title: Body mass index at age 18-20 and later risk of spontaneous abortion in the Health Examinees Study (HEXA).
abstract: BACKGROUND
  Spontaneous abortion (SA) affects 11.2% of recognized pregnancies in Korea. Many studies have focused on the increased risk of SA in obese populations, but there are few studies that have focused on underweight (Body mass index (BMI) <18.5 kg/m2) women, especially in relation to pre-pregnancy BMI. The aim of this study was to examine the role of pre-pregnancy BMI at age 18-20 in later SA.
  
  
  METHODS
  Among the women who were ever pregnant in the Health Examinees Study (HEXA), which was one of the cohorts studied in the KoGES (Korean Genome and Epidemiology Study) from 2004 to 2012 (N = 80,447), the likelihood of SA based on pre-pregnancy BMI, classified by the criteria for Asians (Underweight: <18.5 kg/m2; Normal range: 18.5-22.9 kg/m2; Overweight at risk: 23-24.9 kg/m2; Obese I: 25-29.9 kg/m2; Obese II: ≥30 kg/m2), was presented as odds ratios (ORs) and 95% confidence intervals (95% CIs) using logistic regression models.
  
  
  RESULTS
  Being underweight or obese relative to the normal weight range was associated with a higher likelihood of SA (OR = 1.10 [95% CI = 1.05-1.15] in underweight women and OR = 1.06 [95% CI = 0.96-1.16] in obese women), and this effect was much greater in women who experienced recurrent SAs (for three or more SAs: OR = 1.29 [95% CI 1.14-1.46] in underweight women and OR = 1.39 [95% CI 1.09-1.78] in obese women). Obesity was associated with an increased likelihood of SA at a younger age (≤25 years), whereas underweight was associated with an increased OR of SA at an older age (≥26 years).
  
  
  CONCLUSIONS
  As this study was conducted with baseline data of original cohort which focused on other chronic diseases, recall for previous pregnancy-related information might be less accurate. However, this study shows strength in its large size and prospective potential.
  
  
  CONCLUSIONS
  Pre-pregnancy BMI at ages 18-20 years revealed a U-shaped association with SA, and underweight and obese women showed increased likelihood for SA during different age periods.
authors.affiliation: Department of Biomedical Science, Seoul National University College of Medicine, Seoul, South Korea. sunjae@snu.ac.kr.
authors.forename: Sun Jae
authors.initials: SJ
authors.lastname: Jung
authors.affiliation: Department of Biomedical Science, Seoul National University College of Medicine, Seoul, South Korea. suepark@snu.ac.kr.|Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, South Korea. suepark@snu.ac.kr.|Cancer Research Institute, Seoul National University Hospital, Seoul, South Korea. suepark@snu.ac.kr.
authors.forename: Sue Kyung
authors.initials: SK
authors.lastname: Park
authors.affiliation: Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, South Korea. shinaesun@snu.ac.kr.
authors.forename: Aesun
authors.initials: A
authors.lastname: Shin
authors.affiliation: Department of Preventive Medicine, Kangwon National University, Seoul, South Korea. sangahlee@kangwon.ac.kr.
authors.forename: Sang-Ah
authors.initials: SA
authors.lastname: Lee
authors.affiliation: Department of Biomedical Science, Seoul National University College of Medicine, Seoul, South Korea. jiyeob.choi@gmail.com.
authors.forename: Ji-Yeob
authors.initials: JY
authors.lastname: Choi
authors.affiliation: Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, South Korea. ychong1@snu.ac.kr.
authors.forename: Yun-Chul
authors.initials: YC
authors.lastname: Hong
authors.affiliation: Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, South Korea. kyyoo@snu.ac.kr.
authors.forename: Keun-Young
authors.initials: KY
authors.lastname: Yoo
authors.affiliation: Department of Family Medicine, Seoul National University Hospital, Seoul, South Korea. docmohw@snu.ac.kr.
authors.forename: Jong-Koo
authors.initials: JK
authors.lastname: Lee
authors.affiliation: Department of Biomedical Science, Seoul National University College of Medicine, Seoul, South Korea. dhkang@snu.ac.kr.|Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, South Korea. dhkang@snu.ac.kr.|Cancer Research Institute, Seoul National University Hospital, Seoul, South Korea. dhkang@snu.ac.kr.
authors.forename: Daehee
authors.initials: D
authors.lastname: Kang
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology / Q000209:etiology*; D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D016017:Odds Ratio; D050177:Overweight / Q000150:complications*; D011247:Pregnancy; D060728:Reproductive Health; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D013851:Thinness / Q000150:complications*; D055815:Young Adult