Yi Mu

Birth weight reference percentiles for Chinese.

Objective To develop a reference of population-based gestational age-specific birth weight percentiles for contemporary Chinese. Methods Birth weight data was collected by the China National Population-based Birth Defects Surveillance System. A total of 1,105,214 live singleton births aged ≥28 weeks of gestation without birth defects during 2006–2010 were included. The lambda-mu-sigma method was utilized to generate percentiles and curves. Results Gestational age-specific birth weight percentiles for male and female infants were constructed separately. Significant differences were observed between the current reference and other references developed for Chinese or non-Chinese infants. Conclusion There have been moderate increases in birth weight percentiles for Chinese infants of both sexes and most gestational ages since 1980s, suggesting the importance of utilizing an updated national reference for both clinical and research purposes.

Recent trends in the birth prevalence of Down syndrome in China: impact of prenatal diagnosis and subsequent terminations

This study aims to analyze recent trends in Down syndrome (DS) prevalence in China and evaluate the impact of prenatal diagnosis and subsequent terminations.

Sociodemographic and obstetric characteristics of stillbirths in China: a census of nearly 4 million health facility births between 2012 and 2014

BACKGROUND Very little is known about the burden and determinants of stillbirths in China. We used data from a national surveillance system for health facility births to compute a stillbirth rate representative of all facility births in China and to explore sociodemographic and obstetric factors associated with variation in the stillbirth rate. METHODS We used data from Chinas National Maternal Near Miss Surveillance System between Jan 1, 2012, and Dec 31, 2014, which covers 441 hospitals in 326 urban districts and rural counties. The surveillance aimed to enumerate all maternal deaths and near misses in health facilities, and collected data prospectively for all pregnant or post-partum women admitted to the obstetric department. We restricted the analysis to births of 28 or more completed weeks of gestation or 1000 g or heavier birthweight. We examined the strength of association between sociodemographic characteristics, gestational age, and obstetric complications and stillbirths using logistic regression, taking account of the sampling strategy and clustering of births within hospitals and in cases of more than one birth per woman. FINDINGS There were 3 956 836 births and 37 855 stillbirths, giving a stillbirth rate of 8·8 per 1000 births (95% CI 8·8-8·9). The stillbirth rate was particularly high for women younger than 15 years of age (59·9 stillbirths per 1000 births), those who had not sought antenatal care (38·3 per 1000), the unmarried (32·5 per 1000), those with no education (26·9 per 1000), or those who had had four or more births (23·2 per 1000). A high proportion (29 319 [78·2%] of 37 514) of stillbirths occurred at gestational ages of younger than 37 weeks, and about two thirds (24 787 [66·1%] of 37 514) were in women without any maternal complication at the time of birth. Of babies born at normal gestations (37-41 weeks), maternal complications substantially increased the risk of stillbirth (odds ratio comparing antepartum or intrapartum complications with no complication 3·96 [95% CI 3·66-4·29]), but only a small proportion (1638 [4·4%] of 37 514) of stillbirths fell into this group. INTERPRETATION Our analysis of nearly 4 million births in 441 health facilities in China suggests a stillbirth rate of 8·8 per 1000 births between 2012 and 2014. Stillbirths do not feature in the Chinese Governments 5 year plans and most information systems do not include stillbirths. The Government need to start paying attention to stillbirths and invest strategically in antenatal care, particularly for the most disadvantaged women, including the very young, unmarried, and illiterate, and those at high parity. FUNDING National Health and Family Planning Commission of the Peoples Republic of China, National Natural Science Foundation of China, China Medical Board, WHO, and UNICEF.

