposure.

Effect of gestational weight gain on adverse birth outcomes in twin pregnancies: a prospective cohort study in Chinese women

BACKGROUND

Gestational weight gain (GWG) plays a critical role in determining birth outcomes, especially in twin pregnancies. However, the association between GWG and adverse birth outcomes in twin pregnancies remains inconclusive. This study aims to define GWG according to different classification criteria and explore their associations with adverse birth outcomes in twin pregnancies.

METHODS

This was a prospective cohort study that included 1,029 twin pregnant women recruited from Qingdao Women and Children's Hospital between September 2018 and December 2020. Participants were categorized into insufficient, adequate, and excessive GWG groups using both the interquartile range (P25-P75) method and the Institute of Medicine (IOM) criteria. Logistic regression models were employed to assess the associations between GWG and adverse birth outcomes, including preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA).

RESULTS

According to the interquartile range method, women in the insufficient GWG group had a significantly increased risk of PTB (OR: 2.13, 95% CI: 1.55-2.94), LBW (OR: 2.01, 95% CI: 1.33-3.05), and SGA (OR: 1.62, 95% CI: 1.03-2.54) compared to adequate GWG group. In contrast, the excessive GWG group was associated with a reduced risk of LBW (OR: 0.64, 95% CI: 0.45-0.92) and SGA (OR: 0.51, 95% CI: 0.28-0.91) after adjusting for potential confounders. Similar trends were observed using the IOM criteria, with a significantly increased risk of PTB and LBW in twin pregnant women with insufficient GWG and a reduced risk of SGA with excessive GWG.

CONCLUSIONS

Achieving an appropriate level of weight gain during pregnancy is essential to reduce the risk of adverse birth outcomes in women with twin pregnancies.

The effectiveness of ultrasound-indicated cerclage for the reduction of extreme preterm birth in twin pregnancies with a short cervix: a systematic review and meta-analysis

OBJECTIVE

This study aimed to evaluate the effectiveness of cervical cerclage in women with a twin pregnancy and a midpregnancy asymptomatic short cervix (≤25 mm), in preventing preterm birth and improving neonatal outcomes.

DATA SOURCES

Systematic searches were conducted in MEDLINE, Embase, Web of Science, Scopus, and Cochrane Library up to April 17, 2023, updated in September and February 2024.

STUDY ELIGIBILITY CRITERIA

Included were randomized controlled trials, cohort studies, and case-control studies comparing cerclage with expectant management in twin pregnancies and an asymptomatic short cervix (≤25 mm).

METHODS

Risk of bias was assessed using the Newcastle-Ottawa Quality Assessment Scale and the Risk of Bias 2 tool. Data were analyzed using RevMan 5.4 using a random-effects model.

RESULTS

Three randomized controlled trials and 13 cohort studies, involving 696 cerclage patients and 595 controls, were analyzed. Combined randomized controlled trial findings (N=49) found no significant difference in preterm birth occurrence after adjustment for preterm birth history and gestational age. Neonates from cerclage-treated mothers exhibited significantly higher rates of respiratory distress syndrome (adjusted odds ratio, 3.88; 95% confidence interval, 1.09-21.03) and very low birthweight (adjusted odds ratio, 2.22; 95% confidence interval, 1.07-5.73). In contrast, pooled cohort data indicated significantly less preterm birth rates in women with a cerclage: at 34 weeks (relative risk, 0.75; 95% confidence interval, 0.63-0.90), 32 weeks (relative risk, 0.67; 95% confidence interval, 0.49-0.90), and 28 weeks (relative risk, 0.572; 95% confidence interval, 0.39-0.83). Cerclage also reduced risk for infants <1500 g, respiratory distress syndrome, admission at the neonatal intensive care unit, and sepsis. Women with cervical length <15 mm and a cerclage experienced fewer preterm birth rates at <37 weeks (relative risk, 0.88; 95% confidence interval, 0.81-0.94), 34 weeks (relative risk, 0.70; 95% confidence interval, 0.57-0.87), 32 weeks (relative risk, 0.63; 95% confidence interval, 0.50-0.80), and 28 weeks (relative risk, 0.43; 95% confidence interval, 0.32-0.59). Perinatal mortality risk was significant lower in neonates born to mothers with a cerclage. For women with cervical length between 16 and 25 mm, no significant differences in outcomes were observed.

CONCLUSION

Based on our meta-analysis, cerclage may benefit women with a twin pregnancy with an asymptomatic midpregnancy short cervix <25 mm, especially in women with a cervix <15 mm, by reducing preterm birth and improving neonatal outcomes. However, the differences between randomized controlled trials and recent cohort studies emphasize the need for well-powered randomized controlled trials on neonatal outcomes before introducing cerclage in clinical practice for these women.

The impact of maternal serum biomarkers on maternal and neonatal outcomes in twin pregnancies: a retrospective cohort study conducted at a tertiary hospital

Background

Prior prediction models used for screening preeclampsia (PE) in twin pregnancies were found to be inadequate. In singleton pregnancies, various maternal biomarkers have been shown to be correlated with negative pregnancy outcomes. However, the impact of these biomarkers in twin pregnancies remained uncertain.

Methods

A retrospective cohort study was carried out on 736 twin pregnancies at a tertiary hospital in Hangzhou, China. Multivariable logistic models were employed to examine the association between levels of serological markers and the likelihood of adverse pregnancy outcomes. The final logistic model was formulated as a user-friendly nomogram. The primary outcome assessed was the occurrence of PE. Results were presented as odds ratios (ORs) with corresponding 95% confidence intervals (CIs).

Results

The prevalence of PE in the study was 10.3%. When comparing women diagnosed with PE to those without, it was evident that the former group experienced a significantly higher risk of unfavorable maternal and neonatal outcomes. A multivariable logistic regression analysis revealed notable associations between various factors including maternal age, parity, gestational weight gain, a family history of hypertension, as well as levels of cholesterol, albumin, and creatinine and the risk of developing PE, with a significance level of P < 0.05. The concordance index for the constructed nomogram was determined to be 0.792 (95% CI: [0.739-0.844]). Furthermore, an increment of 1 * 1012/L in red blood cell (RBC) count was associated with more than a two-fold increase in the odds of experiencing adverse maternal outcomes (OR 2.247, 95% CI: [1.229-4.107]). However, no significant correlations were identified between any of the examined variables and neonatal outcomes.

Conclusions

In this study, we developed a user-friendly predictive model that achieves notable detection rates by incorporating maternal serum biomarker levels alongside maternal characteristics and medical history. Our findings indicate that the probability of adverse maternal outcomes increases with elevated levels of RBCs. Obstetricians should consider intensifying surveillance for these women in clinical practice.

Study protocol for two randomised controlled trials evaluating the effects of Cerclage in the reduction of extreme preterm birth and perinatal mortality in twin pregnancies with a short cervix or dilatation: the TWIN Cerclage studies

INTRODUCTION

Twin pregnancies have a high risk of extreme preterm birth (PTB) at less than 28 weeks of gestation, which is associated with increased risk of neonatal morbidity and mortality. Currently there is a lack of effective treatments for women with a twin pregnancy and a short cervix or cervical dilatation. A possible effective surgical method to reduce extreme PTB in twin pregnancies with an asymptomatic short cervix or dilatation at midpregnancy is the placement of a vaginal cerclage.

METHODS AND ANALYSIS

We designed two multicentre randomised trials involving eight hospitals in the Netherlands (sites in other countries may be added at a later date). Women older than 16 years with a twin pregnancy at <24 weeks of gestation and an asymptomatic short cervix of ≤25 mm or cervical dilatation will be randomly allocated (1:1) to both trials on vaginal cerclage and standard treatment according to the current Dutch Society of Obstetrics and Gynaecology guideline (no cerclage). Permuted blocks sized 2 and 4 will be used to minimise the risk of disbalance. The primary outcome measure is PTB of <28 weeks. Analyses will be by intention to treat. The first trial is to demonstrate a risk reduction from 25% to 10% in the short cervix group, for which 194 patients need to be recruited. The second trial is to demonstrate a risk reduction from 80% to 35% in the dilatation group and will recruit 44 women. A cost-effectiveness analysis will be performed from a societal perspective.

