title: Low birthweight and prematurity in relation to paternal factors: a study of recurrence.
abstract: BACKGROUND
  The importance of paternal determinants in the occurrence of low birthweight and prematurity is not well known. We investigated these outcomes in siblings and paternal half siblings as a function of changes in putative external determinants between two births in fathers who had experienced the birth of a premature and/or low birthweight (PTB/LBW) infant.
  
  
  METHODS
  All fathers who, between 1980 and 1992, had an infant born before 37 completed weeks' gestation or weighing <2500 g and a following child were studied. We identified 14 147 pairs of siblings from Danish national registers. The recurrence risk was studied in three sub-cohorts defined by the outcome in the index child (PTB only, PTB/LBW, LBW only). We estimated the recurrence risk in the younger sibling according to changes of female partner, municipality type, occupation, and father's social status.
  
  
  RESULTS
  The overall recurrence risk was 16.7% for preterm delivery and 16.8% for LBW. Changing female partner was, as expected, associated with a reduction in the recurrence risk for both outcomes (RR = 0.40; 95% CI: 0.27-0.60 for preterm delivery and RR = 0.38; 95% CI : 0.26-0.56 for LBW). None of the other studied factors was associated with changes in the recurrence risk. Fathers who changed partner had offspring with similar birthweight and gestational length between the three sub-cohorts, while a difference was evident in offspring to fathers whose female partner was unchanged.
  
  
  CONCLUSIONS
  We did not identify any paternal factor of importance in the occurrence of LBW and preterm delivery.
authors.affiliation: The Danish Epidemiology Science Centre at the Department of Epidemiology and Social Medicine, University of Aarhus. OB@soci.au.dk
authors.forename: O
authors.initials: O
authors.lastname: Basso
authors.forename: J
authors.initials: J
authors.lastname: Olsen
authors.forename: K
authors.initials: K
authors.lastname: Christensen
mesh_terms: D000328:Adult; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007226:Infant Mortality / Q000639:trends; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D009679:Nuclear Family; D007752:Obstetric Labor, Premature / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D018812:Paternal Exposure / Q000009:adverse effects*; D011247:Pregnancy; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors