Does gum disease delay conception?

“Women who want the best chance of having a baby should make sure they floss their teeth regularly,” reported BBC News.

As the BBC reports, this news story is based on study findings presented at the annual meeting of the European Society of Human Reproduction and Embryology. The study found that women with gum disease took an average of 7.1 months to become pregnant – two months longer than women without gum disease (5.0 months).

The study also found that factos such as smoking, being overweight and being older were associated with taking longer than 12 months to conceive, and that these risks were higher in non-Caucasian women.

This study has not been published in a peer-reviewed journal and so has not been subject to the expert scrutiny of the peer review process. Therefore, it is difficult to say how robust these findings are, and whether or not gum disease really does delay conception. Some caution must be applied when interpreting the results, until more detail is available.

While the study does not prove that having a dental check will speed up the time to conception, there are in any case several good reasons to have regular check-ups. Doing so will help to maintain healthy teeth and gums and is encouraged at all stages of life, including when trying for a baby.

Where did the story come from?

The news report is based on a presentation made at the annual meeting of the European Society of Human Reproduction and Embryology. The accompanying conference abstract gives details on the results of this unpublished research carried out at the University of Western Australia. It is not clear from the abstract who funded the original research.

The study has not yet been published in a peer-reviewed medical journal.

The Daily Mirror and the BBC both make clear that the research was presented at a conference, but neither emphasised that the study has not yet been published in a peer-reviewed journal and so has not been scrutinised by other experts in the field for weaknesses or mistakes.

What kind of research was this?

The aim of this case control study was to assess whether having gum disease (periodontal disease) affected the time it took to conceive in a selected group of recently pregnant women in Western Australia.

The researchers report that gum disease creates inflammation that can set off a cascade of tissue-destructive processes that could pass into the circulation. They say that gum disease has previously been associated with cardiovascular disease, type 2 diabetes, respiratory disease, kidney disease and adverse pregnancy outcomes.

What did the research involve?

The pregnant women in this research were already enrolled in another study called SMILE. The SMILE study was a randomised controlled trial of treatment for gum disease in mid-pregnancy, which took place in one research centre. The researchers followed a group of 3,737 pregnant women recruited to the SMILE study and analysed information on pregnancy planning and pregnancy outcomes for 3,416 of them.

The women enrolled into the study were given a questionnaire asking about demographic, dental and medical aspects of their health. Also included were questions about the amount of time taken to conceive (TTC), whether the pregnancy was planned and whether the woman required fertility treatment to conceive.

Information on TTC was available for 1,956 women. The researchers looked at a subset of women who took longer than 12 months to conceive and assessed how they were different from women who took less than 12 months. They also looked at how gum disease risk compared between Caucasian and non-Caucasian women.

The results were adjusted for other factors that are known to influence the time taken to conceive, such as ethnicity, weight and smoking.

What were the basic results?

Of the 1,956 women for whom there was TTC information, 146 (7.5%) took longer than 12 months to conceive. These women were on average significantly older (by one year), more likely to be non-Caucasian, have a body mass index above 25kg/m2 (overweight) and be a smoker than the group of women who took less than 12 months to conceive.

The prevalence of gum disease was significantly greater in women who took more than 12 months to conceive compared to those who took less than a year (34.9% vs. 25.7%, p=0.015). Women with gum disease took an average of 7.1 months to become pregnant – two months longer than the average of 5.0 months that it took women without gum disease to conceive.

Gum disease was found in 23.8% of Caucasian women and 41.4% non-Caucasian women.

Having adjusted for other risk factors, non-Caucasian women with gum disease were 2.88 times more likely to take longer than a year to conceive compared to Caucasian women with gum disease (odds ratio 2.88, 95% confidence interval 1.62 to 5.12).

Having a BMI over 25kg/m2 and smoking were also significantly associated with taking longer than 12 months to conceive. It is not clear what other individual risk factors were accounted for in this analysis, as full details of these were not in the abstract.

How did the researchers interpret the results?

The authors conclude that the presence of gum disease is a “modifiable risk factor limiting a woman’s time to conceive, particularly for non-Caucasians”. They go on to say that the additional two months of time it takes to conceive with gum disease is “of the same order as obesity”.

The authors highlight that gum disease is easily treated and that “all non-Caucasian patients attempting to conceive should be encouraged to have a dental check-up prior to conceiving” and should receive information about stopping smoking, weight loss and folate supplementation.

Conclusion

This research was presented at the Reproduction and Embryology annual conference and has not yet been published in a peer-reviewed journal. Because of this and the fact that this appraisal is based on a conference abstract, which lacked detail, it is difficult to draw any meaningful conclusions at present. However, it is worth noting that:

• The biological mechanism of how gum disease might delay conception has not been established. Another possibility is that poor oral health is a sign of poor general health, which could affect fertility. The authors adjusted for BMI and smoking in their analysis but there may be many other indicators of poor health that influence conception that were not considered, such as alcohol consumption. The potential link between oral health and conception needs to be better understood through further research.
• It is not clear why so few women (1,956 of the 3,416 eligible) had information on TTC available for analysis. This may be because of a poor response rate to the questionnaire. Had the missing information on the remaining 1,460 women been included in the analysis it may have changed the results and the authors’ conclusions.

At present, it is difficult to conclude that gum disease affects fertility. However, regular trips to the dentist to maintain healthy teeth and gums are encouraged at all stages of life, and this includes when trying for a baby.