The rising preterm birth rate in China: a cause for concern

Abstract

Globally, one in ten babies are born preterm, and the preterm birth rate has been increasing.1Chawanpaiboon S Vogel JP Moller A-B et al.Global, regional, and national estimates of levels of preterm birth in 2014: a systematic review and modelling analysis.Lancet Glob Health. 2019; 7: e37-e46Summary Full Text Full Text PDF PubMed Scopus (811) Google Scholar The second highest number of preterm births are reported in China, with more than 1 million babies born preterm every year. Our meta-analysis showed an increase in preterm rate by 1·1% per year from 1990 to 2016.2Jing S Chen C Gan Y Vogel J Zhang J Incidence and trend of preterm birth in China, 1990-2016: a systematic review and meta-analysis.BMJ Open. 2020; 10e039303Crossref PubMed Scopus (6) Google Scholar In the Lancet Global Health, Kui Deng and colleagues3Deng K Liang J Mu Y et al.Preterm births in China between 2012 and 2018: an observational study of more than 9 million women.Lancet Glob Health. 2021; 9: e1226-e1241Summary Full Text Full Text PDF Scopus (4) Google Scholar estimated an increase of 1·3% per year from 2012 to 2018. Their data also suggested that the increasing preterm birth rate might have accelerated after the introduction of the universal two child policy in China. Very preterm births (born between 28 and 31 weeks gestation) showed the highest increase, followed by late preterm births (born between 34 and 36 weeks gestation). The short-term and long-term sequalae of preterm birth are well recognised;4Crump C Sundquist J Winkleby MA Sundquist K Gestational age at birth and mortality from infancy into mid-adulthood: a national cohort study.Lancet Child Adolesc Health. 2019; 3: 408-417Summary Full Text Full Text PDF PubMed Scopus (48) Google Scholar as a result, the large number of annual preterm births combined with a rising trend is a cause for concern. Underlying the increasing number of preterm births is a complex matrix of causes, risk factors, protectors, and confounders. Probably the most prominent and consistent causes for the rise in preterm births are the increasing maternal childbearing age, resulting in more pregnancy complications, and more multiple pregnancies due to an increased use of assistant reproductive technologies. Deng and colleagues3Deng K Liang J Mu Y et al.Preterm births in China between 2012 and 2018: an observational study of more than 9 million women.Lancet Glob Health. 2021; 9: e1226-e1241Summary Full Text Full Text PDF Scopus (4) Google Scholar showed that the increase in very preterm births appeared to have come from singleton pregnancies whereas multiple gestations contributed to an increasing proportion of late preterm births. These two factors might explain why the rates of very early and late preterm births have increased most in China. Low socioeconomic status is a universal risk factor for preterm birth. China is no exception. Low socioeconomic status includes low maternal education, being unmarried while pregnant, attending an inadequate number of prenatal visits (<8 visits), residing in lower income regions, and suboptimal quality of prenatal care (eg, poor capability of early ultrasound scan to assess gestational age).3Deng K Liang J Mu Y et al.Preterm births in China between 2012 and 2018: an observational study of more than 9 million women.Lancet Glob Health. 2021; 9: e1226-e1241Summary Full Text Full Text PDF Scopus (4) Google Scholar, 5Chen C Zhang JW Xia HW et al.Preterm birth in china between 2015 and 2016.Am J Public Health. 2019; 109: 1597-1604Crossref PubMed Scopus (35) Google Scholar Because these factors are often tightly intertwined, ascertaining whether increasing the number of prenatal visits alone can effectively prevent preterm birth in a cross-sectional survey is challenging. More evidence is also needed to support the idea that the decrease in caesareans in China over the past decade has mitigated the rising trend in preterm births because most reductions in caesarean delivery came from full term singleton pregnancies. Nonetheless, the rapid economic development and the government Targeted Poverty Alleviation programmes might have counterbalanced the rising trend of preterm birth over the past decade. There are a wide range of risk factors and precursors for preterm birth. But a large proportion of preterm births still have an unknown cause. For example, our China Labor and Delivery Survey5Chen C Zhang JW Xia HW et al.Preterm birth in china between 2015 and 2016.Am J Public Health. 