Taiwanese Journal of Obstetrics & Gynecology 53 (2014) 285e286
Contents lists available at ScienceDirect
Taiwanese Journal of Obstetrics & Gynecology journal homepage: www.tjog-online.com
Editorial
Late preterm births: An important issue but often neglected Preterm birth, defined as birth before 37 full weeks, is still the leading cause of mortality and morbidity in the neonatal period and a major cause of these outcomes in childhood [1]. However, most studies have focused on premature infants born before 32 weeks of gestation, partly because these premature infants are obviously at the greatest risk, and partly because earlier reports showed a gain in survival and a decreased risk of complications and/or sequelae for each additional week of gestation between 22 and 32 weeks, but that the benefits become less important and more difficult to detect beyond 33 to 34 weeks [2,3]. A publication by Lu et al entitled “Risk factors associated with late preterm births in the undeveloped region of China: a cohort study and systematic review”, attracted our attention. Many obstetricians have a greater tolerance for interrupting the pregnancy when there are maternal and/or fetal complications beyond 34 weeks of gestation [4], because in the past these newborns were considered “near term or almost term” based on normal birth weight and size, and they were treated as if they were functionally full term. Despite having a lower risk than premature infants born before 34 weeks of gestation, preterm infants born between 34 and 36 weeks have a much higher risk of death and complications than those born at term, as shown in many studies [1,5e7]. Therefore, the term “late preterm birth” needs to be defined, including infants born at 34 to 36 weeks and 6 days of gestational age [1]. Lu et al's study investigated infants newly born between 2004 and 2008 in western Sichuan Province, China, and the major findings included (1) the percentage of late preterm births was 7.4% (range 6.4e8.0%), which is significantly lower than those in Western countries (9.1% in 2005) and Africa (12.3% in 2009), but higher than in other Chinese areas, such as Zhejiang province (6.2% in 2007) and Beijing (2.7% in 2007); (2) teenage (< 20 years of age) and older ( 35 years) mothers had a higher risk of late preterm births; (3) mothers with multiple gestations had the highest risk; (4) the lower frequency of regular prenatal care contributed to the high risk of late preterm births [1]. In addition, the data from Lu et al's systematic review [1] indicated that incidence of late preterm births ranged from 4.4% to 16%, and the most prominent risk factors were twin gestation, gestational diabetes mellitus, eclampsia and preeclampsia, placenta previa, placental abruption, and premature rupture of the membranes. This original study raised at least three important issues: (1) the range of variability of late preterm birth risks among ethnic and socioeconomic groups; (2) women's age; (3) maternal health and multiple pregnancies. First, it may be difficult to estimate the percentage of late preterm births. For example, Bassil et al [7] reported 5.4%, which was calculated based on all births between 34 and 40 weeks (49,157/
917,013), but the reports of the Centers for Disease Control and Prevention (CDC) in the United States were 9.1% in 2006 and 8.5% in 2010, respectively [8]. The calculation of the CDC is based on per 100 total births in a given category [8], suggesting a given category decided the percentage of preterm births or late preterm births. Therefore, different methods might result in different percentages of late preterm births. Second, the report of the CDC also confirmed the persistence of substantial differences in preterm birth rates by race/ethnicity, but the rate of late preterm births declined among each of the race/ ethnicity groups during 2006e2010 [8]. In 2010, black infants (11.9% in 2006 and 11.0% in 2010) were approximately 40% more likely to be born late preterm than white and Asian/Pacific Islander infants (8.1% in 2006 and 7.8% in 2010). American Indian/Alaska Native (10.2% in 2006 and 9.6% in 2010) and Hispanic infants (8.8% in 2006 and 8.5% in 2010) also were more likely than white and Asian/Pacific Islander infants to be born late preterm. And what about the late preterm birth rate in Taiwan? The study by Tsai et al [9] reported 11.4% (914/7998 live births) in a medical center in northern Taiwan between 2008 and 2009 [9]. By contrast, Alibekova et al [10] used two large nationwide population-based datasets, the National Health Insurance Research Database [11] and Taiwan Birth Certificate Registry [12], to show that the rate of preterm births was 7.2% (1080/15,056) and 6.6% (3975/60,224) among women with and without a diagnosis of infertility, respectively, suggesting that the percentage of late preterm births might be much lower. Just as Lu et al mentioned, the reasons for these differences are not clear. However, disparities among groups might be related to differences in socioeconomic status, prenatal care, maternal risky behaviors, infection, nutrition, preconception stress, and genetics [8]. Third, it is not fair to consider complicated pregnancy, such as preeclampsia, eclampsia, or placental abruption as risk factors for late preterm births, because some of these risk factors might result in either or both maternal or fetal morbidity or mortality. In cases of complicated pregnancy, delivery cannot be totally avoided, so preterm births, including late preterm births, occur. Therefore, improving women's health during pregnancy or decreasing the incidence of these complicated pregnancies is important. Many of the complications, unfortunately, cannot be prevented, although factors associated with inadequate prenatal care may be predictors of pregnancy outcome in pregnant women with preeclampsia [13]. Preterm birth risk could be reduced by close monitoring and/or frequent follow-up of women with a history of child death and antenatal complications, as shown in Lu et al's study [1]. One study [13] showed that the risk of preterm birth was lower among women with primary or higher levels of education [relative risk
http://dx.doi.org/10.1016/j.tjog.2014.07.002 1028-4559/Copyright © 2014, Taiwan Association of Obstetrics & Gynecology. Published by Elsevier Taiwan LLC. All rights reserved.
