title: Classification tree analysis of postal questionnaire data to identify risk of excessive gestational weight gain.
abstract: OBJECTIVE
  overweight/obese weight status during pregnancy increases risk of a range of adverse health outcomes for mother and child. Whereas identification of those who are overweight/obese pre-pregnancy and in early pregnancy is straightforward, prediction of who will experience excessive gestational weight gain (EGWG), and thus be at greater risk of becoming overweight or obese during pregnancy is more challenging. The present study sought to better identify those at risk of EGWG by exploring pre-pregnancy BMI as well as a range of psychosocial risk factors identified as risk factors in prior research.
  
  
  METHODS
  225 pregnant women completed self-reported via postal survey measures of height, weight, and psychosocial variables at 16-18 weeks gestation, and reported their weight again at 32-34 weeks to calculate GWG. Classification and regression tree analysis (CART) was used to find subgroups in the data with increased risk of EGWG based on their pre-pregnancy BMI and psychosocial risk factor scores at Time 1.
  
  
  RESULTS
  CART confirmed that self-reported BMI status was a strong predictor of EGWG risk for women who were overweight/obese pre-pregnancy. Normal weight women with low motivation to maintain a healthy diet and who reported lower levels of partner support were also at considerable risk of EGWG.
  
  
  CONCLUSIONS
  present findings offer support for inclusion of psychosocial measures (in addition to BMI) in early antenatal visits to detect risk of EGWG. However, these findings also underscore the need for further consideration of effect modifiers that place women at increased or decreased risk of EGWG. Proposed additional constructs are discussed to direct further theory-driven research.
authors.affiliation: School of Psychology, Deakin University, Australia. Electronic address: matthewf@deakin.edu.au.
authors.forename: Matthew
authors.initials: M
authors.lastname: Fuller-Tyszkiewicz
authors.affiliation: School of Psychology, Deakin University, Australia.
authors.forename: Helen
authors.initials: H
authors.lastname: Skouteris
authors.affiliation: School of Psychology, Deakin University, Australia.
authors.forename: Briony
authors.initials: B
authors.lastname: Hill
authors.affiliation: School of Public Health and Preventative Medicine, Monash University, Australia.
authors.forename: Helena
authors.initials: H
authors.lastname: Teede
authors.affiliation: School of Psychology, Deakin University, Australia.
authors.forename: Skye
authors.initials: S
authors.lastname: McPhie
mesh_terms: D000328:Adult; D001828:Body Image / Q000523:psychology*; D015992:Body Mass Index; D000072001:Diet, Healthy; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D009042:Motivation; D009765:Obesity / Q000523:psychology*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000523:psychology*; D037841:Pregnant People / Q000523:psychology; D011295:Prenatal Care / Q000523:psychology*; D012044:Regression Analysis; D012307:Risk Factors; D057566:Self Report; D011795:Surveys and Questionnaires; D015430:Weight Gain; D055815:Young Adult
keywords: BMI; Classification and regression tree analysis; Gestational weight gain; Pregnancy; Psychosocial risk factors