title: Seasonality of birth outcomes in rural Sarlahi District, Nepal: a population-based prospective cohort.
abstract: BACKGROUND
  While seasonality of birth outcomes has been documented in a variety of settings, data from rural South Asia are lacking. We report a descriptive study of the seasonality of prematurity, low birth weight, small for gestational age, neonatal deaths, and stillbirths in the plains of Nepal.
  
  
  METHODS
  Using data collected prospectively during a randomized controlled trial of neonatal skin and umbilical cord cleansing with chlorhexidine, we analyzed a cohort of 23,662 babies born between September 2002 and January 2006. Project workers collected data on birth outcomes at the infant's household. Supplemental data from other studies conducted at the same field site are presented to provide context. 95% confidence intervals were constructed around monthly estimates to examine statistical significance of findings.
  
  
  RESULTS
  Month of birth was associated with higher risk for adverse outcomes (neonatal mortality, low birthweight, preterm, and small for gestational age), even when controlling for maternal characteristics. Infants had 87% (95% CI: 27 - 176%) increased risk of neonatal mortality when born in August, the high point, versus March, the low point.
  
  
  CONCLUSIONS
  Seasonality of neonatal deaths, stillbirths, birth weight, gestational age, and small for gestational age were found in Nepal. Maternal factors, meteorological conditions, infectious diseases, and nutritional status may be associated with these adverse birth outcomes. Further research is needed to understand the causal mechanisms that explain the seasonality of adverse birth outcomes.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Hughes
authors.affiliation: Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, Maryland 21205, USA. jkatz1@jhu.edu.
authors.forename: Joanne
authors.initials: J
authors.lastname: Katz
authors.forename: Luke C
authors.initials: LC
authors.lastname: Mullany
authors.forename: Subarna K
authors.initials: SK
authors.lastname: Khatry
authors.forename: Steven C
authors.initials: SC
authors.lastname: LeClerq
authors.forename: Gary L
authors.initials: GL
authors.lastname: Darmstadt
authors.forename: James M
authors.initials: JM
authors.lastname: Tielsch
mesh_terms: D001724:Birth Weight; D005260:Female; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D009390:Nepal / Q000453:epidemiology; D047928:Premature Birth / Q000453:epidemiology*; D011446:Prospective Studies; D012424:Rural Population / Q000706:statistics & numerical data; D012621:Seasons; D050497:Stillbirth / Q000453:epidemiology*