Case-control study of nutritional and environmental factors and the risk of oral clefts in Thailand.
BACKGROUND
One infant in 700 is born with an oral cleft. Prior studies suggest low micronutrient status is associated with an increased risk of oral clefts. Environmental factors such as passive smoke exposure or supplement use may also affect oral cleft risk. We examined nutrition and environmental related risk factors for oral clefts.


METHODS
We conducted a case-control study in Northeast Thailand in 2012 to 2013. We enrolled 95 cases and 95 controls. We recruited cases with a nonsyndromic cleft lip with or without a cleft palate (CL±P) less than 24 months old. Cases were matched to controls on age and place of conception. We collected survey data, a food frequency questionnaire, and measured zinc concentrations in toenail trimmings. We calculated descriptive statistics by case and control status. We used conditional logistic regression to estimate unadjusted and adjusted associations, 95% confidence intervals (CIs), and p-values.


RESULTS
Any liver intake (adjusted OR [aOR] for ≥1/week versus none), 10.58; 95%CI, 1.74-64.37, overall p = 0.02) and the presence of food insecurity (aOR, 9.62; 95% CI, 1.52-61.05; p = 0.02) in the periconceptional period increased CL±P risk. Passive smoke exposure increased the risk of CL±P (aOR, 6.52; 95% CI, 1.98-21.44; p < 0.01). Toenail zinc concentrations were not associated with CL±P risk.


CONCLUSIONS
Our findings add to a growing body of knowledge of environmental risk factors for oral clefts from low- and middle-income countries. Our findings on liver are contradictory to prior results. Large multisite studies are needed to identify environmental and genetic risk factors for oral clefts. Birth Defects Research (Part A) 106:624-632, 2016. © 2016 Wiley Periodicals, Inc.
Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, Washington.
Christy M
CM
McKinney
Department of Community Dentistry, Faculty of Dentistry, Khon Kaen University, Thailand.
Araya
A
Pisek
Division of Plastic Surgery, Faculty of Medicine, Khon Kaen University, Thailand.
Bowornsilp
B
Chowchuen
Departments of Oral Health Sciences, Biostatistics, and Global Health, Schools of Dentistry and Public Health, USA.
Timothy
T
DeRouen
Department of Nutrition, Faculty of Public Health, Khon Kaen University, Thailand.
Benja
B
Muktabhant
Nursing Division, Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Thailand.
Suteera
S
Pradubwong
Departments of Pharmacy and Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington.
Cathy
C
Yeung
Department of Community Dentistry, Faculty of Dentistry, and Chronic Inflammatory and Systemic Diseases Associated with Oral Health Research Group, Khon Kaen University, Thailand.
Waranuch
W
Pitiphat
D016022:Case-Control Studies; D002971:Cleft Lip / Q000453:epidemiology / Q000209:etiology; D002972:Cleft Palate / Q000453:epidemiology / Q000209:etiology; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D018977:Micronutrients / Q000172:deficiency*; D012307:Risk Factors; D013785:Thailand / Q000453:epidemiology
D018977:Micronutrients
Thailand; cleft lip; cleft palate; epidemiology; liver; oral cleft; passive smoking; zinc