Georgia Ntani, Peter F Day, Janis Baird, Keith M Godfrey, Sian M Robinson, Cyrus Cooper, Hazel M Inskip 12 th June 2014 Maternal and early life factors associated with tooth emergence patterns and number of teeth at one and two years of age

Background: Primary dentition Why are we interested? Caries in primary (or baby) teeth is one of the most common health problems affecting young children Advanced tooth eruption may be associated with increased risk of dental caries What do we know? Genetic influences [1] Environmental influences, including weight and length at birth [2], maternal smoking [3] and malnutrition [4] [1] Hughes et al, J Dent Res 2007 [2] Bastos et al, Arch Oral Biol 2007 [3] Rantakallio et al, Growth 1983 [4] Psoter et al, Community Dent Oral Epidemiol 2008

Objective To examine the interrelationship of timing of first primary tooth emergence and number of teeth at ages one and two years with pre-conception, pregnancy and postnatal factors, using data from the Southampton Women’s Survey (SWS)

Southampton Women’s Survey (SWS) 12,583 non-pregnant Southampton women aged interviewed about diet, body composition, physical activity, social circumstances and lifestyle Subsequent pregnancies studied. 3,159 live singleton births - babies followed through infancy and beyond

Primary Dentition One year visit Age or date at which the child’s first tooth emerged Erupted teeth recorded on a dental chart Two year visit Erupted teeth recorded on a dental chart

Primary Dentition - Outcomes Age of first tooth eruption continuous Number of teeth at 1 year of age continuous Number of teeth at 2 years of age: 52% of the children had 16 teeth. Outcome dichotomised: children with > 16 teeth characterised as having advanced dental development

Potential risk factors Maternal social factors Education, receipt of benefits, Index of Multiple Deprivation Maternal characteristics Age at birth of the child, weight, body mass index (BMI), skinfold thickness, smoking during pregnancy, ethnicity, dietary quality score, and walking speed Children’s characteristics Sex, crown-heel length, weight and head circumference at birth, duration of breast feeding and weight and height at 1 and 2 years of age

Statistical analysis Age of first deciduous tooth and number of teeth at 1 year of age Stepwise multiple linear regression models Number of teeth at 2 years of age Stepwise multiple binomial regression models with robust standard errors Variable added in stepwise regression process if p-value<0.01

Results – Demographic characteristics Mean (SD) or N (%) N=2740 MATERNAL CHARACTERISTICS Age at birth of the child (yrs) 31 (4) Nulliparous (n (%)) 1404 (51%) Smoking during pregnancy (n (%)) 396 (15%) Receipt of benefits (before pregnancy) (n (%)) 395 (14%) Ethnic origin: White (n (%)) 2633 (96%) CHILDREN CHARACTERISTICS Gestational age (weeks) 40 (1) Birth weight (kg) 3.50 (0.47)

Results – Dentition data All Mean (SD) or % Age (weeks) of first tooth (reported at one year follow-up) 30 (9) Number of teeth (assessed at one year follow-up) 6 (3) Advanced dentally developed (assessed at two years follow-up) No (16 teeth or fewer) 66% Yes (More than 16 teeth) 34%

Results – Associations with risk factors Age of first tooth eruption (weeks) Number of teeth at one year Advanced dentally developed (>16 teeth) at two years MATERNAL FACTORS β (95% CI)P PRR 3 (95% CI)P In pregnancy smoking status (Yes v No)-2.2 (-3.2, -1.1)< (0.5, 1.2)< (1.0, 1.5)0.01 Maternal ethnic origin (Asian v White)2.7 (0.6, 4.7) (-1.7, -0.4) (0.3, 0.9)0.03 Pre-pregnancy adiposity (Subscapular skinfold (mm)) 1.1 (1.0, 1.2)0.004 Pre-pregnancy physical activity (Walking speed) (0.8, 1.0)0.004 Index of Multiple Deprivation (1.1, 1.3)0.002 EARLY LIFE FACTORS Gestational age (weeks)-0.7 (-1.0, -0.3)<0.001 Length at birth (cm)0.2 (0.2, 0.3)<0.001 Length growth in first year (SD)0.3 (0.2, 0.5)<0.001 Birth weight (kg)-2.7 (-3.6, -1.8)<0.001 BMI(kg/m 2 ) at one year (0.05, 0.2) (1.0, 1.1) Log-transformed 2 Estimates for walking speed are for trend across increasing levels 3 RR: Relative Risk

