title: Epidemiology of neural tube defect subtypes in Tunisia, 1991-2011.
abstract: BACKGROUND
  Neural tube defects are common major congenital anomalies that result from very early disruption in the development of the brain and spinal cord.
  
  
  OBJECTIVE
  We conducted an epidemiological study to determine the impact of some feto-maternal characteristics in the occurrence of NTD subtypes.
  
  
  METHODS
  Characteristics and outcomes of births with NTD and pregnancy characteristics of mothers over a period of twenty years (1991-2011) were recorded in the medical chart.
  
  
  RESULTS
  From 1991 through 2011, 769 stillborns with NTD were delivered, yielding a prevalence of 2.02/10,000. The increase in NTD prevalences over these years was statistically significant (P = 0.000). In addition, differences between prevalences of NTD subtypes over season (P = 0.003) and between genders (P < 0.001) were significant. The highest frequency was noticed in winter with 3, 7 per 10,000 births among females. The difference in fetal term between subtypes was significant (P = 0.017). The probability to have a malformed fetus with a weight less than 1500 g was three times higher in myelomeningocele than in craniorachischisis, two times higher in anencephaly and encephalocele, but two times lower than rachischisis. Mothers with one gestation were two fold higher in anencephaly than in encephalocele. Nulliparous mothers' cases were significantly more likely to have NTD than uni- or multiparous mothers. O+ mother's blood type presented a significant risk factor and was significantly less common in myelomeningocele than in rachischisis, but three times higher than in craniorachischisis. Consanguinity was present in cases with rachischisis and was two times higher than in cases with anencephaly, and three times higher than in cases with encephalocele. In this study, the results have been interpreted with caution due to analyses not being adjusted.
  
  
  CONCLUSIONS
  One of the main findings of the study is that there are many differences between NTD subtypes, which suggests that there may be etiologic differences between subtypes. This suggests that, although epidemiologic studies frequently do not distinguish between NTD subtypes in analyses, they should be analyzed separately when possible.
authors.affiliation: UR 06/SP14 Troubles du développement embryo-fœtal et placentaire, Service d'embryo-foetopathologie, Centre de Maternité et de Néonatologie La Rabta et de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia. Electronic address: nasrikaouther512@gmail.com.
authors.forename: Kaouther
authors.initials: K
authors.lastname: Nasri
authors.affiliation: UR05/08-08, Département de biochimie, Hôpital la Rabta et de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia.
authors.forename: Mohamed Kacem
authors.initials: MK
authors.lastname: Ben Fradj
authors.affiliation: LR99ES11 Laboratoire de recherche et de biochimie clinique, Hopital La Rabta, 1007 Tunis, Tunisia.
authors.forename: Thouraya
authors.initials: T
authors.lastname: Hamdi
authors.affiliation: UR 06/SP14 Troubles du développement embryo-fœtal et placentaire, Service d'embryo-foetopathologie, Centre de Maternité et de Néonatologie La Rabta et de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia.
authors.forename: Mariem
authors.initials: M
authors.lastname: Aloui
authors.affiliation: UR 06/SP14 Troubles du développement embryo-fœtal et placentaire, Service d'embryo-foetopathologie, Centre de Maternité et de Néonatologie La Rabta et de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia.
authors.forename: Nadia
authors.initials: N
authors.lastname: Ben Jemaa
authors.affiliation: UR 06/SP14 Troubles du développement embryo-fœtal et placentaire, Service d'embryo-foetopathologie, Centre de Maternité et de Néonatologie La Rabta et de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia.
authors.forename: Saber
authors.initials: S
authors.lastname: Nahdi
authors.affiliation: UR 06/SP14 Troubles du développement embryo-fœtal et placentaire, Service d'embryo-foetopathologie, Centre de Maternité et de Néonatologie La Rabta et de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia.
authors.forename: Refka
authors.initials: R
authors.lastname: Guesmi
authors.affiliation: UR 06/SP14 Troubles du développement embryo-fœtal et placentaire, Service d'embryo-foetopathologie, Centre de Maternité et de Néonatologie La Rabta et de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia.
authors.forename: Aida
authors.initials: A
authors.lastname: Masmoudi
authors.affiliation: 01/UR/08-07 Laboratoire d'histologie, embryologie et biologie cellulaire de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia.
authors.forename: Michèle Véronique
authors.initials: MV
authors.lastname: Elmay
authors.affiliation: Laboratoire de génétique, immunologie et pathologie humaine, faculté des sciences de Tunis, Université EL Manar, 2092 Tunis, Tunisia.
authors.forename: Raja
authors.initials: R
authors.lastname: Marrakchi
authors.affiliation: UR 06/SP14 Troubles du développement embryo-fœtal et placentaire, Service d'embryo-foetopathologie, Centre de Maternité et de Néonatologie La Rabta et de la Faculté de Médecine de Tunis, Université El Manar, 1007 Tunis, Tunisia.
authors.forename: Soumeya
authors.initials: S
authors.lastname: Siala Gaigi
mesh_terms: D000328:Adult; D000757:Anencephaly / Q000453:epidemiology*; D004677:Encephalocele / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D015995:Prevalence; D012307:Risk Factors; D012737:Sex Factors; D016135:Spinal Dysraphism / Q000453:epidemiology*; D014416:Tunisia / Q000453:epidemiology
keywords: Anencephaly; Encephalocele; Epidemiology; Neural tube defects; Spina bifida