2019; 109: 1597-1604Crossref PubMed Scopus (35) Google Scholar showed that spontaneous preterm labour accounted for 159 393 (29·5%) of 540 317 preterm births and preterm premature rupture of the fetal membranes for 150 208 (27·8%) of preterm births; 187 035 (34·2%) of all preterm births had no known risk factors at all. The diverse and often obscure causes have made preterm prevention challenging. Nonetheless, some prevention strategies have been found to be effective in previous randomised trials.6Matei A Saccone G Vogel JP Armson AB Primary and secondary prevention of preterm birth: a review of systematic reviews and ongoing randomized controlled trials.Eur J Obstet Gynecol Reprod Biol. 2019; 236: 224-239Summary Full Text Full Text PDF PubMed Scopus (29) Google Scholar For instance, lifestyle and behavioural changes (eg, diet and exercise) can reduce the risk of preterm birth when applied to the general obstetric population as the primary prevention. For secondary prevention targeting individuals at high-risk of preterm birth, low-dose aspirin, progesterone supplementation, and cervical length screening with placement of cerclage and pessary in those with a short cervix can be useful interventions, although the recommendation on progesterone supplementation is being debated.7Medley N Poljak B Mammarella S Alfirevic Z Clinical guidelines for prevention and management of preterm birth: a systematic review.BJOG. 2018; 125: 1361-1369Crossref PubMed Scopus (38) Google Scholar Several studies showed that iatrogenic preterm birth accounted for approximately 40% of all preterm births,5Chen C Zhang JW Xia HW et al.Preterm birth in china between 2015 and 2016.Am J Public Health. 2019; 109: 1597-1604Crossref PubMed Scopus (35) Google Scholar, 8Henderson JJ McWilliam OA Newnham JP Pennell CE Preterm birth aetiology 2004-2008. Maternal factors associated with three phenotypes: spontaneous preterm labour, preterm pre-labour rupture of membranes and medically indicated preterm birth.J Matern Fetal Neonatal Med. 2012; 25: 642-647Crossref PubMed Scopus (61) Google Scholar which was attributable to the increase in iatrogenic late preterm births over the past 20–30 years.8Henderson JJ McWilliam OA Newnham JP Pennell CE Preterm birth aetiology 2004-2008. Maternal factors associated with three phenotypes: spontaneous preterm labour, preterm pre-labour rupture of membranes and medically indicated preterm birth.J Matern Fetal Neonatal Med. 2012; 25: 642-647Crossref PubMed Scopus (61) Google Scholar Because late preterm birth is also associated with suboptimal perinatal and childhood outcomes,4Crump C Sundquist J Winkleby MA Sundquist K Gestational age at birth and mortality from infancy into mid-adulthood: a national cohort study.Lancet Child Adolesc Health. 2019; 3: 408-417Summary Full Text Full Text PDF PubMed Scopus (48) Google Scholar iatrogenic late preterm births should be avoided as much as possible; reducing the number of iatrogenic late preterm births might be another potential area for reduction in preterm births. The goal of tertiary prevention is to minimise adverse sequalae in preterm infants. Steroids for fetal lung maturation and magnesium sulphate for fetal neuroprotection are well established perinatal prophylactics. It is also important to realise that preterm infants are not only premature due to a shorter gestation but might have already had growth and developmental problems in utero. Some of the in utero damage might be reversible through appropriate postnatal nurturing and rehabilitation during the first 1000 days of life.9Lei X Chen Y Ye J Ouyang F Jiang F Zhang J The optimal postnatal growth trajectory for term small for gestational age babies: a prospective cohort study.J Pediatr. 2015; 166: 54-58Summary Full Text Full Text PDF PubMed Scopus (45) Google Scholar From a life-course perspective, it might be beneficial to involve neonatologists and paediatricians early in deciding an appropriate time for birth and making a prenatal and postnatal treatment plan together with obstetricians. In fetuses with congenital anomalies or special conditions, paediatric care before birth, or in utero paediatrics, could be helpful to provide specialised, continuous care and treatment, and follow the future health trajectory of the preterm infants to become healthy adults. Because China has achieved great advances in neonatal care and the survival rate of extreme preterm births has reached a respectable level (eg, the survival rate of neonates born at 26 weeks gestation exceeds 80%),10Qiao J Wang Y Li X et al.A Lancet Commission on 70 years of women's reproductive, maternal, newborn, child, and adolescent health in China.Lancet. 2021; 397: 2497-2536Summary Full Text Full Text PDF PubMed Scopus (28) Google Scholar it is the time for China to consider redefining preterm birth as babies born from 24 weeks (instead of 28 weeks) to 36 weeks of gestation, to make the definition of preterm birth more comparable with high-income countries. We declare no competing interests. Preterm births in China between 2012 and 2018: an observational study of more than 9 million womenAn increase in preterm births was noted for both singleton and multiple pregnancies between 2012 and 2018 in China. China's strategic investment in maternal and neonatal health has been crucial for the prevention of preterm birth. Due to rapid changes in sociodemographic and obstetric factors related to preterm birth—particularly within the context of the universal two child policy—such as advanced maternal age at delivery, maternal complications, and multiple pregnancies, greater efforts to reduce the burden of preterm birth are urgently needed. Full-Text PDF Open Access