ETHICS AND DISSEMINATION

This study has been approved by the Research Ethics Committees in the Netherlands on 3/30/2023. Participants will be required to sign an informed consent form. The results will be presented at conferences and published in a peer-reviewed journal. Participants will be informed about the results.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT05968794.

Comparison of singleton and twin birth weight reference percentile curves by gestational age and sex in extremely preterm infants: a population-based study

BACKGROUND

With the increasing survival rate of smaller newborns and twins, previous growth curves may not accurately assess the growth of extremely preterm infants (EPIs). Our study aimed to establish birth weight percentile curves for singletons and twins in EPIs from China and the USA and compare the differences between them.

METHODS

In China, EPIs were from 31 provinces, from 2010 to 2021. The collected information was sex, gestational age, birth weight, singletons and twins. We used the generalised additive models for location scale and shape method to construct the birth weight percentile curves by gestational age and sex for EPIs. The National Vital Statistics System database from 2016 to 2021 was also analysed. We compared the differences between the 50th birth weight percentile curves of the two databases.

RESULTS

We identified 8768 neonates in China (5536 singletons and 3232 twins) and 121 933 neonates in the USA (97 329 singletons and 24 604 twins). We established the 3rd, 10th, 25th, 50th, 75th, 90th and 97th birth weight reference curves for China and the USA. The results showed that males had higher birth weights than females. In China, for the same gestational age and sex, birth weights in singletons and twins were found to be similar, though singleton males born in China had slightly higher birth weights than male twins. In the USA, birth weights were also similar for females and males, with the same gestational age in singletons and twins.

CONCLUSION

We established birth weight reference percentile curves by gestational age and sex for singletons and twins among EPIs in China and the USA.

Comparison of two emergency cervical cerclage techniques in twin pregnancies: A retrospective cohort study matched with cervical dilation

OBJECTIVES

This retrospective cohort study aimed to assess the efficacy of emergency cervical cerclage (ECC) performed with the combined McDonald-Shirodkar technique in twin pregnancies between 18 and 26 weeks of pregnancy with painless cervical dilation 1 to 6 cm.

METHODS

A retrospective cohort study matched with the degree of cervical dilation was conducted. The study group (case group) included women with twin pregnancies undergoing combined McDonald-Shirodkar approach with cervical dilation ≥1 cm between 18 to 26 weeks of gestation at four institutions, from December 2015 to December 2022. To minimize confounding factors, we elucidated the causality structure using a directed acyclic graph and performed 1:1 case-control matching. A control group underwent the McDonald approach. The primary outcome was gestational age (GA) at delivery. The secondary outcomes were pregnancy latency; the rates of spontaneous preterm birth at <28, <30, <32, and <34 weeks; and neonatal outcomes. Additional subanalysis was performed by dividing the patients into two subgroups of women with cervical dilation ≥3 cm and <3 cm.

RESULTS

A total of 84 twin pregnancies were managed with either the combined McDonald-Shirodkar approach (case group: n = 42) or the McDonald approach (control group: n = 42). Demographic characteristics were not significantly different in the two groups (P > 0.05). After adjusting for confounders that were represented by a directed acyclic graph, median GA at delivery was significantly higher (30.5 vs 27 weeks; Bate: 3.40 [95% confidence interval (CI), 2.13-4.67], P < 0.001) and median pregnancy latency was significantly longer (56 vs 28 days; Bate: 24.04 [95% CI, 13.31-34.78], P < 0.001) in the case group compared with the control group. Rates of spontaneous preterm birth at <28, <30, <32, and <34 weeks were significantly lower in the case group than in the control group. For neonatal outcomes, there was higher birth weight (1543.75 vs 980 g; Bate: 420.08 [95% CI, 192.18-647.98], P < 0.001) and significantly lower overall perinatal mortality (7.1% vs 31%; adjusted odds ratio, 0.16 [95% CI, 0.04-0.70], P = 0.014) in the case group compared with the control group. When cervical dilation was ≥3 cm, the combined McDonald-Shirodkar procedure can significantly reduce perinatal mortality (8.3% vs 46.7%; adjusted odds ratio, 0.09 [95% CI, 0.01-0.77], P = 0.028), significantly decrease the risk of delivery at <28 and <30 weeks, and prolong GA at delivery and pregnancy latency compared with the McDonald procedure.

CONCLUSIONS

ECC performed with the combined McDonald-Shirodkar procedure in women with twin pregnancies who have cervical dilation 1 to 6 cm in midtrimester pregnancy may reduce the rate of spontaneous preterm birth and improve perinatal and neonatal outcomes compared with the McDonald procedure, especially for twin pregnancies in women with cervical dilation of 3 to 6 cm and prolapsed membranes.

Transvaginal cerclage for prevention of preterm birth in twin pregnancies with cervical dilatation or shortening: A prospective observational study

OBJECTIVE

To investigate the efficacy of transvaginal cerclage in twin pregnancies with cervical shortening, and to narrow the threshold cervical length for transvaginal cerclage.

METHODS

This is a prospective cohort study and 177 twin pregnancies with asymptomatic cervical dilatation or cervical length of 15 mm or less between 16+0 and 25+6 weeks of pregnancy were included. Patients independently chose either transvaginal cerclage (n = 129) or no cerclage treatment (n = 48) after being consulted on the risk and potential benefit of transvaginal cerclage. The primary outcome measures were gestational age at delivery and neonatal survival rate.

RESULTS

Compared with the no cerclage group, the cerclage group exhibited a higher gestational age at delivery (32.1 ± 4.5 vs 28.3 ± 6.2 weeks, P < 0.001) and a higher neonatal survival rate (86.4% vs 47.9%, P < 0.001). Subgroup analysis showed that in twin pregnancies with cervical dilatation or cervical length less than 10 mm, the cerclage group had significantly higher gestational age at delivery (31.3 ± 4.6 vs 23.4 ± 4.3 weeks, P < 0.001) and a higher neonatal survival rate (123 [85.4%] vs 4 [9.1%], P < 0.001) than the no cerclage group, but in twins when cervical length was 10-15 mm, the two measures were similar between the two groups.

CONCLUSION

Transvaginal cerclage may provide benefits for twins when cervical dilatation or cervical length is less than 10 mm, but its efficacy might not extend to twins when the cervical length is 10-15 mm. Further evidence is needed to confirm the efficacy of transvaginal cerclage for twin pregnancies with a short cervix.

The association of preconceptional folic acid supplementation with gestational age and preterm birth risk in twin pregnancies: a prospective cohort study in China

PURPOSE

This study aims to explore the association of maternal preconceptional folic acid (FA) supplementation with gestational age and preterm birth in twin pregnancies, and whether the association varies by chorionicity or conception mode.

METHODS

From November 2018 to December 2021, the information of FA supplementation and pregnancy outcomes were collected in twin pregnant women. The linear regression models and the logistic regression were used to test the association of preconceptional FA supplementation with gestational age at delivery and preterm birth and premature rupture of membranes (PROM).

RESULTS

A total of 416 twin pregnancies were included. Compared with no use in twins, maternal preconceptional FA use was associated with a 0.385-week longer gestational age (95% CI 0.019-0.751) and lower risk of preterm birth < 36 weeks (adjusted OR 0.519; 95% CI 0.301-0.895) and PROM (adjusted OR 0.426; 95% CI 0.215-0.845). The protective effect on preterm birth < 36 weeks and PROM is similar whether taking FA supplements alone or multivitamins. However, the associations varied by chorionicity and conception mode of twins or compliance with supplementation. The positive associations between preconceptional FA use and gestational age only remained significant among twins via assisted reproductive technology or dichorionic diamniotic twins. Significant protective effects on preterm birth < 36 weeks and PROM were only found among women who took FA at least 4 times a week before conception.

