title: Do assisted conception twins have an increased risk for anencephaly?
abstract: BACKGROUND
  The incidence rates of anterior neural tube defects, anencephaly and encephalocele appear increased among twins compared with singletons. The current study aimed to evaluate whether the etiology of this phenomenon is related to twinning, assisted reproductive technology (ART), or both.
  
  
  METHODS
  The study cohort consisted of parturient women who were referred to our ultrasonography unit between January 1998 and December 2009 due to suspicion of severe fetal abnormality. The study cohort was divided into two subgroups based on mode of conception: spontaneous and ART (including IVF and ICSI). The subgroups were further subdivided into singleton and multiple pregnancies. We also compared pregnancies diagnosed with anencephaly in the study group to all live births in the Department of Obstetrics and Gynecology.
  
  
  RESULTS
  Anencephaly was diagnosed in 43 fetuses out of 1154 (3.7%) pregnancies diagnosed with severe fetal anomaly. Anencephaly was diagnosed in 9 out of 78 twin pregnancies (11.5%); of these, 8 of 45 (17.8%) were ART conceived and 1 of 33 (3%) spontaneously conceived. A significant correlation was found between twinning and anencephaly, with an odds ratio (OR) of 3.4 [confidence interval (CI) = 1.3-8.9, P= 0.011], while no significant correlation was found between ART and anencephaly. A significant correlation was found between anencephaly and the combination of ART conception and twinning (OR of 6.6, CI = 2.8-15.3, P< 0.01). Analyzing the distribution of pregnancies diagnosed with anencephaly in the study group compared with the total number of live births in the department revealed a significant correlation between twinning and anencephaly, with an OR of 11.4 (CI = 4.9-26.5, P< 0.01), with no significant correlation between ART and anencephaly. Among all live births, a significant correlation was found between anencephaly and the combination of ART conception and twinning (OR of 24.6, CI = 11.4-53.2, P< 0.01).
  
  
  CONCLUSIONS
  Our data suggest that twin pregnancies conceived by ART constitute a high-risk group for anencephaly, due to a possible synergistic effect of twinning and ART.
authors: Department of Obstetrics and Gynecology, Assaf Harofeh Medical Center, affiliated with Sackler School of Medicine, Tel-Aviv University, Zerifin 70300, Israel.
authors: I
authors: I
authors: Ben-Ami
authors: Y
authors: Y
authors: Edel
authors: O
authors: O
authors: Barel
authors: Z
authors: Z
authors: Vaknin
authors: A
authors: A
authors: Herman
authors: R
authors: R
authors: Maymon
mesh_terms: D000328:Adult; D000757:Anencephaly / Q000000981:diagnostic imaging / Q000453:epidemiology*; D015331:Cohort Studies; D004200:Diseases in Twins / Q000000981:diagnostic imaging / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D059285:Pregnancy, Twin; D027724:Reproductive Techniques, Assisted / Q000009:adverse effects*; D012307:Risk Factors; D014463:Ultrasonography