Passive smoking increased risk of gestational diabetes mellitus independently and synergistically with prepregnancy obesity in Tianjin, China.
Passive smoking increased type 2 diabetes mellitus risk, but it is uncertain whether it also increased gestational diabetes mellitus (GDM) risk. We aimed to examine the association of passive smoking during pregnancy and its interaction with maternal obesity for GDM.



From 2010 to 2012, 12 786 Chinese women underwent a 50-g 1-hour glucose challenge test at 24 to 28 weeks of gestation and further underwent a 75-g 2-hour oral glucose tolerance test if the glucose challenge test result was ≥7.8 mmol/L. GDM was defined by the International Association of Diabetes and Pregnancy Study Group's cut points. Self-reported passive smoking during pregnancy was collected by a questionnaire. Logistic regression was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs). Additive interaction between maternal obesity and passive smoking was estimated using relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (S). Significant RERI > 0, AP > 0, or S > 1 indicated additive interaction.



A total of 8331 women (65.2%) were exposed to passive smoking during pregnancy. More women exposed to passive smoking developed GDM than nonexposed women (7.8% versus 6.3%, P = 0.002) with an adjusted OR of 1.29 (95%CI, 1.11 to 1.50). Compared with nonobesity and nonpassive smoking, prepregnancy obesity and passive smoking was associated with GDM risk with an adjusted OR of 3.09 (95%CI, 2.38-4.02) with significant additive interaction (P < .05 for RERI and AP).



Passive smoking during pregnancy increased GDM risk in Chinese women independently and synergistically with prepregnancy obesity.
Department of Epidemiology and Biostatistics, School of Public Health, Tianjin Medical University, Tianjin, China.|Tianjin Women and Children's Health Centre, Tianjin, China.
Junhong
J
Leng
Tianjin Women and Children's Health Centre, Tianjin, China.
Peng
P
Wang
Tianjin Women and Children's Health Centre, Tianjin, China.
Ping
P
Shao
Tianjin Women and Children's Health Centre, Tianjin, China.
Cuiping
C
Zhang
Tianjin Women and Children's Health Centre, Tianjin, China.
Weiqin
W
Li
Tianjin Women and Children's Health Centre, Tianjin, China.
Nan
N
Li
Tianjin Women and Children's Health Centre, Tianjin, China.
Leishen
L
Wang
Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hong Kong, SAR, China.
Hairong
H
Nan
Population Cancer Research Program and Department of Pediatrics, Dalhousie University, Halifax, Canada.
Zhijie
Z
Yu
Chronic Disease Epidemiology Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA, USA.
Gang
G
Hu
Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity and The Chinese University of Hong Kong-Prince of Wales Hospital-International Diabetes Federation Centre of Education, Hong Kong, SAR, China.
Juliana C N
JC
Chan
Department of Epidemiology and Biostatistics, School of Public Health, Tianjin Medical University, Tianjin, China.
Xilin
X
Yang
D000328:Adult; D001724:Birth Weight; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D016640:Diabetes, Gestational / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D005951:Glucose Tolerance Test; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000150:complications*; D011247:Pregnancy; D011379:Prognosis; D012307:Risk Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D055815:Young Adult
D014028:Tobacco Smoke Pollution
Chinese; gestational diabetes mellitus; obesity; passive smoking