CONCLUSION

Maternal preconceptional FA supplementation was associated with longer gestation duration and lower risk of preterm birth < 36 weeks and PROM in twin pregnancies. To improve the success of their pregnancies, reproductive women should start taking FA supplements well before conception and with good compliance.

Efficacy of emergency cervical cerclage in twin pregnancies and factors affecting the clinical effects of emergency cerclage

OBJECTIVES

To estimate clinical effects of emergency cervical cerclage in twin pregnancies with cervical dilation ≥1.0 cm in mid-trimester of gestation and to identify risk factors after cerclage.

METHODS

This retrospective cohort study included 99 twin pregnancies with cervical dilation ≥1cm in the mid-trimester of gestation at three institutions, from December 2015 through December 2021. The cases were treated with emergency cervical cerclage (52 cases) or expectant management (47 cases). Compare the pregnancy and neonatal outcomes of the two groups. Multiple logistic regression analysis was used to determine the independent risk factors associated with cerclage.

RESULTS

Cerclage placement was associated with significantly longer gestation age and prolongation of the gestational latency (p < .05). In the cases, compared to expectant treatments, spontaneous preterm birth (sPTB) at <26, <28, <30, <32 weeks was significantly less frequent (p < .05). Pre-operation WBC > 11.55 × 10⁹/L, CRP > 10.1 and cervical dilation >3.5 cm were found to be independent risk factors for delivery 28 weeks after cerclage.

CONCLUSIONS

Cervical cerclage in twin pregnancies with cervical dilation ≥1.0 cm in mid-trimester of gestation may prolong pregnancy and gestation age, and improve pregnancy and neonatal outcomes compared with expectant management. The strongest predictor of sPTB before 28 weeks after ECC were pre-operation WBC >11.55 × 10^9/L, CRP > 10.1 and cervical dilation >3.5 cm.

The adverse effect of gestational diabetes mellitus and hypertensive disorders of pregnancy on maternal-perinatal outcomes among singleton and twin pregnancies: a retrospective cohort study (2011-2019)

Background

Gestational diabetes mellitus (GDM) and hypertensive disorders of pregnancy (HDP) are the predominant pregnancy complications among singleton and twin pregnancies worldwide. Our primary objective was to explore the adverse effect of GDM and HDP on maternal-perinatal outcomes compared with non-GDM and non-HDP in singleton and twin pregnancies. The secondary objective was to find the risk of adverse maternal-perinatal outcomes in twin pregnancies compared with singleton pregnancies complicated with GDM and HDP in Hubei, China.

Methods

A tertiary hospital-based retrospective study was conducted at Wuhan University Renmin Hospital, Hubei Province, China, from 2011 to 2019. A chi-square test was used to determine the difference in adverse maternal-perinatal outcomes between singleton and twin pregnancies. A multiple binary logistic regression model and a joinpoint regression model were used to determine the association of GDM and HDP with adverse maternal-perinatal outcomes and GDM and HDP temporal trend among singleton and twin pregnancies.

Results

The trend of HDP [average annual percentage change (AAPC) 15.1% (95% confidence interval (95%CI): 5.3, 25.7)] among singleton pregnancies and GDM [AAPC 50.4% (95%CI: 19.9, 88.7)] among twin pregnancies significantly increased from 2011 to 2019. After adjusting for confounding factors, GDM is associated with an increased risk of C-section (adjusted odds ratio (aOR), 1.5; 95%CI: 1.3, 1.6) and macrosomia (aOR, 1.3; 95%CI: 1.1, 1.6) in singleton and preterm birth (PTB) (aOR, 2.1; 95%CI: 1.2, 3.3) in twin pregnancies compared with non-GDM. HDP was associated with a higher risk of C-section, PTB, perinatal mortality, and low birth weight (LBW) in both singleton and twin pregnancies compared with the non-HDP. Compared with singleton pregnancies complicated with GDM and HDP, twin pregnancies showed higher odds of C-section [(aOR, 1.7; 95%CI: 1.1, 2.7), (aOR, 4.6; 95%CI: 2.5, 8.7), respectively], PTB [(aOR, 22.9; 95%CI: 14.1, 37.3), (aOR, 8.1; 95%CI: 5.3, 12.3), respectively], LBW [(aOR, 12.1; 95%CI: 8.2, 18.1), (aOR, 5.1; 95%CI: 3.6, 7.4), respectively], and low Apgar score [(aOR, 8.2; 95%CI: 4.4, 15.1), (aOR, 3.8; 95%CI: 2.4, 5.8), respectively] complicated with GDM and HDP.

Conclusion

In conclusion, GDM showed an increased risk of a few adverse maternal-perinatal outcomes and HDP is associated with a higher risk of several adverse maternal-perinatal outcomes in singleton and twin pregnancies compared to non-GDM and non-HDP. Moreover, twin pregnancies complicated with GDM and HDP showed higher odds of adverse maternal-neonatal outcomes compared with singleton pregnancies complicated with GDM and HDP.

Antenatal Corticosteroid Treatment During the Late-Preterm Period and Neonatal Outcomes for Twin Pregnancies

Importance

Antenatal corticosteroid treatment of individuals with singletons at risk for delivery during the late-preterm period has been academically recommended. However, the evidence on the use of antenatal corticosteroid treatment for twins at risk for delivery during the late-preterm period is still lacking.

Objective

To evaluate whether antenatal corticosteroid treatment during the late-preterm period in twin pregnancies was associated with a lower risk of newborn morbidity.

Design, Setting, and Participants

This retrospective cohort study of twin pregnancies delivered from February 1, 2013, to September 30, 2020, in a university-affiliated hospital in China included 1974 individuals with twin pregnancies who were at risk for late preterm birth (34 weeks and 0 days to 36 weeks and 6 days of gestation). Data were analyzed from June 30 to July 13, 2023.

Exposures

Antenatal corticosteroid treatment during the late-preterm period.

Main Outcomes and Measures

The primary outcome measure was composite neonatal respiratory morbidity, defined as at least 1 of the following postnatal occurrences in at least 1 neonate of the twins: respiratory distress syndrome, mechanical ventilation, surfactant administration, transferred with respiratory complications, or neonatal death. Propensity score overlap weighting was used to analyze the association between antenatal corticosteroid treatment and the risk of neonatal outcomes.

Results

The study population consisted of 1974 individuals with twin pregnancies, including 303 (15.3%; mean [SD] maternal age, 30.8 [4.2] years) who received antenatal corticosteroid treatment and 1671 (84.7%; mean [SD] maternal age, 31.2 [4.0] years) who did not receive antenatal corticosteroid treatment. The propensity score overlap weighting showed no significant differences between the antenatal corticosteroid treatment group and the no-antenatal corticosteroid treatment group in the risk of neonatal primary outcome (29 of 303 [9.6%] vs 41 of 1671 [2.5%]; weighted odds ratio, 1.27 [95% CI, 0.60-2.76]). None of the subgroup interaction tests were significant for the neonatal primary outcome in terms of gestational age at delivery, year of delivery, chorionicity, at least 1 infant small for gestational age, intertwin growth discordance, and infant sex, and neither was the sensitivity analysis of using propensity score matching and a different administration-to-birth interval and treating twin infants as individuals.

Conclusions and Relevance

This cohort study found insufficient evidence that antenatal corticosteroid treatment during the late-preterm period in twin pregnancies could be associated with a lower risk of newborn morbidity. This new finding can provide a reference for clinical practice.

Differences in prenatal diagnosis rate of congenital anomalies associated with singletons and multiple births: An observational study of more than 1.9 million births in Zhejiang Province, eastern China, during 2012-2018

OBJECTIVE

To characterize differences in the prenatal detection of congenital anomalies (CAs) associated with singleton and multiple births.