Results – Associations with risk factors Age of first tooth eruption (weeks) Number of teeth at one year Advanced dentally developed (>16 teeth) at two years MATERNAL FACTORS β (95% CI)P PRR 3 (95% CI)P In pregnancy smoking status (Yes v No)-2.2 (-3.2, -1.1)< (0.5, 1.2)< (1.0, 1.5)0.01 Maternal ethnic origin (Asian v White)2.7 (0.6, 4.7) (-1.7, -0.4) (0.3, 0.9)0.03 Pre-pregnancy adiposity (Subscapular skinfold (mm)) 1.1 (1.0, 1.2)0.004 Pre-pregnancy physical activity (Walking speed) (0.8, 1.0)0.004 Index of Multiple Deprivation (1.1, 1.3)0.002 EARLY LIFE FACTORS Gestational age (weeks)-0.7 (-1.0, -0.3)<0.001 Length at birth (cm)0.2 (0.2, 0.3)<0.001 Length growth in first year (SD)0.3 (0.2, 0.5)<0.001 Birth weight (kg)-2.7 (-3.6, -1.8)<0.001 BMI(kg/m 2 ) at one year (0.05, 0.2) (1.0, 1.1) Log-transformed 2 Estimates for walking speed are for trend across increasing levels 3 RR: Relative Risk

Results – Associations with risk factors Age of first tooth eruption (weeks) Number of teeth at one year Advanced dentally developed (>16 teeth) at two years MATERNAL FACTORS β (95% CI)P PRR 3 (95% CI)P In pregnancy smoking status (Yes v No)-2.2 (-3.2, -1.1)< (0.5, 1.2)< (1.0, 1.5)0.01 Maternal ethnic origin (Asian v White)2.7 (0.6, 4.7) (-1.7, -0.4) (0.3, 0.9)0.03 Pre-pregnancy adiposity (Subscapular skinfold (mm)) 1.1 (1.0, 1.2)0.004 Pre-pregnancy physical activity (Walking speed) (0.8, 1.0)0.004 Index of Multiple Deprivation (1.1, 1.3)0.002 EARLY LIFE FACTORS Gestational age (weeks)-0.7 (-1.0, -0.3)<0.001 Length at birth (cm)0.2 (0.2, 0.3)<0.001 Length growth in first year (SD)0.3 (0.2, 0.5)<0.001 Birth weight (kg)-2.7 (-3.6, -1.8)<0.001 BMI(kg/m 2 ) at one year (0.05, 0.2) (1.0, 1.1) Log-transformed 2 Estimates for walking speed are for trend across increasing levels 3 RR: Relative Risk

Results – Associations with risk factors Age of first tooth eruption (weeks) Number of teeth at one year Advanced dentally developed (>16 teeth) at two years MATERNAL FACTORS β (95% CI)P PRR 3 (95% CI)P In pregnancy smoking status (Yes v No)-2.2 (-3.2, -1.1)< (0.5, 1.2)< (1.0, 1.5)0.01 Maternal ethnic origin (Asian v White)2.7 (0.6, 4.7) (-1.7, -0.4) (0.3, 0.9)0.03 Pre-pregnancy adiposity (Subscapular skinfold (mm)) 1.1 (1.0, 1.2)0.004 Pre-pregnancy physical activity (Walking speed) (0.8, 1.0)0.004 Index of Multiple Deprivation (1.1, 1.3)0.002 EARLY LIFE FACTORS Gestational age (weeks)-0.7 (-1.0, -0.3)<0.001 Length at birth (cm)0.2 (0.2, 0.3)<0.001 Length growth in first year (SD)0.3 (0.2, 0.5)<0.001 Birth weight (kg)-2.7 (-3.6, -1.8)<0.001 BMI(kg/m 2 ) at one year (0.05, 0.2) (1.0, 1.1) Log-transformed 2 Estimates for walking speed are for trend across increasing levels 3 RR: Relative Risk

