title: Maximum number of children per sperm donor based on false paternity rate.
abstract: OBJECTIVE
  The aim of this study is to estimate the weight of each relevant factor in such unions of inadvertent consanguinity and to determine a "reasonable" limit for the number of children per donor, matching the probability of inadvertent consanguinity arising from the use of sperm donor in assisted reproduction with that of such a union arising from false paternity.
  
  
  METHODS
  In this study, we applied to Spanish data a mathematical model of consanguineous unions, taking into account the following factors: maximum number of live births/donor, fertility rate, average number of births per donor in a pregnancy, donor success rate, matings per phenotype, number of newborns/year, and number of donors needed in the population/year and births by false paternity.
  
  
  RESULTS
  In Spain, the number of inadvertent unions between descendants of the same donor in Spain has been estimated at 0.4/year (one every two and a half years), although this frequency decreases as the reference population increases. On the other hand, the frequency of unions between family members due to false paternity has been estimated at 6.1/year. Thus, only 6% of such unions are due to the use of donor sperm.
  
  
  CONCLUSIONS
  A total of 25 children per sperm donor are needed to align the probability of inadvertant consanguinity arising from the use of assisted reproduction with that due to false paternity. Therefore, we consider this number to be the maximum "reasonable" number of children born per donor in Spain.
authors.affiliation: Unidad de Reproducción Humana, UGC Laboratorio Clínico y UGC Obstetricia y Ginecología, CHU Granada, Instituto de Investigación Biosanitaria de Granada (IIBG), Granada, Spain.
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Sánchez-Castelló
authors.affiliation: Unidad de Reproducción Humana, UGC Laboratorio Clínico y UGC Obstetricia y Ginecología, CHU Granada, Instituto de Investigación Biosanitaria de Granada (IIBG), Granada, Spain.
authors.forename: María C
authors.initials: MC
authors.lastname: Gonzalvo
authors.affiliation: Unidad de Reproducción Humana, UGC Laboratorio Clínico y UGC Obstetricia y Ginecología, CHU Granada, Instituto de Investigación Biosanitaria de Granada (IIBG), Granada, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Clavero
authors.affiliation: Unidad de Reproducción Humana, UGC Laboratorio Clínico y UGC Obstetricia y Ginecología, CHU Granada, Instituto de Investigación Biosanitaria de Granada (IIBG), Granada, Spain. marisalopezregalado@gmail.com.
authors.forename: María L
authors.initials: ML
authors.lastname: López-Regalado
authors.affiliation: Unidad de Reproducción Humana, UGC Laboratorio Clínico y UGC Obstetricia y Ginecología, CHU Granada, Instituto de Investigación Biosanitaria de Granada (IIBG), Granada, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Mozas
authors.affiliation: Unidad de Reproducción Humana, UGC Laboratorio Clínico y UGC Obstetricia y Ginecología, CHU Granada, Instituto de Investigación Biosanitaria de Granada (IIBG), Granada, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Granados
authors.affiliation: Unidad de Reproducción Humana, UGC Laboratorio Clínico y UGC Obstetricia y Ginecología, CHU Granada, Instituto de Investigación Biosanitaria de Granada (IIBG), Granada, Spain.
authors.forename: Purificación
authors.initials: P
authors.lastname: Navas
authors.affiliation: Unidad de Reproducción Humana, UGC Laboratorio Clínico y UGC Obstetricia y Ginecología, CHU Granada, Instituto de Investigación Biosanitaria de Granada (IIBG), Granada, Spain.|CEIFER Biobanco and Clinica MasVida Reproducción, Granada, Spain.|Dpto. Anatomía y Embriología Humana, F. Medicina, U. Granada, Granada, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Castilla
mesh_terms: D003241:Consanguinity; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D050498:Live Birth / Q000453:epidemiology; D008297:Male; D008962:Models, Theoretical; D010334:Paternity; D011247:Pregnancy; D027724:Reproductive Techniques, Assisted; D013030:Spain; D013094:Spermatozoa; D014019:Tissue Donors
keywords: Consanguinity; False paternity; Maximum number of children per donor; Unions between family members