METHODS

This observational study covered all births registered in the CA surveillance system in Zhejiang Province of China during 2012-2018. Differences in the incidence and characteristics between singletons and multiple births with CAs were tested. Multivariate logistic regression models were performed to explore the associations of prenatal detection rate of CAs with multiple births.

RESULTS

Totals of 49 872 singletons and 3324 multiple births with CAs were analyzed. The mean incidences of CA for single and multiple births were 27.12 and 54.42 per 1000 births, respectively. After adjustment for covariates, CAs associated with multiple births were less likely to be diagnosed prenatally (adjusted odds ratio [OR] 0.38, 95% confidence interval [CI] 0.34-0.43), as were congenital heart defects, congenital hydrocephalus, cleft lip with cleft palate, cleft lip without cleft palate, limb reduction defects, congenital diaphragmatic hernia, trisomy 21 syndrome, congenital malformation of the urinary system, and other chromosomal malformation, compared with singletons with CAs.

CONCLUSION

Multiple birth is associated with a significantly higher risk of CA, but a significantly lower prenatal diagnosis rate. Therefore, the healthcare of women with multiple pregnancy and their fetuses should be strengthened.

Different subtypes of gestational diabetes mellitus are associated with distinct perinatal outcomes in twin pregnancies

AIMS

To determine whether different gestational diabetes mellitus (GDM) subtypes are associated with distinct perinatal outcomes in twin pregnancies.

MATERIALS

This retrospective cohort study enrolled women with twin pregnancies who gave birth at a tertiary hospital between January 2017 and December 2022. GDM was diagnosed by the IADPSG diagnostic criteria. Three subtypes of GDM were defined as only abnormal fasting glucose (OAFG) values, only abnormal post-load glucose (OAPG) values and abnormal combined fasting and post-load glucose (ACFPG) values. Logistic regression or generalized estimation equation models were used to test the correlation of subtypes of GDM and perinatal outcomes.

RESULTS

GDM with OAPG had a slightly higher risk for preterm delivery (PTD) at <37 gestational weeks (aOR 1.22, 95 %CI 1.01-1.47) and neonatalintensivecareunit (NICU) admission (aOR 1.31, 95 %CI 1.09-1.57). GDM with ACFPG were associated with PTD at <37 gestational weeks (aOR 1.42, 95 %CI 1.06-1.89) and PTD at <34 gestational weeks (aOR 1.65, 95 % CI 1.14-2.39). GDM with OAFG had a lower risk of being small-for-gestational age (SGA) (aOR 0.48, 95 % CI 0.26-0.92).

CONCLUSIONS

Different subtypes of GDM are associated with distinct perinatal outcomes. Only abnormal fasting glucose levels may be responsible for reduced the risk of SGA neonates.

Chorionicity-associated variation in metabolic phenotype of cord blood in twin

BACKGROUND

Monochorionic (MC) twins present a higher incidence of unfavorable clinical perinatal outcomes than dichorionic (DC) twins, often in association with placental vascular anastomosis. In this study, we profiled the umbilical cord plasma metabolomes of uncomplicated MC and DC twin pregnancies and related these to several offspring outcomes, previously associated with birthweight.

METHODS

Umbilical vein blood samples were collected at birth from 25 pairs of uncomplicated MC twins and 24 pairs of uncomplicated DC twins. The samples were subjected to gas chromatography-mass spectrometry-based metabolomics. 152 metabolites were identified from the cord plasma samples of MC and DC twins. Partial least squares discriminant analysis and pathway analysis were performed to compare within DC/MC twin pairs and between DC and MC twins. A generalized estimating equation (GEE) model was utilized to explore the correlation between metabolic differences and birthweight discordance within and between twin pairs.

RESULTS

Our study revealed clear differences between the metabolite profiles of umbilical cord plasma of MC and DC twins. Metabolite profiles in MC within twin pairs and DC within twin pairs were characterized by the differences in 2 - hydroxyglutaramic acid levels and nicotinamide levels, respectively. The metabolic pathways of GSH, tryptophan, and fatty acid metabolism, were significantly downregulated in MC twins compared to DC twins. In addition, the concentration of caffeine and decamethyl-cyclopentasiloxane (D5) was positively correlated with birthweight in MC and DC twins.

CONCLUSION

This study demonstrated that the altered metabolites in umbilical plasma made contributions to the different chorionicities between uncomplicated MC twins and DC twins. The chorionicity of twins seems to affect the metabolic cross-talk between co-twin pairs and be related to birthweight discordance of twins.

Efficacy of ultrasound-indicated cerclage in twin pregnancies: a retrospective case-control study matched by cervical length

BACKGROUND

Twin pregnancies with a progressively shortening cervix in the midterm pregnancy have an increasing risk for spontaneous preterm birth. Currently, there is no known effective method to prevent preterm birth among those women, and the use of an ultrasound-indicated cerclage in twin pregnancies is still controversial.

OBJECTIVE

This study aimed to estimate whether a combination of ultrasound-indicated cerclage, indomethacin, and antibiotics in twin pregnancies between 18 and 26 weeks' gestation could extend the pregnancy, reduce the risk for spontaneous preterm birth, and improve perinatal and neonatal outcomes.

STUDY DESIGN

A retrospective cohort study was conducted. The ultrasound-indicated cerclage group included twin pregnancies with a transvaginal cervical length <25 mm that underwent cerclage at 18 to 26 weeks of gestation in the Women's Hospital, Zhejiang University School of Medicine, from December 2015 through August 2021. Twin pregnancies in our study that underwent cerclage also received antibiotics and indomethacin. A control group of twin pregnancies that were managed expectantly were matched with the treatment group in terms of transvaginal cervical length at diagnosis (±3 mm), gestational age at presentation of diagnosis (±3 weeks), and maternal age (±5 years). An additional subanalysis was performed in which the patients were divided into 2 subgroups based on transvaginal cervical length of either <15 mm or between 15 and 24 mm. The primary outcome was gestational age at delivery. The secondary outcomes were pregnancy latency, the rate of spontaneous preterm birth at <28, <32, <34, <36 weeks' gestation, and neonatal outcomes.

RESULTS

A total of 90 twin pregnancies with a transvaginal cervical length <25 mm were managed with either a cerclage (ultrasound-indicated cerclage group, n=45) or expectantly (control group, n=45). Demographic characteristics were not significantly different between the groups. When compared with the control group, the gestational age at delivery was significantly higher (33.11±3.16 vs 30.22±4.12 weeks; P=.001) and the pregnancy latency was significantly longer (72.40±22.51 vs 45.56±28.82 days; P<.001) in the ultrasound-indicated cerclage group. The rates of spontaneous preterm birth at <28, <32, <34, and <36 weeks' gestation were significantly lower in the ultrasound-indicated cerclage group than in the control group. In terms of neonatal outcomes, there were significant reductions in the overall perinatal mortality (4.4% vs 20.0%; P<.001), neonatal intensive care unit admissions (69.0% vs 92.6%; P<.001), and composite adverse neonatal outcomes (43.7% vs 64.7%; P=.010) for the ultrasound-indicated cerclage group when compared with the control group. In the subgroup of women with a transvaginal cervical length of between 15 and 24 mm (with 21 in the ultrasound-indicated cerclage group vs 21 controls), the data were adjusted for maternal age, pregestational body mass index, in vitro fertilization, operative hysteroscopy, previous cervical surgery, previous spontaneous preterm birth, white blood cell counts, C-reactive protein level, neutrophil to lymphocyte ratio, and the shortest transvaginal cervical length measured at diagnosis. In ultrasound-indicated cerclage group, gestational age at delivery was significantly higher (32.95±3.81 vs 30.24±4.01 weeks; beta, 3.34; 95% confidence interval, 0.14-6.55; P=.042), pregnancy latency was significantly prolonged (77.19±24.81 vs 48.52±29.67 days; beta, 33.81; 95% confidence interval, 12.29-55.34; P=.003), and the rates of spontaneous preterm birth <36 weeks' gestation (57.1% vs 95.2%; adjusted odds ratio, 0.03; 95% confidence interval, 0.01-0.69; P=.029) was significantly decreased, and for neonatal outcomes, there were significant reductions in neonatal intensive care unit admissions (53.7% vs 96.7%; adjusted odds ratio, 0.04; 95% confidence interval, 0.01-0.32; P=.003) and the composite adverse neonatal outcomes (39.0% vs 73.3%; adjusted odds ratio, 0.24; 95% confidence interval, 0.08-0.68; P=.008) in the ultrasound-indicated cerclage group when compared with the control group. In the subgroup of women with a transvaginal cervical length <15 mm, gestational age at delivery was higher (33.25±2.52 vs 30.00±4.33 weeks; beta, 3.96; 95% confidence interval, 1.51-6.42; P=.002), pregnancy latency was significantly prolonged (68.21±19.85 vs 42.96±28.43 days; beta, 30.11; 95% confidence interval, 12.42-47.81; P=.001), rates of spontaneous preterm birth at <32 weeks (16.7% vs 54.2%; adjusted odds ratio, 0.10; 95% confidence interval, 0.01-0.61; P=.020) and <34 weeks (54.2% vs 83.3%, adjusted odds ratio, 0.08; 95% confidence interval, 0.01-0.66; P=.019) of gestation was significantly decreased, and neonatal birthweight was significantly increased (2023.96±510.35 vs 1421.77±611.40 g; beta, 702.40; 95% confidence interval, 297.02-1107.78; P=.001) in the ultrasound-indicated cerclage group when compared with the control group.

