title: Impact of maternal respiratory infections on low birth weight - a community based longitudinal study in an urban setting in Pakistan.
abstract: The health of mothers and their newborns is intricately related. The weight of the infant at birth is a powerful predictor of infant growth and survival, and is considered to be partly dependent on maternal health and nutrition during pregnancy. We conducted a longitudinal study in an urban community within Karachi to determine maternal predictors of newborn birth weight.
  
  
  
  Four hundred pregnant women were enrolled in the study during the period 2011-2013. Data related to symptoms of acute respiratory illness (fever, cough, difficulty breathing, runny nose, sore throat, headache, chills, and myalgia/lethargy) in the pregnant women were collected weekly until delivery. Birth weight of the newborn was recorded within 14 days of delivery and the weight of <2.5 kg was classified as low birth weight (LBW).
  
  
  
  A total of 9,853 symptom episodes were recorded of fever, cough, difficulty breathing, runny nose, sore throat, headache, chills, myalgias/lethargy in the enrolled pregnant women during the study. Out of 243 pregnant women whose newborns were weighed within 14 days of birth, LBW proportion was 21% (n = 53). On multivariate analysis, independent significant risk factors noted for delivering LBW babies were early pregnancy weight of < 57.5 kg [odds ratio adjusted (ORadj) = 5.1, 95% CI: (1.3, 19.9)] and gestational age [ORadj= 0.3, 95% CI (0.2, 0.7) for every one week increase in gestational age]. Among mothers with high socioeconomic status (SES), every 50-unit increase in the number of episodes of respiratory illness/100 weeks of pregnancy had a trend of association with an increased risk of delivering LBW infants [ORadj= 1.7, 95% CI: (1.0, 3.1)]. However, among mothers belonging to low SES, there was no association of the number of episodes of maternal respiratory illness during pregnancy with infants having LBW [ORadj= 0.9, 95% CI: (0.5, 3.5)].
  
  
  
  While overall respiratory illnesses during pregnancy did not impact newborn weight in our study, we found this trend in the sub-group of mothers belonging to the higher SES. Whether this is because in mothers belonging to lower SES, the effects of respiratory illnesses were overshadowed by other risk factors associated with poverty need to be further studied.
authors.affiliation: Department of Pediatrics and Child Health, The Aga Khan University, Karachi, 74800, Pakistan. Asad.ali@aku.edu.
authors.forename: Asad
authors.identifier: 0000-0001-5274-7665
authors.initials: A
authors.lastname: Ali
authors.affiliation: Department of Pediatrics and Child Health, The Aga Khan University, Karachi, 74800, Pakistan.
authors.forename: Umber
authors.initials: U
authors.lastname: Zaman
authors.affiliation: Department of Pediatrics and Child Health, The Aga Khan University, Karachi, 74800, Pakistan.
authors.forename: Sadia
authors.initials: S
authors.lastname: Mahmud
authors.affiliation: Department of Pediatrics and Child Health, The Aga Khan University, Karachi, 74800, Pakistan.
authors.forename: Gul-E-Shehwar
authors.initials: GE
authors.lastname: Zahid
authors.affiliation: Department of Pediatrics and Child Health, The Aga Khan University, Karachi, 74800, Pakistan.
authors.forename: Momin
authors.initials: M
authors.lastname: Kazi
authors.affiliation: Division of Infectious Diseases, University of Virginia School of Medicine Carter-Harrison Building, Room 1704, 345 Crispell Drive, Charlottesville, VA, 22908, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: Petri
authors.affiliation: Department of Pediatrics and Child Health, The Aga Khan University, Karachi, 74800, Pakistan.
authors.forename: Zulfiqar
authors.initials: Z
authors.lastname: Bhutta
authors.affiliation: Department of Pediatrics and Child Health, The Aga Khan University, Karachi, 74800, Pakistan.
authors.forename: Anita
authors.initials: A
authors.lastname: Zaidi
authors.affiliation: Division of Infectious Diseases, University of Virginia School of Medicine Carter-Harrison Building, Room 1704, 345 Crispell Drive, Charlottesville, VA, 22908, USA.
authors.forename: Molly A
authors.initials: MA
authors.lastname: Hughes
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008137:Longitudinal Studies; D016017:Odds Ratio; D010154:Pakistan; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000209:etiology / Q000503:physiopathology*; D011297:Prenatal Exposure Delayed Effects / Q000209:etiology / Q000503:physiopathology*; D012141:Respiratory Tract Infections / Q000150:complications / Q000503:physiopathology*; D012307:Risk Factors; D012923:Social Class; D014505:Urban Population / Q000706:statistics & numerical data*
keywords: ARI; Longitudinal observational study; Newborn weight; Pregnancy; Respiratory illness