286
Editorial / Taiwanese Journal of Obstetrics & Gynecology 53 (2014) 285e286
(RR): 0.92; 95% confidence interval (CI): 0.88, 0.97], women who sought antenatal care at least once during the index pregnancy (RR: 0.86; 95% CI: 0.83, 0.90), and women who had completed all birth preparedness steps (RR: 0.32; 95% CI: 0.30, 0.34). Finally, advanced maternal age might also be an important factor for late preterm births or other adverse outcomes [14,15]. Older mothers are at risk of both a worse outcome for themselves and a poor neonatal outcome. Lu et al's study also showed the increased risk of a late preterm birth of mothers 35 years of age [odds ratio (OR): 1.87], compared to those with a maternal age of 20e34.9 years [1]. However, for teenage mothers, data are not always consistent. In Lu et al's study, risk was increased in teenage mothers (OR 3.81), but this increased risk was not found in the African study (RR: 0.97; 95% CI: 0.87, 1.09). Strong evidence has shown that adolescents should be taken seriously, an adolescent indicator should be included in all monitoring mechanisms for women's and children's health, and young people meaningfully involved with all policymaking bodies affecting women and children. Prevention of stillbirths and neonatal mortality and morbidity must include great attention to teenage girls in particular, because those so-called “teenage mothers” who are in fact children bearing children, including 16 million girls aged 15e19 years and 2 million younger than 15 years, have a greater risk of adverse maternal and birth outcomes, such as prenatal, neonatal, and postnatal deaths, preterm births, small-for-gestational-age babies, and complications during birth than do those older than 19 years [16]. Conflicts of interest
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
gestational age and biological determinants of preterm birth. Int J Epidemiol 2014;43:802e14. Bassil KL, Yasseen 3rd AS, Walker M, Sgro MD, Shah PS, Smith GN, et al. The association between obstetrical interventions and late preterm birth. Am J Obstet Gynecol 2014;210:538. Martin JA, Osterman MJ, Centers for Disease Control and Prevention (CDC). Preterm births e United States, 2006 and 2010. MMWR Surveill Summ 2013;62(3):136e8. Tsai ML, Lien R, Chiang MC, Hsu JF, Fu RH, Chu SM, et al. Prevalence and morbidity of late preterm infants: current status in a medical center of Northern Taiwan. Pediatr Neonatol 2012;53:171e7. Alibekova R, Huang JP, Chen YH. Adequate prenatal care reduces the risk of adverse pregnancy outcomes in women with history of infertility: a nationwide population-based study. PLoS One 2013;8:e84237. Jou HJ, Siao RY, Tsai YS, Chen YT, Li CY, Chen CC. Postdischarge rehospitalization and in-hospital mortality among Taiwanese women with hip fracture. Taiwan J Obstet Gynecol 2014;53:43e7. Wang PH, Chen CY, Lee CN. Taiwan birth weight reference. J Chin Med Assoc 2014 Aug 20. pii: S1726-4901(14)00174-9. http://dx.doi.org/10.1016/j.jcma. 2014.07.002. [Epub ahead of print]. Liu CM, Chang SD, Cheng PJ. Relationship between prenatal care and maternal complications in women with preeclampsia: implications for continuity and discontinuity of prenatal care. Taiwan J Obstet Gynecol 2012;51:576e82. Chang YW, Chen LC, Chen CY, Yeh CC, Cheng LY, Lai YL, et al. Robertsonian translocations: an overview of a 30-year experience in a single tertiary medical center in Taiwan. J Chin Med Assoc 2013;76:335e9. Chang YW, Chang CM, Sung PL, Yang MJ, Li WH, Li HY, et al. An overview of a 3-year experience with amniocentesis in a single tertiary medical center in Taiwan. Taiwan J Obstet Gynecol 2012;51:206e11. Every newborn, every mother, every adolescent girl. Lancet 2014;383:755.