CONCLUSION

Cerclage among women with twin pregnancies with a transvaginal cervical length <25 mm may reduce the rate of spontaneous preterm birth and improve perinatal and neonatal outcomes when compared with expectant management. It is worth noting that even with a short transvaginal cervical length of 15 to 24 mm, cerclage will significantly decrease the risk of delivery at <36 weeks' gestation and prolong pregnancy latency. Among women with a short transvaginal cervical length <15 mm, cerclage will significantly decrease the risk of delivery at <32 and <34 weeks' gestation and prolong pregnancy latency.

Clinical analysis on the influencing factors related to preterm twin pregnancy

OBJECTIVE

The aim of this study was to explore the influencing factors of preterm twin pregnancy.

METHODS

In total, 602 twin-pregnant women delivered from February 2016 to February 2020 were analyzed retrospectively. According to whether the pregnant women were preterm or not, they were divided into preterm group (n=363) and term group (n=239). Baseline information, such as maternal age, address, and education level of the pregnant women, were collected. The clinical information of pregnant women, such as chorionic, preeclampsia, gestational diabetes, premature rupture of membranes, abnormal fetal position, and fetal weight, were analyzed. Logistic regression analysis was used to analyze the risk factors. p-value <0.05 was considered statistically significant.

RESULTS

In the preterm group, monochorionic diamniotic comorbidities were significantly higher compared with the control group (p<0.05). Higher risks of preterm group have lower education (p<0.05). Multiple logistic regression analysis demonstrated that education, preeclampsia, and premature rupture of membranes were risk factors for preterm twin pregnancy.

CONCLUSIONS

Preterm birth in twin pregnancy is associated with many risk factors, such as education, preeclampsia, and premature rupture of membranes. Pregnancy supervision and prenatal guidance for twin pregnancy should be strengthened. Furthermore, early detection and diagnosis of comorbidities can improve maternal and neonatal outcomes.

Time trend analysis of perinatal mortality, stillbirth, and early neonatal mortality of multiple pregnancies for each gestational week from the year 2000 to 2019: A population-based study in Japan

Multiple pregnancies pose a high risk of morbidity and mortality in both mothers and infants; thus, obtaining reliable information based on a large population is essential to improve management. We used the maternal and child health statistics, which are published annually, from the database of the Ministry of Health, Labor, and Welfare. The data obtained were aggregated in 5-year intervals, and we used them to analyze the proportion of the number of births for each week of pregnancy to the total of each singleton and multiple pregnancy. For perinatal health indicators (perinatal mortality, stillbirth, and neonatal mortality), the obtained data were calculated and plotted on graphs for each week of pregnancy. Moreover, these indicators were calculated by dividing them into first twin and second twin fetuses. Stillbirth weights were aggregated in several groups, and a histogram was displayed. Between 2000 and 2019, there were 21,068,275 live births, 67,666 stillbirths, and 16,443 early neonatal deaths, excluding 7,148 (7,104 singletons, 44 multiple births) cases, in which the exact gestational weeks at birth were unknown. More than 95% of multiple pregnancies were twin births. Perinatal mortality, stillbirth, and early neonatal mortality rates in multiple pregnancies were the lowest at approximately 37 weeks of gestation and lower than those of single pregnancies at approximately 36 weeks of gestation. Perinatal mortality and stillbirth rates were higher during the delivery of the second twins than the first-born twins, but the early neonatal mortality rate remained approximately the same during the delivery of both twins. As the data in the government database are accumulated and published continuously, indicators can be calculated in the future using the method presented in this study. Further, our findings may be useful for policymaking related to managing multiple pregnancies.

Temporal trends and adverse perinatal outcomes of twin pregnancies at differing gestational ages: an observational study from China between 2012-2020

BACKGROUND

With the development of assisted reproductive technology, the twinning rate in China has been increasing. However, little is known about twinning from 2014 onwards. In addition, previous studies analysing optimal gestational times have rarely considered maternal health conditions. Therefore, whether maternal health conditions affect the optimal gestational time remains unclear.

METHODS

Data of women delivered between January 2012 and December 2020 were collected through China's National Maternal Near Miss Surveillance System. Interrupted time series analysis was used to determine the rates of twinning, stillbirth, smaller than gestational age (SGA), and low Apgar scores (< 4) among twins in China. To estimate the risk of each adverse perinatal outcome for separate gestational weeks, a multivariate generalised linear model was used. Infants born at 37 weeks of gestational age or foetuses staying in utero were used as reference separately. The analyses were adjusted for the sampling distribution of the population and the cluster effect at the hospital and individual levels were considered.

RESULTS

There were 442,268 infants enrolled in this study, and the adjusted rates for twinning, stillbirth, SGA, and low Apgar scores were 3.10%, 1.75%, 7.70%, and 0.79%, respectively. From 2012 to 2020, the twinning rate showed an increasing trend. Adverse perinatal outcomes, including stillbirth, SGA, and low Apgar scores showed a decreasing trend. A gestational age between 34 and 36 weeks decreased most for rate of stillbirth (average changing rate -9.72%, 95% confidence interval [CI] -11.41% to -8.00%); and a gestational age of between 37 and 38 weeks decreased most for rates of SGA (average changing rate -4.64%, 95% CI -5.42% to -3.85%) and low Apgar scores (average changing rate -17.61%, 95% CI -21.73% to -13.26%). No significant difference in changes in twinning rate or changes of each perinatal outcome was observed during periods of different fertility policies. Infants born at 37 weeks of gestation had a decreased risk of stillbirth, SGA, and low Apgar scores. Maternal antepartum or medical complications increased the risk of SGA and low Apgar scores in different gestational weeks.

CONCLUSION

China's twinning rate showed an increasing trend, while adverse perinatal outcomes decreased from 2012 to 2020. Fertility policy changes have had little effect on the twinning rate or the rate of adverse perinatal outcomes such as stillbirth, SGA, or low Apgar scores. The optimal gestational age for twins was 37 weeks. Women pregnant with twins and with antepartum or medical complications should be cautious due to an increased risk of SGA and low Apgar scores.

Impact of maternal gestational weight gain in twin pregnancies on early childhood obesity risk: A longitudinal birth cohort study

OBJECTIVES

To investigate the impact of gestational weight gain (GWG) on the body mass index-for-age z score (BAZ) and obesity risk among twin offspring.

