Dental infections may shorten pregnancy and affect birth size

Mothers with children queue at a child health clinic in Mangochi, Malawi, the site of the study on maternal dental health.

Mothers with children queue at a child health clinic in Mangochi, Malawi, the site of the study on maternal dental health.

Researcher Ulla Harjunmaa with one of the babies who participated in the study.

Researcher Ulla Harjunmaa with one of the babies who participated in the study.

New research conducted in Malawi by researchers from the University of Tampere shows that a mother’s tooth infection may shorten the duration of pregnancy and lead to the birth of a smaller baby. If similar findings are obtained from other countries, premature births and foetal growth restriction can be prevented in the future by investing in dental care for expectant mothers.

“The finding is remarkable because dental caries is the most common chronic illness in the world. Especially in low- and middle-income countries, caries is usually left untreated, which often leads to infection in the tooth and eventually the surrounding bone tissue”, says Ulla Harjunmaa, a dentist and researcher in the study.

Every year, more than 32 million babies are born too small, most of them in South Asia or Sub-Saharan Africa. These children have a higher mortality risk, are more frequently ill and their development is slower than that of babies who are born at a normal size.

A total of 1,024 new mothers participated in the study, which was conducted in the Malawian countryside. The health of the participants’ teeth and oral mucous membranes were examined and their jaws were X rayed. Data on the mothers’ teeth was compared with the duration of pregnancy and the weight, length and head circumference of the babies.

Of the mothers who participated in the study, 23.5 percent had a dental infection that had spread to their jawbones. On average, their pregnancies were 0.4 weeks shorter and their babies 79 grams lighter and 0.5 centimetres shorter than the babies of mothers with healthy teeth.

“These findings are considerable at the population level. The results indicate that nearly 10 percent of premature births and 13 percent of stunting could theoretically be avoided by preventing these infections”, Harjunmaa says.

“Our study is the first to find such an association with dental infections. Our presumption is that the mechanisms are the same as in the previously discovered association between periodontitis and birth size: an infection in the mouth elevates the general immune response, and the bacteria are also capable being transmitted to the uterus via blood circulation.

“Our findings are relevant in Finland, too, where the prevalence of dental caries is increasing and where these often painless chronic infections are commonly found in routine dental check-ups, but health expenditure has been cut back”, Harjunmaa adds.

The research has been published as Association between maternal dental periapical infections and pregnancy outcomes: results from a cross-sectional study in Malawi by Harjunmaa et al. in the journal Tropical Medicine and International Health.

For more information, please contact:
Researcher Ulla Harjunmaa
Tampere Center for Child Health Research at the School of Medicine