Peng-Hui Peter Wang* Division of Gynecology, Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan Immunology Center, Taipei Veterans General Hospital, Taipei, Taiwan
The authors have no conflicts of interest relevant to this article.
Department of Obstetrics and Gynecology, National Yang-Ming University, Taipei, Taiwan
Acknowledgments This study was supported in part by grants from the National Science Council of Taiwan (NSC 102-2314-B-010-032) and Taipei Veterans General Hospital (V103C-112; V103E4-003).
Department of Medical Research, China Medical University, Taichung, Taiwan Chih-Yao Chen Division of Gynecology, Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan
References [1] Machado Júnior LC, Passini Júnior R, Rodrigues Machado Rosa I. Late prematurity: a systematic review. J Pediatr (Rio J) 2014;90:221e31. [2] Goldenberg RL, Nelson KG, Davis RO, Koski J. Delay in delivery: influence of gestational age and the duration of delay on perinatal outcome. Obstet Gynecol 1984;64:480e4. [3] DePalma RT, Leveno KJ, Kelly MA, Sherman ML, Carmody TJ. Birth weight threshold for postponing preterm birth. Am J Obstet Gynecol 1992;167:1145e9. [4] Fuchs K, Gyamfi C. The influence of obstetric practices on late prematurity. Clin Perinatol 2008;35:343e60. [5] Soilly AL, Lejeune C, Quantin C, Bejean S, Gouyon JB. Economic analysis of the costs associated with prematurity from a literature review. Public Health 2014;128:43e62. [6] Brown HK, Speechley KN, Macnab J, Natale R, Campbell MK. Neonatal morbidity associated with late preterm and early term birth: the roles of
Department of Obstetrics and Gynecology, National Yang-Ming University, Taipei, Taiwan Chien-Nan Lee Department of Obstetrics and Gynecology, National Taiwan University, Hospital and National Taiwan University, Taipei, Taiwan *
Corresponding author. Division of Gynecology, Department of Obstetrics and Gynecology, National Yang-Ming University and Taipei Veterans General Hospital, Taipei, Taiwan. E-mail addresses: [email protected], [email protected] (P.-H.P. Wang).
Contents lists available at ScienceDirect
Taiwanese Journal of Obstetrics & Gynecology journal homepage: www.tjog-online.com
Editorial
Late preterm births: An important issue but often neglected Preterm birth, defined as birth before 37 full weeks, is still the leading cause of mortality and morbidity in the neonatal period and a major cause of these outcomes in childhood [1]. However, most studies have focused on premature infants born before 32 weeks of gestation, partly because these premature infants are obviously at the greatest risk, and partly because earlier reports showed a gain in survival and a decreased risk of complications and/or sequelae for each additional week of gestation between 22 and 32 weeks, but that the benefits become less important and more difficult to detect beyond 33 to 34 weeks [2,3]. A publication by Lu et al entitled “Risk factors associated with late preterm births in the undeveloped region of China: a cohort study and systematic review”, attracted our attention. Many obstetricians have a greater tolerance for interrupting the pregnancy when there are maternal and/or fetal complications beyond 34 weeks of gestation [4], because in the past these newborns were considered “near term or almost term” based on normal birth weight and size, and they were treated as if they were functionally full term. Despite having a lower risk than premature infants born before 34 weeks of gestation, preterm infants born between 34 and 36 weeks have a much higher risk of death and complications than those born at term, as shown in many studies [1,5e7]. Therefore, the term “late preterm birth” needs to be defined, including infants born at 34 to 36 weeks and 6 days of gestational age [1]. Lu et al's study investigated infants newly born between 2004 and 2008 in western Sichuan Province, China, and the major findings included (1) the percentage of late preterm births was 7.4% (range 6.4e8.0%), which is significantly lower than those in Western countries (9.1% in 2005) and Africa (12.3% in 2009), but higher than in other Chinese areas, such as Zhejiang province (6.2% in 2007) and Beijing (2.7% in 2007); (2) teenage (< 20 years of age) and older ( 35 years) mothers had a higher risk of late preterm births; (3) mothers with multiple gestations had the highest risk; (4) the lower frequency of regular prenatal care contributed to the high risk of late preterm births [1]. In addition, the data from Lu et al's systematic review [1] indicated that incidence of late preterm births ranged from 4.4% to 16%, and the most prominent risk factors were twin gestation, gestational diabetes mellitus, eclampsia and preeclampsia, placenta previa, placental abruption, and premature rupture of the membranes. This original study raised at least three important issues: (1) the range of variability of late preterm birth risks among ethnic and socioeconomic groups; (2) women's age; (3) maternal health and multiple pregnancies. First, it may be difficult to estimate the percentage of late preterm births. For example, Bassil et al [7] reported 5.4%, which was calculated based on all births between 34 and 40 weeks (49,157/
