Prospective Cohort Study of Thai Children

SECONDHAND SMOKING IN PREGNANT WOMEN

AND TIME OF THE FIRST TOOTH ERUPTION

DIEN HOA ANH VUPhD Student – Faculty of Dentistry

Khon Kaen University

CONTENT

• INTRODUCTION

• OBJECTIVE

•METHODS

• RESULTS

• DISCUSSION

• CONCLUSION

04/21/23 2

ABBREVIATION

• BW Birth Weight

• DTE Delayed first Tooth Eruption

• PCTC Prospective Cohort study of Thai Children

• SHS Secondhand Smoking

04/21/23 3

INTRODUCTION

• DTE: problems / dental development

• hold space

• align into correct position

• chew and speak

• Influence factors

04/21/23 4

INTRODUCTION

• Secondhand smoking (SHS)

• Negative effect

• Common in Thai males

• High prevalence (29.8%) of SHS

04/21/23 5

OBJECTIVE

04/21/23 6

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, 2002

04/21/23 7

• Inclusion criteria:

• accessible year-round

• 800 to 900 newborns on average each year

• intend to live 5 years

• long-term commitment with the project

04/21/23 8

METHODS – Study Design

• Family members

• In-person interview, diary records, medical records

• Secondary data – community and demographic variables

04/21/23 9

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

04/21/23 10

METHODS – Study Design

Independent variables

•SHS during pregnancy: Yes/No•Number of cigarettes: • 0• 0 < CIG < 50th percentile• 50th percentile +

Outcomes

•DTE: Yes/No

•Time to eruption of the first tooth

04/21/23 11

METHODS – Independent variables and outcomes

METHODS – Potential bias

• Parents’ education level

•Mother’s age

• Child’s gender

• Birth weight

04/21/23 12

METHODS – Statistical Analysis

• Description analysis

• Pearson regression

• Cox proportional regression

• Generalized estimating equation

• Stata SE 12.0

• p-value < .05

04/21/23 13

RESULTS – Study sites

04/21/23 14

Figure 1. Number of study members and location of PCTC sites in Thailand

RESULTS – Demographic Characteristics

Characteristics Total Sites

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 genderBirth weight

04/21/23 15

Table 1. Demographic characteristics in five study sites

RESULTS

Table 2. Odds ratio of having DTE among five study sites04/21/23 16

Area Number % DTE Crude OR 95%CI p-value

North xxx xx.x 1.00 Reference 0.xxx

Northeast xxx xx.x x.xx x.xx – x.xx

Central xxx xx.x x.xx x.xx – x.xx

South xxx xx.x x.xx x.xx – x.xx

Bangkok xxx xx.x x.xx x.xx – x.xx

RESULTS

n % Crude HR (95% CI) Adjusted HR* (95% CI)

Non-SHS xxxx xx.xx 1 Reference 1 Reference

SHS < 50th percentile xxxx xx.xx x.xx x.xx – x.xx x.xx x.xx – x.xx

SHS ≥ 50th percentile xxxxx xx.xx x.xx x.xx – x.xx x.xx x.xx – x.xx

04/21/23 17

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

04/21/23 18

RESULTS

Figure 3. Difference in the probability of DTE between SHS group and non-SHS group

04/21/23 19

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.

04/21/23 20

DISCUSSION – Strength

• Strongest observational design

•Multiple risk factors

• Large birth cohort study

• National representative

•Minimal loss to follow-up

04/21/23 21

DISCUSSION – Limitation

• Information bias – trained and calibrated the interviewers

• Potential confounding factors – adjusting

• Causal inferences – suspect

• Change of association over time?

04/21/23 22

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

04/21/23 23

04/21/23 24

REFERENCES