title: [Comparative study of pregnancy outcomes between spontaneous twin pregnancies and twin pregnancies after fetal reduction in the second trimester].
abstract: OBJECTIVE
  To compare the outcomes of multifetal pregnancy reduced to twins with initial twin pregnancy.
  
  
  METHODS
  This study included all patients who had high-order multiple pregnancies from August 2007 to September 2010 (n = 567) in outpatient or inpatient of Department of Obstetrics and Gynecology, Provincial Hospital Affiliated to Shandong University. There were 478 initial twin pregnancy (non-reduced group) and 89 multifetal pregnancy reduced to twins (reduced group). All fetal reduction procedures were performed after 12 weeks gestation. The maternal ages, gestational ages at delivery, pregnancy complications, birth weight of twins and neonatal outcomes were observed in all groups.
  
  
  RESULTS
  (1) Average maternal ages and mean gestational ages at delivery: the average maternal ages were (29.7 ± 4.5) and (29.9 ± 5.0) years for the non-reduced and reduced groups, respectively, no statistical significance (P = 0.755). The mean gestational ages at delivery in the nonreduced and reduced twins were (35.3 ± 3.9) and (34.4 ± 6.3) weeks, respectively (P < 0.01). (2) Pregnancy complications:the rate of pre-eclampsia was 8.2% (39/478) in the nonreduced group and 12.4% (11/89) in the reduced group, no statistical significance (P = 0.199). The rates of gestational diabetes mellitus were 1.7% (8/478) and 3.4% (3/89), respectively, no statistical significance (P = 0.287). (3) Neonatal outcomes: 1) the frequencies of birth weight discordances > 400 g were 28.9% for the nonreduced group and 27.0% for the reduced group, no statistical significance (P = 0.715). The frequencies of birth weight discordances > 100 g were 75.1% for the nonreduced group and 75.3% for the reduced group, no statistical significance (P = 0.972). 2) The mean birth weight of the nonreduced twin group was significantly higher than that of the reduced group [(2700 ± 468) g vs. (2352 ± 602) g, respectively, P < 0.01], there was statistical significance. The mean birth weight of gestational ages > 36(+1) weeks at delivery of the nonreduced twin group was significantly higher than that of the reduced group [(2809 ± 424) g vs. (2707 ± 506) g, respectively, P < 0.01], there is statistical significance. 3) The rate of infant mortality (gestational ages > 28 weeks at delivery) was 1.3% (1/78) for the reduced group and 2.2% (10/448) for the nonreduced group. The major morbidity rate was 3.8% (3/78) for the reduced group and 4.0% (18/448) for the nonreduced group, no statistical significance (P = 0.588, 0.943).
  
  
  CONCLUSIONS
  Multiple pregnancies after fetal reduction were still associated with a mild increased risk when compared to initial twin pregnancies and their abortion rate is high. The gestational ages of the reduced group were affected by the initial number of fetuses, and the birth weights of reduced twins were lower than that of the nonreduced twins.
authors.affiliation: Department of Obstetrics and Gynecology, Shandong University, Jinan, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Hong-yan
authors.initials: HY
authors.lastname: Li
authors.forename: Xie-tong
authors.initials: XT
authors.lastname: Wang
authors.forename: Hai-yan
authors.initials: HY
authors.lastname: Hou
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008423:Maternal Age; D011225:Pre-Eclampsia; D011247:Pregnancy; D011248:Pregnancy Complications; D011256:Pregnancy Outcome; D018607:Pregnancy Reduction, Multifetal; D011262:Pregnancy Trimester, Second; D011272:Pregnancy, Multiple; D059285:Pregnancy, Twin; D014427:Twins