title: Factors in the regulation of fertility in deprived populations.
abstract: BACKGROUND
  Real differences in the duration of post-partum amenorrhoea for similar breastfeeding practices are observed in different populations.
  
  
  OBJECTIVE
  The present study investigated the role of energetics in the regulation of fertility among lactating women with high levels of physical activity and poor nutritional status.
  
  
  METHODS
  From 1996 to 1998, we carried out a longitudinal survey on the factors regulating fertility in lactating women. All women in our sample (n=150) had poor nutritional status and high levels of physical activity, and most of them were illiterate. Half of them were tea workers, and the other half were housewives of male tea workers. They lived in the same villages inside the tea plantation, and were highly comparable.
  
  
  RESULTS
  Survival analysis revealed a very significant longer median duration of post-partum amenorrhoea for tea workers (636 days) compared with non-workers (375 days) although the tea workers cannot breastfeed during the working day. These durations are much longer than those of the WHO multinational study, carried out with a similar protocol, where the medians ranged between 122 and 282 days.
  
  
  CONCLUSIONS
  We suggest that our findings highlight the effect of energetics on the regulation of fertility in lactating women.
authors.affiliation: Centre National de la Recherche Scientifique, CNRS UPR 2147, Paris, France. lyliane.rosetta@evolhum.cnrs.fr
authors.forename: L
authors.initials: L
authors.lastname: Rosetta
authors.forename: C G N
authors.initials: CG
authors.lastname: Mascie-Taylor
mesh_terms: D000328:Adult; D000568:Amenorrhea / Q000453:epidemiology; D001459:Bangladesh / Q000453:epidemiology; D005260:Female; D005298:Fertility / Q000502:physiology*; D006304:Health Status; D006801:Humans; D007223:Infant; D007774:Lactation; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity; D015996:Survival Rate