title: Pre-pregnancy body mass index in relation to infant birth weight and offspring overweight/obesity: a systematic review and meta-analysis.
abstract: BACKGROUND
  Overweight/obesity in women of childbearing age is a serious public-health problem. In China, the incidence of maternal overweight/obesity has been increasing. However, there is not a meta-analysis to determine if pre-pregnancy body mass index (BMI) is related to infant birth weight (BW) and offspring overweight/obesity.
  
  
  METHODS
  Three electronic bibliographic databases (MEDLINE, EMBASE and CINAHL) were searched systematically from January 1970 to November 2012. The dichotomous data on pre-pregnancy overweight/obesity and BW or offspring overweight/obesity were extracted. Summary statistics (odds ratios, ORs) were used by Review Manager, version 5.1.7.
  
  
  RESULTS
  After screening 665 citations from three electronic databases, we included 45 studies (most of high or medium quality). Compared with normal-weight mothers, pre-pregnancy underweight increased the risk of small for gestational age (SGA) (odds ratios [OR], 1.81; 95% confidence interval [CI], 1.76-1.87); low BW (OR, 1.47; 95% CI, 1.27-1.71). Pre-pregnancy overweight/obesity increased the risk of being large for gestational age (LGA) (OR, 1.53; 95% CI, 1.44-1.63; and OR, 2.08; 95% CI; 1.95-2.23), high BW (OR, 1.53; 95% CI, 1.44-1.63; and OR, 2.00; 95% CI; 1.84-2.18), macrosomia (OR, 1.67; 95% CI, 1.42-1.97; and OR, 3.23; 95% CI, 2.39-4.37), and subsequent offspring overweight/obesity (OR, 1.95; 95% CI, 1.77-2.13; and OR, 3.06; 95% CI, 2.68-3.49), respectively. Sensitivity analyses revealed that sample size, study method, quality grade of study, source of pre-pregnancy BMI or BW had a strong impact on the association between pre-pregnancy obesity and LGA. No significant evidence of publication bias was observed.
  
  
  CONCLUSIONS
  Pre-pregnancy underweight increases the risk of SGA and LBW; pre-pregnancy overweight/obesity increases the risk of LGA, HBW, macrosomia, and subsequent offspring overweight/obesity. A potential effect modification by maternal age, ethnicity, gestational weight gain, as well as the role of gestational diseases should be addressed in future studies.
authors.affiliation: State Key Laboratory of Reproductive Medicine, Department of Pediatrics, Nanjing Maternity and Child Health Care Hospital, Nanjing Medical University, Nanjing, China.
authors.forename: Zhangbin
authors.initials: Z
authors.lastname: Yu
authors.forename: Shuping
authors.initials: S
authors.lastname: Han
authors.forename: Jingai
authors.initials: J
authors.lastname: Zhu
authors.forename: Xiaofan
authors.initials: X
authors.lastname: Sun
authors.forename: Chenbo
authors.initials: C
authors.lastname: Ji
authors.forename: Xirong
authors.initials: X
authors.lastname: Guo
mesh_terms: D001724:Birth Weight / Q000502:physiology*; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D009765:Obesity / Q000453:epidemiology*; D050177:Overweight / Q000453:epidemiology*; D011247:Pregnancy