917,013), but the reports of the Centers for Disease Control and Prevention (CDC) in the United States were 9.1% in 2006 and 8.5% in 2010, respectively [8]. The calculation of the CDC is based on per 100 total births in a given category [8], suggesting a given category decided the percentage of preterm births or late preterm births. Therefore, different methods might result in different percentages of late preterm births. Second, the report of the CDC also confirmed the persistence of substantial differences in preterm birth rates by race/ethnicity, but the rate of late preterm births declined among each of the race/ ethnicity groups during 2006e2010 [8]. In 2010, black infants (11.9% in 2006 and 11.0% in 2010) were approximately 40% more likely to be born late preterm than white and Asian/Pacific Islander infants (8.1% in 2006 and 7.8% in 2010). American Indian/Alaska Native (10.2% in 2006 and 9.6% in 2010) and Hispanic infants (8.8% in 2006 and 8.5% in 2010) also were more likely than white and Asian/Pacific Islander infants to be born late preterm. And what about the late preterm birth rate in Taiwan? The study by Tsai et al [9] reported 11.4% (914/7998 live births) in a medical center in northern Taiwan between 2008 and 2009 [9]. By contrast, Alibekova et al [10] used two large nationwide population-based datasets, the National Health Insurance Research Database [11] and Taiwan Birth Certificate Registry [12], to show that the rate of preterm births was 7.2% (1080/15,056) and 6.6% (3975/60,224) among women with and without a diagnosis of infertility, respectively, suggesting that the percentage of late preterm births might be much lower. Just as Lu et al mentioned, the reasons for these differences are not clear. However, disparities among groups might be related to differences in socioeconomic status, prenatal care, maternal risky behaviors, infection, nutrition, preconception stress, and genetics [8]. Third, it is not fair to consider complicated pregnancy, such as preeclampsia, eclampsia, or placental abruption as risk factors for late preterm births, because some of these risk factors might result in either or both maternal or fetal morbidity or mortality. In cases of complicated pregnancy, delivery cannot be totally avoided, so preterm births, including late preterm births, occur. Therefore, improving women's health during pregnancy or decreasing the incidence of these complicated pregnancies is important. Many of the complications, unfortunately, cannot be prevented, although factors associated with inadequate prenatal care may be predictors of pregnancy outcome in pregnant women with preeclampsia [13]. Preterm birth risk could be reduced by close monitoring and/or frequent follow-up of women with a history of child death and antenatal complications, as shown in Lu et al's study [1]. One study [13] showed that the risk of preterm birth was lower among women with primary or higher levels of education [relative risk
http://dx.doi.org/10.1016/j.tjog.2014.07.002 1028-4559/Copyright © 2014, Taiwan Association of Obstetrics & Gynecology. Published by Elsevier Taiwan LLC. All rights reserved.
286
Editorial / Taiwanese Journal of Obstetrics & Gynecology 53 (2014) 285e286
(RR): 0.92; 95% confidence interval (CI): 0.88, 0.97], women who sought antenatal care at least once during the index pregnancy (RR: 0.86; 95% CI: 0.83, 0.90), and women who had completed all birth preparedness steps (RR: 0.32; 95% CI: 0.30, 0.34). Finally, advanced maternal age might also be an important factor for late preterm births or other adverse outcomes [14,15]. Older mothers are at risk of both a worse outcome for themselves and a poor neonatal outcome. Lu et al's study also showed the increased risk of a late preterm birth of mothers 35 years of age [odds ratio (OR): 1.87], compared to those with a maternal age of 20e34.9 years [1]. However, for teenage mothers, data are not always consistent. In Lu et al's study, risk was increased in teenage mothers (OR 3.81), but this increased risk was not found in the African study (RR: 0.97; 95% CI: 0.87, 1.09). Strong evidence has shown that adolescents should be taken seriously, an adolescent indicator should be included in all monitoring mechanisms for women's and children's health, and young people meaningfully involved with all policymaking bodies affecting women and children. Prevention of stillbirths and neonatal mortality and morbidity must include great attention to teenage girls in particular, because those so-called “teenage mothers” who are in fact children bearing children, including 16 million girls aged 15e19 years and 2 million younger than 15 years, have a greater risk of adverse maternal and birth outcomes, such as prenatal, neonatal, and postnatal deaths, preterm births, small-for-gestational-age babies, and complications during birth than do those older than 19 years [16]. Conflicts of interest
