The popular saying: 'gain a child, lose a tooth' suggests that fertility may be linked to tooth loss, but there are no hard data to back this up.
‘Women with three kids had an average of four fewer teeth than moms with two children.’
To try and plug this gap, the researchers drew on data from Wave 5 of the Survey of Health, Ageing, and Retirement in Europe (SHARE).
SHARE contains information on the health, educational attainment, and household income of more than 120,000 adults aged 50+ from 27 European countries plus Israel.
Wave 5 was conducted in 2013, and included questions on the full reproductive history and number of natural teeth of 34,843 survey respondents from Austria, Belgium, Czech Republic, Denmark, Estonia, France, Germany, Italy, Luxembourg, The Netherlands, Slovenia, Spain, Switzerland and Israel.
The average age of the respondents in Wave 5 was 67, and they reported an average of 10 missing teeth--normally adults have 28 plus 4 wisdom teeth in their mouth.
As might be expected, tooth loss increased with age, ranging from nearly 7 fewer teeth for women in their 50s-60s up to 19 fewer teeth for men aged 80 and above. Higher levels of educational attainment were also linked to lower risk of tooth loss among women
The researchers looked at the potential impact of having twins or triplets rather than singletons, and the sex of the first two children, on the assumption that if the first two were of the same sex, the parents might be tempted to try for a third child.
They applied a particular type of statistical technique (instrumental variables regression), which exploits random natural variation in a variable that is only associated with the exposure and affects the outcome only through that exposure, so mimicking a randomised controlled trial.
A third child after two of the same sex was associated with significantly more missing teeth for women, but not men, if compared with parents whose first two children were different sexes.
This suggests that an additional child might be detrimental to the mother's, but the not the father's, mouth health, say the researchers.
They acknowledge that their analyses covered narrow groups with particular types of fertility patterns, and relatively small numbers in the groups of interest, so the results should be interpreted with caution and taken as evidence of cause only for this small group.
What's more, the precise contribution of parenting rather than pregnancy related factors needs to be unravelled further, they say.
But they conclude: "On the basis of our findings, enhanced promotion of oral hygiene, tooth friendly nutrition and regular (preventive) dental attendance - specifically targeted at expecting and parenting mothers - seem to be sensible strategies for clinicians and health policy."