title: The effects of birth interval on the birthweights of consecutive, same-sex term siblings.
abstract: OBJECTIVE
  To investigate the effect of birth interval on the relationship between the birthweights of successive siblings.
  
  
  METHODS
  The records of women who had delivered two consecutive, same-sex, live, singletons babies (1983 through 1997) in a private hospital were analysed. The intervals between the birth dates of the siblings were calculated. The first of the siblings was coded Set A and the second, Set B. The ratios of the birthweights (Set B/Set A) were calculated. Comparison of findings was made between various ranges of birth interval.
  
  
  RESULTS
  The birth interval band 24-29 months was associated with the highest mean birthweight for Set B babies and the highest birthweight ratio (p=0.016). Set A babies weighing less than 3000 g were most likely to be outweighed by their Set B siblings (p=0.000001).
  
  
  CONCLUSIONS
  Birth intervals of 24 to 29 months and small size of Set A babies were associated with most significant advantages in birthweight for Set B siblings.
authors.affiliation: Havana Specialist Hospital, P. O. Box 115, Surulere, and Department of Paediatrics, Lagos University Teaching Hospital, Nigeria.
authors.forename: O F
authors.initials: OF
authors.lastname: Njokanma
authors.forename: M T C
authors.initials: MT
authors.lastname: Egri-Okwaji
authors.forename: C A
authors.initials: CA
authors.lastname: Nwokoro
authors.forename: G C E
authors.initials: GC
authors.lastname: Okeke
mesh_terms: D001721:Birth Intervals; D001724:Birth Weight / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009549:Nigeria; D011247:Pregnancy; D012189:Retrospective Studies; D012737:Sex Factors; D035781:Siblings; D013997:Time Factors