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
gestational age and biological determinants of preterm birth. Int J Epidemiol 2014;43:802e14. Bassil KL, Yasseen 3rd AS, Walker M, Sgro MD, Shah PS, Smith GN, et al. The association between obstetrical interventions and late preterm birth. Am J Obstet Gynecol 2014;210:538. Martin JA, Osterman MJ, Centers for Disease Control and Prevention (CDC). Preterm births e United States, 2006 and 2010. MMWR Surveill Summ 2013;62(3):136e8. Tsai ML, Lien R, Chiang MC, Hsu JF, Fu RH, Chu SM, et al. Prevalence and morbidity of late preterm infants: current status in a medical center of Northern Taiwan. Pediatr Neonatol 2012;53:171e7. Alibekova R, Huang JP, Chen YH. Adequate prenatal care reduces the risk of adverse pregnancy outcomes in women with history of infertility: a nationwide population-based study. PLoS One 2013;8:e84237. Jou HJ, Siao RY, Tsai YS, Chen YT, Li CY, Chen CC. Postdischarge rehospitalization and in-hospital mortality among Taiwanese women with hip fracture. Taiwan J Obstet Gynecol 2014;53:43e7. Wang PH, Chen CY, Lee CN. Taiwan birth weight reference. J Chin Med Assoc 2014 Aug 20. pii: S1726-4901(14)00174-9. http://dx.doi.org/10.1016/j.jcma. 2014.07.002. [Epub ahead of print]. Liu CM, Chang SD, Cheng PJ. Relationship between prenatal care and maternal complications in women with preeclampsia: implications for continuity and discontinuity of prenatal care. Taiwan J Obstet Gynecol 2012;51:576e82. Chang YW, Chen LC, Chen CY, Yeh CC, Cheng LY, Lai YL, et al. Robertsonian translocations: an overview of a 30-year experience in a single tertiary medical center in Taiwan. J Chin Med Assoc 2013;76:335e9. Chang YW, Chang CM, Sung PL, Yang MJ, Li WH, Li HY, et al. An overview of a 3-year experience with amniocentesis in a single tertiary medical center in Taiwan. Taiwan J Obstet Gynecol 2012;51:206e11. Every newborn, every mother, every adolescent girl. Lancet 2014;383:755.
Peng-Hui Peter Wang* Division of Gynecology, Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan Immunology Center, Taipei Veterans General Hospital, Taipei, Taiwan
The authors have no conflicts of interest relevant to this article.
Department of Obstetrics and Gynecology, National Yang-Ming University, Taipei, Taiwan
Acknowledgments This study was supported in part by grants from the National Science Council of Taiwan (NSC 102-2314-B-010-032) and Taipei Veterans General Hospital (V103C-112; V103E4-003).
Department of Medical Research, China Medical University, Taichung, Taiwan Chih-Yao Chen Division of Gynecology, Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei, Taiwan
References [1] Machado Júnior LC, Passini Júnior R, Rodrigues Machado Rosa I. Late prematurity: a systematic review. J Pediatr (Rio J) 2014;90:221e31. [2] Goldenberg RL, Nelson KG, Davis RO, Koski J. Delay in delivery: influence of gestational age and the duration of delay on perinatal outcome. Obstet Gynecol 1984;64:480e4. [3] DePalma RT, Leveno KJ, Kelly MA, Sherman ML, Carmody TJ. Birth weight threshold for postponing preterm birth. Am J Obstet Gynecol 1992;167:1145e9. [4] Fuchs K, Gyamfi C. The influence of obstetric practices on late prematurity. Clin Perinatol 2008;35:343e60. [5] Soilly AL, Lejeune C, Quantin C, Bejean S, Gouyon JB. Economic analysis of the costs associated with prematurity from a literature review. Public Health 2014;128:43e62. [6] Brown HK, Speechley KN, Macnab J, Natale R, Campbell MK. Neonatal morbidity associated with late preterm and early term birth: the roles of
Department of Obstetrics and Gynecology, National Yang-Ming University, Taipei, Taiwan Chien-Nan Lee Department of Obstetrics and Gynecology, National Taiwan University, Hospital and National Taiwan University, Taipei, Taiwan *
Corresponding author. Division of Gynecology, Department of Obstetrics and Gynecology, National Yang-Ming University and Taipei Veterans General Hospital, Taipei, Taiwan. E-mail addresses: [email protected], [email protected] (P.-H.P. Wang).
