title: Risk factors for small-for-gestational-age and preterm births among 19,269 Tanzanian newborns.
abstract: Few studies have differentiated risk factors for term-small for gestational age (SGA), preterm-appropriate for gestational age (AGA), and preterm-SGA, despite evidence of varying risk of child mortality and poor developmental outcomes.
  
  
  
  We analyzed birth outcome data from singleton infants, who were enrolled in a large randomized, double-blind, placebo-controlled trial of neonatal vitamin A supplementation conducted in Tanzania. SGA was defined as birth weight <10th percentile for gestation age and sex using INTERGROWTH standards and preterm birth as delivery at <37 complete weeks of gestation. Risk factors for term-SGA, preterm-AGA, and preterm-SGA were examined independently using log-binomial regression.
  
  
  
  Among 19,269 singleton Tanzanian newborns included in this analysis, 68.3 % were term-AGA, 15.8 % term-SGA, 15.5 % preterm-AGA, and 0.3 % preterm-SGA. In multivariate analyses, significant risk factors for term-SGA included maternal age <20 years, starting antenatal care (ANC) in the 3(rd) trimester, short maternal stature, being firstborn, and male sex (all p < 0.05). Independent risk factors for preterm-AGA were maternal age <25 years, short maternal stature, firstborns, and decreased wealth (all p < 0.05). In addition, receiving ANC services in the 1(st) trimester significantly reduced the risk of preterm-AGA (p = 0.01). Significant risk factors for preterm-SGA included maternal age >30 years, being firstborn, and short maternal stature which appeared to carry a particularly strong risk (all p < 0.05).
  
  
  
  Over 30 % of newborns in this large urban and rural cohort of Tanzanian newborns were born preterm and/or SGA. Interventions to promote early attendance to ANC services, reduce unintended young pregnancies, increased maternal height, and reduce poverty may significantly decrease the burden of SGA and preterm birth in sub-Saharan Africa.
  
  
  
  Australian New Zealand Clinical Trials Registry (ANZCTR) - ACTRN12610000636055 , registered on 3(rd) August 2010.
authors.affiliation: Ifakara Health Institute, Kiko Avenue, Mikocheni, Dar es Salaam, Tanzania. selukundo@gmail.com.|Africa Academy for Public Health, CM Plaza Building, Mwai Kibaki Road, Mikocheni, P.O.Box 79810, Dar es Salaam, Tanzania. selukundo@gmail.com.
authors.forename: Alfa
authors.initials: A
authors.lastname: Muhihi
authors.affiliation: Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Sudfeld
authors.affiliation: Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, USA.
authors.forename: Emily R
authors.initials: ER
authors.lastname: Smith
authors.affiliation: Africa Academy for Public Health, CM Plaza Building, Mwai Kibaki Road, Mikocheni, P.O.Box 79810, Dar es Salaam, Tanzania.|Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, USA.
authors.forename: Ramadhani A
authors.initials: RA
authors.lastname: Noor
authors.affiliation: Africa Academy for Public Health, CM Plaza Building, Mwai Kibaki Road, Mikocheni, P.O.Box 79810, Dar es Salaam, Tanzania.
authors.forename: Salum
authors.initials: S
authors.lastname: Mshamu
authors.affiliation: Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Briegleb
authors.affiliation: Africa Academy for Public Health, CM Plaza Building, Mwai Kibaki Road, Mikocheni, P.O.Box 79810, Dar es Salaam, Tanzania.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bakari
authors.affiliation: Ifakara Health Institute, Kiko Avenue, Mikocheni, Dar es Salaam, Tanzania.
authors.forename: Honorati
authors.initials: H
authors.lastname: Masanja
authors.affiliation: Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, USA.|Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, USA.|Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, USA.
authors.forename: Wafaie
authors.initials: W
authors.lastname: Fawzi
authors.affiliation: Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, USA.|Department of Medicine, Boston Children's Hospital, Boston, USA.
authors.forename: Grace Jean-Yee
authors.initials: GJ
authors.lastname: Chan
mesh_terms: D000328:Adult; D001724:Birth Weight; D001827:Body Height; D004311:Double-Blind Method; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D008423:Maternal Age; D015999:Multivariate Analysis; D011247:Pregnancy; D047928:Premature Birth / Q000209:etiology* / Q000517:prevention & control; D012044:Regression Analysis; D012307:Risk Factors; D012959:Socioeconomic Factors; D013636:Tanzania; D047929:Term Birth; D014801:Vitamin A / Q000627:therapeutic use; D014815:Vitamins / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D014815:Vitamins; D014801:Vitamin A
keywords: Birth weight; Preterm-AGA; Preterm-SGA; Risk factors; Tanzania; Term-SGA