Results – Associations with risk factors Age of first tooth eruption (weeks) Number of teeth at one year Advanced dentally developed (>16 teeth) at two years MATERNAL FACTORS β (95% CI)P PRR 3 (95% CI)P In pregnancy smoking status (Yes v No)-2.2 (-3.2, -1.1)< (0.5, 1.2)< (1.0, 1.5)0.01 Maternal ethnic origin (Asian v White)2.7 (0.6, 4.7) (-1.7, -0.4) (0.3, 0.9)0.03 Pre-pregnancy adiposity (Subscapular skinfold (mm)) 1.1 (1.0, 1.2)0.004 Pre-pregnancy physical activity (Walking speed) (0.8, 1.0)0.004 Index of Multiple Deprivation (1.1, 1.3)0.002 EARLY LIFE FACTORS Gestational age (weeks)-0.7 (-1.0, -0.3)<0.001 Length at birth (cm)0.2 (0.2, 0.3)<0.001 Length growth in first year (SD)0.3 (0.2, 0.5)<0.001 Birth weight (kg)-2.7 (-3.6, -1.8)<0.001 BMI(kg/m 2 ) at one year (0.05, 0.2) (1.0, 1.1) Log-transformed 2 Estimates for walking speed are for trend across increasing levels 3 RR: Relative Risk

Results – Associations with risk factors Age of first tooth eruption (weeks) Number of teeth at one year Advanced dentally developed (>16 teeth) at two years MATERNAL FACTORS β (95% CI)P PRR 3 (95% CI)P In pregnancy smoking status (Yes v No)-2.2 (-3.2, -1.1)< (0.5, 1.2)< (1.0, 1.5)0.01 Maternal ethnic origin (Asian v White)2.7 (0.6, 4.7) (-1.7, -0.4) (0.3, 0.9)0.03 Pre-pregnancy adiposity (Subscapular skinfold (mm)) 1.1 (1.0, 1.2)0.004 Pre-pregnancy physical activity (Walking speed) (0.8, 1.0)0.004 Index of Multiple Deprivation (1.1, 1.3)0.002 EARLY LIFE FACTORS Gestational age (weeks)-0.7 (-1.0, -0.3)<0.001 Length at birth (cm)0.2 (0.2, 0.3)<0.001 Length growth in first year (SD)0.3 (0.2, 0.5)<0.001 Birth weight (kg)-2.7 (-3.6, -1.8)<0.001 BMI(kg/m 2 ) at one year (0.05, 0.2) (1.0, 1.1) Log-transformed 2 Estimates for walking speed are for trend across increasing levels 3 RR: Relative Risk

Results – Associations with risk factors Age of first tooth eruption (weeks) Number of teeth at one year Advanced dentally developed (>16 teeth) at two years MATERNAL FACTORS β (95% CI)P PRR 3 (95% CI)P In pregnancy smoking status (Yes v No)-2.2 (-3.2, -1.1)< (0.5, 1.2)< (1.0, 1.5)0.01 Maternal ethnic origin (Asian v White)2.7 (0.6, 4.7) (-1.7, -0.4) (0.3, 0.9)0.03 Pre-pregnancy adiposity (Subscapular skinfold (mm)) 1.1 (1.0, 1.2)0.004 Pre-pregnancy physical activity (Walking speed) (0.8, 1.0)0.004 Index of Multiple Deprivation (1.1, 1.3)0.002 EARLY LIFE FACTORS Gestational age (weeks)-0.7 (-1.0, -0.3)<0.001 Length at birth (cm)0.2 (0.2, 0.3)<0.001 Length growth in first year (SD)0.3 (0.2, 0.5)<0.001 Birth weight (kg)-2.7 (-3.6, -1.8)<0.001 BMI(kg/m 2 ) at one year (0.05, 0.2) (1.0, 1.1) Log-transformed 2 Estimates for walking speed are for trend across increasing levels 3 RR: Relative Risk

Discussion Children of mothers who smoked in pregnancy had more advanced dentition Children of mothers of Asian ethnicity had later onset and lower rates of teeth eruption Bigger babies at birth and one year also had earlier eruption patterns Children of mothers who lived in less advantaged areas, were less physically active or more adipose had a faster rate of dental emergence, most apparent at two years

Conclusions There is an apparent impact of health behaviours of women before and during pregnancy, and particularly maternal smoking, on the eruption patterns of primary dentition

Acknowledgements Mums, dads, and children Co-authors Dr Peter F Day Dr Janis Baird Prof Keith M Godfrey Prof Sian M Robinson Prof Cyrus Cooper Prof Hazel M Inskip Funding Medical Research Council British Heart Foundation Arthritis Research UK National Osteoporosis Society International Osteoporosis Foundation NIHR Southampton Biomedical Research Centre University of Southampton Dunhill Medical Trust