METHODS

This study included 263 women who were pregnant with twins and their offspring. Maternal GWG was measured in each trimester, and infant weight and length were measured at 6, 12, and 24 months.

RESULTS

Total GWG was positively correlated with offspring birthweight and BAZ at 6, 12 and 24 months [adjusted β 0.013 (95% CI: 0.008-0.019), 0.028 (95% CI: 0.005-0.050), 0.033 (95% CI: 0.010-0.056) and 0.025 (95% CI: 0.004-0.047), respectively]. Excessive total GWG was related to an increased relative risk (RR) of large for gestational age (LGA) and overweight at 6 and 12 months. Only the second trimester gestational weight gain rate (GWGR) was positively correlated with birthweight (adjusted β 0.380, 95% CI: 0.256-0.504), and RRs of 6.818 (95% CI: 1.568-29.642) and 2.852 (95% CI: 1.466-5.548) were found for LGA and overweight at 12 months, respectively.

CONCLUSIONS

Total GWG and the second trimester GWGR were correlated with BAZ and overweight/obesity risk in twin offspring; the impact was obvious in the first year of life and gradually disappeared over time.

CLINICAL TRIAL REGISTRATION

ChiCTR-OOC-16008203, Registered on 1 April 2016 at the Chinese Clinical Trial Registry.

Incidence and Risk Factors of Postpartum Hemorrhage in China: A Multicenter Retrospective Study

Background: Postpartum hemorrhage (PPH) is a leading cause of maternal morbidity and mortality worldwide but the incidence and its risk factors in China is limited. The objective of this study is to investigate the incidence and the risk factors of PPH in Chinese women.

Methods: A multi-center retrospective study of pregnant women at ≥28 weeks of gestation was conducted. Logistic regression was used to identify potential risk factors of PPH and receiver operating characteristic curve was used to evaluate the predictive performance of the identified risk factors. Subgroup analysis focusing on the number of fetus and the mode of delivery was conducted.

Results: A total of 99,253 pregnant women were enrolled and 804 (0.81%) experienced PPH. The subgroup analysis revealed that the incidence of PPH was 0.75, 2.65, 1.40, and 0.31% in singletons, twin pregnancies, cesarean sections, and vaginal deliveries, respectively. Placenta previa and placenta accreta were the predominant risk factors of PPH in the overall population and all subgroups. A twin pregnancy was a risk factor for PPH regardless of the mode of delivery. Obesity, and multiparity were risk factors for PPH in both singletons and cesarean section cases, but the latter predicted a reduced probability of PPH in vaginal deliveries. Macrosomia was associated with increased risk of PPH in singletons or vaginal deliveries. In women who delivered vaginally, preeclampsia was associated with a higher risk of PPH. The areas under the curve for the overall cohort, singletons, twin pregnancies, cesarean section cases, and vaginal deliveries were 0.832 (95% confidence interval [CI] 0.813–0.851), 0.824 (95% CI 0.803–0.845), 0.686 (95% CI 0.617–0.755), 0.854 (95% CI 0.834–0.874), and 0.690 (95% CI 0.646–0.735), respectively.

Conclusions: The risk factors of PPH varied slightly based on the number of fetuses and the mode of delivery, while placenta previa and placenta accreta were the two major risk factors. A combination of the identified risk factors yielded a satisfactory predictive performance in determining PPH in the overall cohort, singletons pregnancies, and women who delivered by cesarean section, whereas the performance was moderate in twin pregnancies and in women delivering vaginally.

Association between maternal exposure to gaseous pollutants and atrial septal defect in China: A nationwide population-based study

BACKGROUND

The association between maternal exposure to gaseous air pollutants and congenital heart defects (CHD) remains unclear. The concentration-response relationship and the time windows of susceptibility to gaseous pollutants may vary by pollutant species and CHD subtypes.

OBJECTIVE

We aimed to examine the relationship between maternal exposures to four species of gaseous pollutants (NO₂, O₃, SO₂, and CO) and atrial septal defect (ASD), which is a common subtype of CHD, and to determine the critical time windows of susceptibility for each gaseous pollutant.

METHODS

Among 1,253,633 infants born between October 1, 2013 and December 31, 2016 in China, 1937 newborns were diagnosed with isolated ASD, a prevalence of 1.55‰. Maternal exposures to the gaseous pollutants were estimated by matching the geocoded maternal addresses with the gridded ambient concentrations. The adjusted odds ratios (aOR) between exposures and ASD were quantified by using mixed-effects logistic regression models.

RESULTS

We found significantly positive associations between ASD and maternal exposures to NO₂, O₃, SO₂, and CO during entire pregnancy, first-, second-, and third-trimester. However, no statistically significant association was found between maternal exposure to PM_2.5, PM_2.5-10 and ASD risk (P > 0.05). In the fully adjusted model with respect to average exposure over entire pregnancy, the adjusted odds ratios (aOR) for each 10 μg/m³ increment of NO₂, O₃, SO₂ were 1.33 (95% CI: 1.22-1.45), 1.13 (95% CI: 1.10-1.16), 1.28 (95% CI: 1.20-1.35), respectively; the aOR for each 100 μg/m³ increment of CO was 1.10 (95% CI: 1.06-1.15). The observed concentration-response relationships varied by exposure periods and pollutants, with the strongest association for NO₂ during the 1st-8th embryology weeks, for O₃ during the third trimester, for SO₂ during the second trimester, and for CO without obvious variation.

CONCLUSIONS

The findings suggest an increased risk of ASD in association with maternal exposures to four common gaseous pollutants. From the perspective of birth defects prevention and ASD risk mitigation, it is critical to reduce maternal exposure to gaseous pollutants especially during the most susceptible time windows.

Association of infant feeding patterns with body fat mass and obesity in the first 2 years of life: a longitudinal twin birth cohort study

Childhood obesity is a major public health problem with no effective intervention. We explored the influence of feeding patterns on infants' growth indices within the first 2 years in a twin birth cohort. Dietary intake at 12 months was recorded with a food frequency questionnaire, and dietary patterns were identified by principal component analysis. Milk feeding methods in first 6 months were categorised as breastfeeding or exclusive formula feeding. Correlations between feeding patterns and infants' growth indices were examined via generalised estimating equations. Two dietary patterns were identified and neither of which was related to growth indices. Breastfed infants had a higher body fat mass (BFM) percentage at 12 months, a higher body mass index (BMI) increment from birth to 6 months and a lower BMI increment from 6 to 12 months. Breastfed infants were likely positively correlated with BFM at 12 months; as complementary food was added, the effect of breastfeeding on growth gradually decreased.

Is Adherence to the Provisional Institute of Medicine Guidelines of Weight Gain Associated With Better Perinatal Outcomes? A Retrospective Cohort Study of Twin Pregnancies in Southwest China

The applicability of the Institute of Medicine (IOM) recommendations of gestational weight gain (GWG) for Chinese twin gestations is uncertain. In this article, we aimed to investigate the associations between GWG among twin gestations, as categorized according to the 2009 IOM guidelines and perinatal outcomes in Chengdu, China. A retrospective cohort study of pregnant women delivering live twins ≥28 weeks at a tertiary maternal and child hospital was conducted. The incidences of perinatal outcomes were compared across 3 groups-that is, women with low, adequate, and excessive GWG. Logistic regression analyses were next performed to confirm the associations while taking into account potential confounders. Results showed that low GWG was associated with a higher risk of preterm birth, low and very low birthweight, neonatal intensive care unit admission, and gestational diabetes, whereas preeclampsia was more frequent among excessive GWG women. In conclusion, adherence to the 2009 IOM guidelines for twin pregnancies are associated with improved perinatal outcomes. This has the potential to improve short- and long-term public health outcomes.

