Prospective Cohort Study of Thai Children SECONDHAND SMOKING IN PREGNANT WOMEN AND TIME OF THE FIRST TOOTH ERUPTION DIEN HOA ANH VU PhD Student – Faculty of Dentistry Khon Kaen University

CONTENTS INTRODUCTION OBJECTIVE METHODS RESULTS DISCUSSION CONCLUSION 10/12/20152

ABBREVIATION BWBirth Weight DTE Delayed first Tooth Eruption GAGestational Age PCTCProspective Cohort study of Thai Children SHSSecondhand Smoking 10/12/20153

INTRODUCTION DTE: problems / dental development hold space align into correct position chew and speak Influence factors 10/12/20154

INTRODUCTION Secondhand smoking (SHS) Negative effect Common in Thai males High prevalence (29.8%) of SHS 10/12/20155

OBJECTIVE 10/12/20156 To determine whether SHS during pregnancy period delayed the time of first tooth eruption in Thai infants

METHODS – Study Design Part of PCTC Large birth cohort study: > 4,000 infants, 5 sites in Thailand October 15, 2000 and September 14, /12/20157

METHODS – Study Design Inclusion criteria: accessible year-round 800 to 900 newborns on average each year intend to live 5 years long-term commitment with the project 10/12/20158

METHODS – Study Design Informed consent The National Ethics Committee of the Ministry of Public Health of Thailand Khon Kaen University Ethics Committee for Human Research 10/12/20159

METHODS – Independent variables and outcomes Family members In-person interview, diary records, medical records Secondary data – community and demographic variables 10/12/201510

METHODS – Independent variables and outcomes Independent variables SHS during pregnancy: Yes/No Number of cigarettes Outcomes DTE: Yes/No Time to eruption of the first tooth 10/12/201511

METHODS – Potential bias Mother’s age, education level Income Alcohol consumption Child’s gender BW GA Study site 10/12/201512

METHODS – Statistical Analysis Description analysis Cox proportional regression Multiple logistic regression Generalized estimating equation (GEE) Stata SE 12.0 p-value <.05 10/12/201513

RESULTS – Study sites 10/12/ Figure 1. Number of study members and location of PCTC sites in Thailand

RESULTS – Demographic Characteristics CharacteristicsTotal (n)Sites (%) North (n=xxx) Northeast (n=xxx) Central (n=xxx) South (n=xxx) Bangkok (n=xxx) Mother’s age (mean ± SD) 27.1       5.9 Alcohol drinking Infant’s gender (females)2, Low BW Preterm birth /12/ Table 1. Demographic characteristics in five study sites

RESULTS Table 2. Percentage of SHS in pregnant women among five study sites 10/12/ Study siteNumber of SHS% of SHS North Northeast Central South Bangkok Total2,

RESULTS SHS statusCrude HR (95% CI)Adjusted HR* (95% CI) Non-SHS 1.00Reference1.00Reference SHS – – /12/ Table 3. Crude and adjusted HR of not having first tooth eruption *HR adjusted for child’s gender, maternal age, parents’ highest education level, income, BW, GA, and alcohol drinking during pregnancy, stratifying by study site.

FactorsCrude HR (95% CI)Adjusted HR* (95% CI) SHS Yes – 1.42 No 1.00 Gender Female – 0.78 Male 1.00 BW Normal BW – 0.74 Low BW 1.00 GA Normal – 0.96 Preterm birth /12/ Table 4. Crude and adjusted OR of DTE

RESULTS Figure 2. Difference in the probability of not having erupted tooth between SHS group and non-SHS group 10/12/201519

RESULTS Figure 2. Difference in the probability of not having erupted tooth between females and males 10/12/201520

DISCUSSION [to be added] The time of first tooth eruption was delayed in SHS women Biological plausible Consistent with other previous studies Similar with the study of Adler et al. Lawoyin et al. – Opposite relationship between BW and time of first tooth eruption. 10/12/201521

DISCUSSION – Strength Strongest observational design Multiple risk factors Large birth cohort study National representative Minimal loss to follow-up 10/12/201522

DISCUSSION – Limitation Information bias – trained and calibrated the interviewers Potential confounding factors – adjusting Causal inferences – suspect Change of association over time? 10/12/201523

CONCLUSION SHS in Thai pregnant women was associated with delayed time of the first tooth eruption in infants Many problems in the dental and nutritional development of infants Further studies 10/12/201524

REFERENCES 10/12/201525