The old wives tale which states ‘gain a child and lose a tooth’ is true, new research suggests.

The idea that tooth loss is associated with pregnancy has been a popular myth for hundreds of years, but there has been little evidence to show that mothers should take it seriously.

Now researchers has discovered that women who have three children have on average four fewer teeth than those who have had just two.

It is thought that pregnancy hormones interfere with calcium absorption, leaving teeth vulnerable, as well as promoting gum disease.

There is also a fear that pregnancy cravings make women more likely to eat sugary or acidic treats which damage enamel and cause cavities. Mothers with several children may also be more likely to eat the junk food that their youngsters are eating and have less time to visit the dentist.

Writing in the Journal of Epidemology & Community Health, Professor Stefan Listl, of the Department of Dentistry, Radboud University Nijmegen, The Netherlands, said: “Our study provides unique and novel evidence for causal links between the number of natural children and missing teeth.

“On 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.