Relaxation of the one child policy and trends in caesarean section rates and birth outcomes in China between 2012 and 2016: observational study of nearly seven million health facility births

Abstract Objective To examine how the relaxation of the one child policy and policies to reduce caesarean section rates might have affected trends over time in caesarean section rates and perinatal and pregnancy related mortality in China. Design Observational study. Setting China’s National Maternal Near Miss Surveillance System (NMNMSS). Participants 6 838 582 births at 28 completed weeks or more of gestation or birth weight ≥1000 g in 438 hospitals in the NMNMSS between 2012 and 2016. Main outcome measures Obstetric risk was defined using a modified Robson classification. The main outcome measures were changes in parity and age distributions and relative frequency of each Robson group, crude and adjusted trends over time in caesarean section rates within each risk category (using Poisson regression with a robust variance estimator), and trends in perinatal and pregnancy related mortality over time. Results Caesarean section rates declined steadily between 2012 and 2016 (crude relative risk 0.91, 95% confidence interval 0.89 to 0.93), reaching an overall hospital based rate of 41.1% in 2016. The relaxation of the one child policy was associated with an increase in the proportion of multiparous births (from 34.1% in 2012 to 46.7% in 2016), and births in women with a uterine scar nearly doubled (from 9.8% to 17.7% of all births). Taking account of these changes, the decline in caesarean sections was amplified over time (adjusted relative risk 0.82, 95% confidence interval 0.81 to 0.84). Caesarean sections declined noticeably in nulliparous women (0.75, 0.73 to 0.77) but also declined in multiparous women without a uterine scar (0.65, 0.62 to 0.77). The decrease in caesarean section rates was most pronounced in hospitals with the highest rates in 2012, consistent with the government’s policy of targeting hospitals with the highest rates. Perinatal mortality declined from 10.1 to 7.2 per 1000 births over the same period (0.87, 0.83 to 0.91), and there was no change in pregnancy related mortality over time. Conclusions China is the only country that has succeeded in reverting the rising trends in caesarean sections. China’s success is remarkable given that the changes in obstetric risk associated with the relaxation of the one child policy would have led to an increase in the need for caesarean sections. China’s experience suggests that change is possible when strategies are comprehensive and deal with the system level factors that underpin overuse as well as the various incentives at work during a clinical encounter.

The Sex Ratio at Birth for 5,338,853 Deliveries in China from 2012 to 2015: A Facility-Based Study

Objective The accuracy of a population-based sex ratio at birth (SRB) in China has long been questioned. To depict a more accurate profile, the present study used data from a national surveillance system for health facility births to explore the characteristics of SRB in China. Methods Data from China’s National Maternal Near Miss Surveillance System between 2012 and 2015 were used. We restricted the analysis to live births of ≥28 completed gestational weeks or ≥1000 g birth weight. The strength of association between obstetric characteristics and SRB was examined using logistic regression, taking into account the sampling strategy and clustering of births within health facilities. Results There were 2,785,513 boys and 2,549,269 girls born alive between 2012 and 2015 in 441 health facilities. The SRB was 111.04 in 2012, 110.16 in 2013, 108.79 in 2014, and 109.53 in 2015. The SRB was high in the eastern region, especially in rural areas. The SRBs increased with mother’s age and decreased with mother’s education. The SRB in women who were pregnant for the first time was 104.30. The SRB in primipara was normal (104.35), but it was extremely high in non-primipara, especially for women with three or more parities (141.76); only 5.26% of live births fell within this group. The SRBs increased significantly by the number of parities, especially in the rural areas of the central region. After adjustment for sociodemographic factors, women with three or more parities were 1.39 (95% CI 1.34, 1.43) times more likely to give birth to a boy compared with primiparae who were pregnant for the first time. Conclusion Our analysis suggests that the SRB was lower than what was reported officially but higher than normal. The government should keep strengthening supervision to prevent sex-selection, especially in the wake of the two-child policy implemented in 2015.