Geographic variations in the incidence of congenital hypothyroidism in China: a retrospective study based on 92 million newborns screened in 2013-2018

BACKGROUND

Although congenital hypothyroidism (CH) has been widely studied in Western countries, CH incidence at different administrative levels in China during the past decade remains unknown. This study aimed to update the incidence and revealed the spatial pattern of CH incidence in the mainland of China, which could be helpful in the planning and implementation of preventative measures.

METHODS

The data used in our study were derived from 245 newborns screening centers that cover 30 provinces of the Chinese Newborn Screening Information System. Spatial auto-correlation was analyzed by Global Moran I and Getis-Ord Gi statistics at the provincial level. Kriging interpolation methods were applied to estimate a further detailed spatial distribution of CH incidence at city level throughout the mainland of China, and Kulldorff space scanning statistical methods were used to identify the spatial clusters of CH cases at the city level.

RESULTS

A total of 91,921,334 neonates were screened from 2013 to 2018 and 42,861 cases of primary CH were identified, yielding an incidence of 4.66 per 10,000 newborns screened (95% confidence interval [CI]: 4.62-4.71). Neonates in central (risk ratio [RR] = 0.84, 95% CI: 0.82-0.85) and western districts (RR = 0.71, 95% CI: 0.69-0.73) had lower probability of CH cases compared with the eastern region. The CH incidence indicated a moderate positive global spatial autocorrelation (Global Moran I value = 0.394, P  < 0.05), and the CH cases were significantly clustered in spatial distribution. A most likely city-cluster (log-likelihood ratio [LLR] = 588.82, RR = 2.36, P  < 0.01) and 25 secondary city-clusters of high incidence were scanned. The incidence of each province and each city in the mainland of China was estimated by kriging interpolation, revealing the most affected province and city to be Zhejiang Province and Hangzhou city, respectively.

CONCLUSION

This study offers an insight into the space clustering of CH incidence at provincial and city scales. Future work on environmental factors need to focus on the effects of CH occurrence.

Changes in Multiple Birth Rates and Parental Demographic Factors in South Korea During the Last Four Decades: 1981-2019

Over the previous decades, twinning rates worldwide have increased remarkably. This study aimed to describe changes in multiple birth rates and related demographic characteristics, such as maternal age and the level of education of parents in South Korea from 1981 to 2019. This study analyzed birth data obtained from the Korean Statistical Information Service. From 1981 to 2019, the total twinning rate increased from 5 to 22.5 pairs per 1000 births. This rapid increase was due to an increase in dizygotic twin births, which mainly occurred in mothers aged between 30 and 39 years. The average maternal age of multiples increased from 26.06 years in 1981 to 33.98 years in 2019, suggesting that a delay in childbearing contributed to the increase in the twinning rate. The percentage of mothers of multiples who completed a college or higher degree (CHD) increased by 1000% from 1981 to 2019, indicating that a sharp increase in the level of education of females in part explains the delay in childbearing. The percentages of individuals who completed a CHD were higher among parents of multiples than among those of singletons in recent years when public funding arrangements for fertility treatments were available. This result suggested that completion of higher education may be associated with increased use of assisted reproductive technology (ART) independent of the financial status of couples. Taken together, the analysis suggested that increased maternal age, ART and the increased number of females who completed CHD may be responsible for the remarkable increase in the rates of multiple births in South Korea in the last four decades.

Should singleton birth weight standards be applied to identify small-for-gestational age twins?: analysis of a retrospective cohort study

BACKGROUND

Twin birth weight percentiles are less popular in clinical management among twin pregnancies compared with singleton ones in China. This study aimed to compare the incidence and neonatal outcomes of small for gestational age (SGA) twins between the use of singleton and twin birth weight percentiles.

METHODS

This was a retrospective cohort study of 3,027 pregnancies with liveborn twin pairs at gestational age of > 28 weeks. The newborns were categorized as SGA when a birthweight was less than the 10th percentile based on the singleton and twin references derived from Chinese population. Logistic regression models with generalized estimated equation (GEE) were utilized to evaluate the association between SGA twins and neonatal outcomes including neonatal unit admission, neonatal jaundice, neonatal respiratory distress (NRDS), neonatal asphyxia, ventilator support, hypoxic ischemic encephalopathy (HIE), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), intracranial hemorrhage (ICH), culture-proven sepsis, neonatal death within 28 days after birth as well as the composite outcome.

RESULTS

The incidence of SGA was 33.1 % based on the singleton reference and 7.3 % based on the twin reference. Both of SGA newborns defined by the singleton and twin references were associated with increases in neonatal unit admission, neonatal jaundice and ventilator support. In addition, SGA newborns defined by the twin reference were associated with increased rates of BPD (aOR, 2.61; 95 % CI: 1.18-5.78) as well as the severe composite outcome (aOR, 1.93; 95 % CI: 1.07-3.47).

CONCLUSIONS

The use of singleton birth weight percentiles may result in misdiagnosed SGA newborns in twin gestations and the twin birth weight percentiles would be more useful to identify those who are at risk of adverse outcomes.

Pregnancy outcomes and factors affecting the clinical effects of emergency cerclage in twin pregnancies with cervical dilation and prolapsed membranes

OBJECTIVE

To determine the effect of mid-trimester emergency cerclage in women with twin pregnancies with cervical dilation and prolapsed membranes, and to identify risk factors predicting spontaneous preterm birth (sPTB) before 28 weeks, after cerclage.

METHODS

Retrospective analysis of twin gestations with cervical dilation and prolapsed membranes treated with emergency cerclage or expectant management (2015-2020). The primary outcomes were the rate of sPTB before 28 weeks and the gestational latency. Multiple logistic regression analysis was used to determine the factors associated with sPTB before 28 weeks, after cerclage.

RESULTS

Ninety-seven women were included, cerclage (n = 58) or no cerclage (n = 39). Cerclage placement was associated with significantly lower incidence of sPTB before 28 weeks of pregnancy (34.5% vs 82.1%) and prolongation of the gestational latency (46.71 ± 27.52 vs 10.95 ± 11.71 days). Positive cervical culture (odds ratio [OR] 10.69, 95% confidence interval [CI] 1.82-62.95), pregnancy duration at diagnosis less than 22 weeks (OR 9.42; 95% CI 1.69-52.69) and cervical dilation at least 4 cm (OR 7.92; 95% CI 1.40-44.71) were found to be independent risk factors for sPTB before 28 weeks, after cerclage.

CONCLUSION

Emergency cerclage in women with twin pregnancies with cervical dilation and prolapsed membranes was associated with an overall 40% decrease in sPTB before 28 weeks and a prolongation of latency by 5 weeks. The strongest predictor of sPTB before 28 weeks after cerclage was a positive cervical culture.

Twin Peaks: more twinning in humans than ever before

STUDY QUESTION

How many twins are born in human populations and how has this changed over recent decades?

SUMMARY ANSWER

Since the 1980s, the global twinning rate has increased by a third, from 9.1 to 12.0 twin deliveries per 1000 deliveries, to about 1.6 million twin pairs each year.

WHAT IS KNOWN ALREADY

It was already known that in the 1980s natural twinning rates were low in (East) Asia and South America, at an intermediate level in Europe and North America, and high in many African countries. It was also known that in recent decades, twinning rates have been increasing in the wealthier parts of our world as a result of the rise in medically assisted reproduction (MAR) and delayed childbearing.

STUDY DESIGN, SIZE, DURATION

We have brought together all information on national twinning rates available from statistical offices, demographic research institutes, individual survey data and the medical literature for the 1980-1985 and the 2010-2015 periods.

PARTICIPANTS/MATERIALS, SETTING, METHODS

For 165 countries, covering over 99% of the global population, we were able to collect or estimate twinning rates for the 2010-2015 period. For 112 countries, we were also able to obtain twinning rates for 1980-1985.

MAIN RESULTS AND THE ROLE OF CHANCE

Substantial increases in twinning rates were observed in many countries in Europe, North America and Asia. For 74 out of 112 countries the increase was more than 10%. Africa is still the continent with highest twinning rates, but Europe, North America and Oceania are catching up rapidly. Asia and Africa are currently home to 80% of all twin deliveries in the world.

