Int J Med Sci 2020; 17(13):2002-2012. doi:10.7150/ijms.47076

Research Paper

Comparison of three classification systems of Prepregnancy Body Mass Index with Perinatal Outcomes in Japanese Obese Pregnant Women: A retrospective study at a single center

Ryo Sugimura1, Yukiko Kohmura-Kobayashi1✉, Megumi Narumi1, Naomi Furuta-Isomura1, Tomoaki Oda1, Naoaki Tamura1, Toshiyuki Uchida1, Kazunao Suzuki1, Motoi Sugimura2, Naohiro Kanayama1, Hiroaki Itoh1

1. Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.
2. Department of Obstetrics, Gynecology and Family Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.

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Citation:
Sugimura R, Kohmura-Kobayashi Y, Narumi M, Furuta-Isomura N, Oda T, Tamura N, Uchida T, Suzuki K, Sugimura M, Kanayama N, Itoh H. Comparison of three classification systems of Prepregnancy Body Mass Index with Perinatal Outcomes in Japanese Obese Pregnant Women: A retrospective study at a single center. Int J Med Sci 2020; 17(13):2002-2012. doi:10.7150/ijms.47076. Available from http://www.medsci.org/v17p2002.htm

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Abstract

In Japan, pregnant women are diagnosed as obese if the prepregnancy body mass index (BMI) is ≥25 kg/m2. However, this is different from other countries. The Institute of Medicine (IOM) classifies prepregnancy BMI as underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25.0-29.9 kg/m2), and obese (BMI ≥30 kg/m2). In addition to these four categories, the American College of Obstetricians and Gynecologists (ACOG) classifies prepregnancy BMI as obesity class I (BMI 30.0-34.9 kg/m2), obesity class II (BMI 35.0-39.9 kg/m2), and obesity class III (BMI ≥40 kg/m2). We conducted a retrospective cohort study to compare obstetric outcomes by the three different categorizations in 6,066 pregnant women who gave birth between 2010 and 2019. According to Japanese classification, 668 (11%) pregnant women were classified as obese, and significant odds ratios (OR) were observed for hypertensive disorders of pregnancy (HDP; 3.32), gestational diabetes mellitus (GDM; 3.39), large for gestational age (LGA; 2.91), and macrosomia (4.01). According to the classification of IOM, 474 (7.8%) and 194 (3.1%) were classified as overweight and obese pregnant women, respectively. Specifically, a high OR was observed in obese pregnant women for HDP (5.85) and GDM (5.0). ACOG classification categorized 474 (7.8%) pregnant women as overweight, 141 (2.3%) as obesity class I, 41 (0.6%) as obesity class II, and 12 (0.2%) as obesity class III. In obesity class III, a significantly high OR was observed for HDP (12.89), GDM (8.37), and LGA (5.74). The Japanese classification may be useful for low-risk pregnancies, whereas IOM classification may be applicable to identify high-risk pregnancies. ACOG criteria may be useful for step-wise assessments of HDP and GDM risks in Japanese pregnant women; however, the number of class II and III obese pregnant women was small.

Keywords: prepregnancy, BMI, obese, classification, perinatal outcomes