title: [Appropriate delivery mode and timing of termination for pregnancy with low birth weight infants].
abstract: OBJECTIVE
  To investigate the delivery mode and perinatal outcomes of low birth weight infants in mainland China, and to explore the appropriate delivery mode and timing of delivery.
  
  
  METHODS
  Clinical data of 103 678 babies delivered from Jan 1(st) to Dec 31(th), 2011 in 39 hospitals in mainland China were analyzed retrospectively. The 39 hospitals located in 7 administrative regions, including Northeast, Northwest, North, Central, East, South and Southwest China.
  
  
  RESULTS
  (1) The average birth weight of the newborns was (3 263 ± 540) g. Among them, 7 474 cases were diagnosed low birth weight infants, with the incidence of 7.209% (7 474/103 678). There were 2.328% (2 214/95 116) full-term low birth weight infants and 61.434% (5 260/8 562) preterm low birth weight infants. (2) From week 28 to week 36, the cesarean section rate of low birth weight infants increased with the increasing of gestational weeks. The cesarean section rate of full-term low birth weight infants were 61.14% (1 139/1 863), which was higher than that of normal birth weight infants (52.947%, 45 108/85 195). The differences were statistically significant (P < 0.01). (3) The constitution of the indication of cesarean section showed that social factor and maternal factor were 10.73% (443/4 128) and 48.91% (2 019/4 128) for low birth weight infants, respectively. While for the normal birth weight infants, they were 27.70% (12 495/45 108) and 38.60% (17 412/45 108), respectively. There was statistically significant difference (P < 0.01). (4) The emergency cesarean section rate of full-term low birth weight infants was 41.09% (468/1 139), which was higher than that of normal birth weight infants (31.09%, 14 024/45 108). The difference was statistically significant (P < 0.01). (5) The rates of stillbirth, neonatal asphyxia and the mortality of full-term low birth weight infants were 2.36% (44/1 863), 6.12% (114/1 863), and 3.17% (59/1 863), respectively. Those of normal birth weight infants were 0.11% (94/85 195), 1.41% (1 201/85 195), and 0.14% (119/85 195), respectively. The differences were statistically significant (P < 0.01). (6) The stillbirth rate and mortality of low birth weight infants born by cesarean delivery were significantly lower than those born by vaginal delivery. The rate of neonatal asphyxia (17.95%) and other morbidity (3.61%) among low birth weight infants born by cesarean section in week 28 to week 33(+6) were significantly lower than those born by vaginal delivery (30.09%, 6.62%, respectively). (7) With the increase of gestational age, the incidence of neonatal asphyxia and stillbirth decreased. The incidence of neonatal asphyxia (39.22%) and stillbirth (23.28%) was most seen in 28 to 29 gestational weeks, which decreased to 9.08% and 2.88% in 34 gestation weeks.
  
  
  CONCLUSIONS
  Low birth weight is one of the leading causes of adverse perinatal outcomes and cesarean section. To decrease the incidence of low birth weight, individualized management should be performed according to the gestational age and fetal condition. Extending the gestational age to at least 34 weeks may avoid iatrogenic preterm labor and improve the neonatal survival rate.
authors: Department of Obstetrics, Beijing Obstetric and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors: Yi
authors: Y
authors: Chen
authors: Department of Obstetrics, Beijing Obstetric and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors: Liying
authors: L
authors: Zou
authors: Department of Obstetrics, Beijing Obstetric and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors: Guanghui
authors: G
authors: Li
authors: Department of Obstetrics, Beijing Obstetric and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors: Yan
authors: Y
authors: Ruan
authors: Department of Obstetrics, Beijing Obstetric and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors: Xin
authors: X
authors: Wang
authors: Department of Obstetrics, Beijing Obstetric and Gynecology Hospital, Capital Medical University, Beijing 100026, China; Email: zhangwy9921@hotmail.com.
authors: Weiyuan
authors: W
authors: Zhang
mesh_terms: D001238:Asphyxia Neonatorum / Q000453:epidemiology / Q000209:etiology; D001724:Birth Weight; D002585:Cesarean Section / Q000706:statistics & numerical data*; D002681:China / Q000453:epidemiology; D036861:Delivery, Obstetric / Q000379:methods*; D005260:Female; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007223:Infant; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007743:Labor, Obstetric / Q000502:physiology*; D007752:Obstetric Labor, Premature; D011247:Pregnancy; D012189:Retrospective Studies; D013997:Time Factors