Low birthweight in China: evidence from 441 health facilities between 2012 and 2014

Abstract Objective: This study aimed to identify new evidence about the burden and risk factors of low birthweight (LBW) in China using national facility-based data. Methods: The association between sociodemographic and obstetric characteristics and LBW was examined using a multilevel model, taking into account the clustering of livebirths within hospitals and multiple gestations per woman. Results: There were 3 915 965 deliveries and 235 247 cases born with LBW, producing a LBW rate of 5.36% in mainland China; 65.34% of all cases of LBW were caused by preterm birth. The LBW rate was particularly high for women who delivered at home, were younger than 14 years of age, were unmarried, were illiterate, had not received antenatal care, had delivered three or more infants and who had multiple gestations. Maternal complications were strongly associated with LBW, but the risk effects of full-term LBW were lower than for of LBW. Conclusions: China’s LBW rate was lower than that of many other countries, but due to its large population size, the number of infants born with LBW still contributed significantly to the overall number of LBW births globally. By recognizing populations of the most disadvantaged women, we can identify opportunities for prevention and intervention that target LBW.

Population-based birth weight reference percentiles for Chinese twins

Abstract Background: Birth weight percentiles by gestational age are important for assessing prenatal growth and predicting postnatal outcomes of newborns. Several countries have developed nation-specific birth weight references for twins, but China still lacks such references. Methods and results: Birth weight data for twins born between October 2006 and September 2015 were abstracted from the China National Population-based Birth Defects Surveillance System. A total of 54,786 live twin births aged ≥28 weeks of gestation without birth defects were included in the analysis. The LMS method was adopted to generate gestational age-specific birth weight percentiles and curves for male and female twins separately. Significant differences were observed between the current reference and other references developed for Chinese or non-Chinese twins. The neonatal mortality rate in this cohort was 12.3‰, and much higher rates at very early gestation weeks were identified in small-for-gestational-age twins grouped by the newly developed reference cutoffs. Conclusions: The established birth weight centiles represent the first birth weight norm for contemporary Chinese twins and can be a useful tool to assess growth of twins in clinical and research settings. Key Messages There have been no population-based birth weight percentiles for Chinese twins prior to this study. The established birth weight centiles for female and male twins are markedly lower than those for Chinese singletons. Twin-specific curves should be used for determining inappropriate for gestational age in twins rather than using existing singleton reference. The birth weight percentiles for twins differed significantly from those for non-Chinese twins. In addition to ethnic influences, the observed differences could be ascribed to variations in prenatal care, fetal or maternal nutrition status or other environmental factors. Neonatal mortality rates varied considerably among twins grouped by the newly developed reference percentiles. Small-for-gestational-age twins had much higher mortality than did appropriate-for-gestational-age twins, highlighting the need to reduce postnatal mortality by improving perinatal health care for twins.

Assessment of interaction between maternal polycyclic aromatic hydrocarbons exposure and genetic polymorphisms on the risk of congenital heart diseases

The major causes of congenital heart diseases (CHDs) are the interactions of genetic and environmental factors. We conducted a case–control study in 357 mothers of CHDs fetuses and 270 control mothers to investigate the association of maternal PAHs exposure, AHR, CYP1A1, CYP1A2, CYP1B1 and CYP2E polymorphisms, the interaction between PAHs exposure and genetic variants with the risk of CHDs. The higher level PAHs exposure was associated with the risk of CHDs (aOR = 2.029, 95% CI: 1.266, 3.251) or subtypes. The haplotypes of AHR or CYP1A2 were associated with the risk of CHDs: AHR: C-G-A-C: aOR = 0.765; T-A-G-A: aOR = 1.33; CYP1A2: A-T:aOR = 1.75; C-C: aOR = 0.706. When exposed to higher level PAHs, the risk of CHDs among the mothers carrying rs2158041 “C/T or T/T” genotype or rs7811989 “G/A or A/A” genotype in AHR was 1.724 (χ2 = 7.209, P = 0.007) or 1.735 (χ2 = 7.364, P = 0.007) times greater than the aOR in the mothers carrying wild genotype. The multiplicative-scale interactions between PAHs exposure and polymorphisms of CYP1A2 rs4646425 (P = 0.03) or CYP2E1 rs915908 (P = 0.0238) on the risk of CHDs were observed. Our study suggests that maternal AHR polymorphisms may modify the association of PAHs exposure with CHDs, CYP1A2 or CYP2E1 polymorphisms significantly interact with PAHs exposure on CHDs.