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

CONTENT INTRODUCTION OBJECTIVE METHODS RESULTS DISCUSSION CONCLUSION 6/4/20162

ABBREVIATION BWBirth Weight DTE Delayed first Tooth Eruption PCTCProspective Cohort study of Thai Children SHSSecondhand Smoking 6/4/20163

INTRODUCTION DTE: problems / dental development hold space align into correct position chew and speak Influence factors 6/4/20164

INTRODUCTION Secondhand smoking (SHS) Negative effect Common in Thai males High prevalence (29.8%) of SHS 6/4/20165

OBJECTIVE 6/4/20166 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: 4,300 infants, 5 sites in Thailand October 15, 2000 and September 14, /4/20167

Inclusion criteria: accessible year-round 800 to 900 newborns on average each year intend to live 5 years long-term commitment with the project 6/4/20168 METHODS – Study Design

Family members In-person interview, diary records, medical records Secondary data – community and demographic variables 6/4/20169 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 6/4/ METHODS – Study Design

Independent variables SHS during pregnancy: Yes/No Number of cigarettes: 0 0 < CIG < 50 th percentile 50 th percentile + Outcomes DTE: Yes/No Time to eruption of the first tooth 6/4/ METHODS – Independent variables and outcomes

METHODS – Potential bias Parents’ education level Mother’s age Child’s gender Birth weight 6/4/201612

METHODS – Statistical Analysis Description analysis Pearson regression Cox proportional regression Generalized estimating equation Stata SE 12.0 p-value <.05 6/4/201613

RESULTS – Study sites 6/4/ Figure 1. Number of study members and location of PCTC sites in Thailand

RESULTS – Demographic Characteristics CharacteristicsTotalSites North (n=xxx) Northeast (n=xxx) Central (n=xxx) South (n=xxx) Bangkok (n=xxx) Mother’s age (years) Mother’s highest education Father’s age (years) Father’s highest education Child’s gender Birth weight 6/4/ Table 1. Demographic characteristics in five study sites

RESULTS Table 2. Odds ratio of having DTE among five study sites 6/4/ AreaNumber% DTECrude OR95%CIp-value Northxxxxx.x1.00Reference0.xxx Northeastxxxxx.xx.xxx.xx – x.xx Centralxxxxx.xx.xxx.xx – x.xx Southxxxxx.xx.xxx.xx – x.xx Bangkokxxxxx.xx.xxx.xx – x.xx

RESULTS n%Crude HR (95% CI)Adjusted HR* (95% CI) Non-SHSxxxxxx.xx1Reference1 SHS < 50 th percentilexxxxxx.xxx.xxx.xx – x.xxx.xxx.xx – x.xx SHS ≥ 50 th percentilexxxxxxx.xxx.xxx.xx – x.xxx.xxx.xx – x.xx 6/4/ Table 3. Crude and adjusted hazard ratio of DTE between levels of smoking groups and non-smoking group * Hazard ratio adjusted for child’s gender, maternal age, parents’ highest education level, birth weight, and alcohol drinking and caffeine consumption during pregnancy

RESULTS Figure 2. Positive association between the number of cigarettes smoked by the fathers and the time of first tooth eruption 6/4/201618

RESULTS Figure 3. Difference in the probability of DTE between SHS group and non-SHS group 6/4/201619

DISCUSSION 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. 6/4/201620

DISCUSSION – Strength Strongest observational design Multiple risk factors Large birth cohort study National representative Minimal loss to follow-up 6/4/201621

DISCUSSION – Limitation Information bias – trained and calibrated the interviewers Potential confounding factors – adjusting Causal inferences – suspect Change of association over time? 6/4/201622

CONCLUSION SHS in Thai pregnant women was associated with delayed time of the first tooth eruption in infants up Many problems in the dental and nutritional development of infants Further studies 6/4/201623

6/4/ REFERENCES