LIMITATIONS, REASONS FOR CAUTION

For some countries, data were derived from reports and papers based on hospital registrations which are less representative for the country as a whole than data based on public administrations and national surveys.

WIDER IMPLICATIONS OF THE FINDINGS

The absolute and relative number of twins for the world as a whole is peaking at an unprecedented level. An important reason for this is the tremendous increase in medically assisted reproduction in recent decades. This is highly relevant, as twin deliveries are associated with higher infant and child mortality rates and increased complications for mother and child during pregnancy and during and after delivery.

STUDY FUNDING/COMPETING INTEREST(S)

The contribution of CM was partially supported by the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant No 681546, FAMSIZEMATTERS), Nuffield College, and the Leverhulme Trust. The contribution of GP was partially supported by the French Agence Nationale de la Recherche (grant No ANR-18-CE36-0007-07). The authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Perinatal Outcomes and Risk Factors for Preterm Birth in Twin Pregnancies in a Chinese Population: A Multi-center Retrospective Study

Background: Twin pregnancies are associated with an increased risk of adverse maternal and neonatal outcomes, mainly owing to prematurity. Few studies have evaluated the risk factors for preterm birth (PTB) in Chinese population. The objective of this study is to present the short-term maternal-neonatal outcomes, investigating the potential risk factors associated with preterm birth in Chinese twin pregnancies.

Methods: A multi-center retrospective study of women pregnant with twins ≥28 weeks of gestation was conducted. Maternal and neonatal outcomes were analyzed. Logistic regression was used to identify potential risk factors for PTB before 37, 34, and 32 weeks, respectively.

Results: A total of 3,288 twin pregnancies and 6,576 neonates were included in 99,585 pregnancies. The rate of twin pregnancy was 3.3%, while the PTB rate before 37, 34, and 32 weeks among this population were 62.1, 18.8, and 10.4%, respectively. Logistic regression revealed that monochorionicity [Odds ratio (OR) 3.028, 95% confident interval (CI) 2.489–3.683, P < 0.001], gestational weight gain (GWG) <10 kg (OR 2.285, 95% CI 1.563–3.339, P < 0.001) and GWG between 10 and 15 kg (OR 1.478, 95% CI 1.188–1.839, P < 0.001), preeclampsia (PE) (OR 3.067, 95% CI 2.142–4.390, P < 0.001), and intrahepatic cholestasis of pregnancy (ICP) (OR 3.122, 95% CI 2.121–4.596, P < 0.001) were the risk factors for PTB before 37 weeks. Monochorionicity (OR 2.865, 95% CI 2.344–3.501, P < 0.001), age < 25 years (OR 1.888, 95% CI 1.307–2.728, P = 0.001), and GWG <10 kg (OR 3.100, 95% CI 2.198–4.372, P < 0.001) were risk factors for PTB before 34 weeks. Monochorionicity (OR 2.566, 95% CI 1.991–3.307, P < 0.001), age younger than 25 years (OR 1.964, 95% CI 1.265–3.048, P = 0.003), and GWG <10 kg (OR 4.319, 95% CI 2.931–6.364, P < 0.001) were the risk factors for PTB before 32 weeks.

Conclusions: Monochorionicity and GWG <10 kg were two major risk factors for PTB before 32, 34, and 37 weeks, whereas maternal age, PE, and ICP were also risk factors for PTB in specific gestational age.

Conjoined twins in a spontaneous monochorionic triplet pregnancy: A case report and literature review

RATIONALE

Conjoined twins are a rare complication of monochorionic pregnancies and an extremely rare condition in spontaneous triplet pregnancies. We report a case of conjoined twins in a spontaneous monochorionic triplet pregnancy. The conjoined twins might have suffered from twin anemia-polycythemia sequence, which was reported to be extremely rare.

PATIENT CONCERNS

A 26-year-old woman conceived spontaneously with an obstetric history of invasive mole 4 years ago.

DIAGNOSES

We initially misdiagnosed her as having monochorionic triamniotic triplets at 10 weeks of gestation. However, we confirmed conjoint twins with the monochorionic diamniotic triplet pregnancy at 12 weeks of gestation and classified them as omphalopagus.

INTERVENTIONS

As the woman decided to continue the pregnancy, regular and careful antenatal care was conducted.

OUTCOMES

Unexpectedly, she had a stillbirth 3 weeks later and had to terminate the pregnancy at 15 weeks of gestation. After abortion, the diagnosis of omphalopagus was confirmed in the induced fetuses. Moreover, the skin colors of the conjoined twins were different: one was plethoric, and the other was pale. Additionally, the parents agreed to examine the chromosome of the fetuses, and the results were normal.

CONCLUSION

Dichorionic triplet and monochorionic triplet pregnancies have a poorer prognosis than trichorionic triplet pregnancies. Surgery is the main therapy for conjoined twins; however, most conjoined twins in triplet pregnancies cannot survive, including omphalopagus twins. The conjoined twins may have suffered from twin anemia-polycythemia sequence, which could probably not be diagnosed intrauterine. Transvaginal probe and 3-dimensional ultrasound may be helpful for clarifying the diagnosis in early pregnancy.

Ten-year time trends in preterm birth during a sociodemographic transition period: a retrospective cohort study in Shenzhen, China

OBJECTIVES

To investigate time trends of preterm birth and estimate the contributions of risk factors to the changes in preterm birth rates over a decade (2009-2018) of transitional period in Shenzhen, China.

DESIGN

Retrospective cohort study between 2009 and 2018.

SETTING

All births in Baoan during January 2009 and December 2018 registered in the Shenzhen Birth Registry Database.

PARTICIPANTS

478 044 live births were included with sociodemographic and medical records for both women and infants.

OUTCOME MEASURES

The incidence rate of preterm birth stratified by different maternal and infant characteristics. Multiple logistic regression was used to identify significant risk factors associated with preterm birth. The population attributable risk fraction of each factor was calculated to estimate its contribution to variations of preterm birth rate over the 10 years.

RESULTS

A total of 27 829 preterm births from 478 044 (5.8%) live births were recorded and the preterm birth rate increased from 5.5% in 2009 to 6.2% in 2018. Medically induced preterm birth rate increased from 2.0% in 2009 to 3.4% in 2018 while spontaneous preterm labour rate decreased from 3.3% to 2.7% over the decade years. Risk factors including multiple pregnancy (0.28% increase) drove the rise of preterm birth rate, whereas changes in maternal educational attainment (0.22% reduction) and prenatal care utilisation (0.45% reduction) had contributed to the decline in preterm birth rate.

CONCLUSIONS

An uptrend of preterm birth rate was observed in an area under rapid sociodemographic transitions during 2009-2018 and the changes were associated with these sociodemographic transitions. Continued investments in girls' education and prenatal care have the potential of reducing preterm birth rate.

The Chinese National Twin Registry: a 'gold mine' for scientific research

The Chinese National Twin Registry (CNTR) currently includes data from 61 566 twin pair from 11 provinces or cities in China. Of these, 31 705, 15 060 and 13 531 pairs are monozygotic, same-sex dizygotic and opposite-sex dizygotic pairs, respectively, determined by opposite sex or intrapair similarity. Since its establishment in 2001, the CNTR has provided an important resource for analysing genetic and environmental influences on chronic diseases especially cardiovascular diseases. Recently, the CNTR has focused on collecting biologic specimens from disease-concordant or disease-discordant twin pairs or from twin pairs reared apart. More than 8000 pairs of these twins have been registered, and blood samples have been collected from more than 1500 pairs. In this review, we summarize the main findings from univariate and multivariate genetic effects analyses, gene-environment interaction studies, omics studies exploring DNA methylation and metabolomic markers associated with phenotypes. There remains further scope for CNTR research and data mining. The plan for future development of the CNTR is described. The CNTR welcomes worldwide collaboration.