History of Periodontal Treatment and Risk for Intrauterine Growth Restriction (IUGR)

Cande V. Ananth; Howard F. Andrews; Panos N. Papapanou; Angela M. Ward; Emilie Bruzelius; Mary Lee Conicella; David A. Albert

Disclosures

BMC Oral Health. 2018;18(161) 

In This Article

Discussion

The results indicate an association between maternal periodontal disease and odds of IUGR. We observed significantly elevated odds of IUGR among women who experienced periodontal disease during pregnancy, as evidenced by periodontal treatment shortly after giving birth. We also found that delivery of a higher volume of periodontal treatment, a possible indicator of more severe periodontal disease, was associated with increased incidence of IUGR. The effect was strongest among those who received periodontal treatment after giving birth, an indication of untreated periodontal disease during pregnancy. While relatively few women received periodontal treatment during pregnancy, the sensitivity analysis suggested that there may be elevated risk of IUGR during this period as well. However, contrary to our initial hypothesis, the risk of IUGR in relation to the timing of the receipt of dental treatment did not vary by parity.

Limitations of the Data

Diagnosis of IUGR was based on ICD coding, and this may have introduced some misclassification. Women carrying IUGR fetuses, particularly those that are diagnosed as not being severely growth restricted, are less likely to undergo clinician-initiated obstetrical intervention (labor induction or a prelabor cesarean) and less likely to have a diagnosis of IUGR recorded.[12] However, for severe IUGR (e.g., estimated fetal weight below the third or the first percentiles), misclassification of IUGR status is very unlikely since growth restriction serves as a sentinel cause for obstetrical intervention, and is therefore billed for insurance reimbursement. For the same reason, we believe the recording of the exposure is accurate in this data system because periodontal treatment is the basis for a reimbursable claim.

Second, despite adjustment for several confounders, we lack data on smoking and maternal pre-pregnancy body-mass index. However, the sensitivity analysis conducted to determine the potential effect of unmeasured confounding indicates that our models are robust. Finally, dental data is based on CDT codes that reflect treatment of periodontal disease rather than diagnosis. However, we believe that the treatment codes are sufficiently specific to infer presence of periodontal disease. While women included in this study are from virtually all states in the US, the insured populations are from middle to higher-income socioeconomic strata. This should be considered while generalizing the results from the study; however, it is unlikely that the association between IUGR and infections in general, and periodontal disease in particular, would be any lower among poorer women than among those we studied.

It may appear anomalous in terms of causal reasoning that the relationship we report is between an outcome (IUGR) that occurs prior to an exposure (periodontal treatment in the period immediately after birth). However, periodontal disease is a chronic condition. Therefore, it is plausible to assume that women who were treated in the immediate post-gestation period experienced periodontitis and its systemic impact during gestation.

Finally, while we report that there is an increase in the rate of IUGR as a function of increasing number of treatments for periodontal disease, there are many factors that determine frequency of treatment; therefore, this finding is only suggestive of a relationship between the severity of periodontal disease and increased risk of IUGR.

Strengths of the Study

In this study, a large sample of integrated medical and dental claims data provided a unique opportunity to explore the association between IUGR and periodontitis. In addition, the findings appear robust following adjustment for observed confounders, in fact correction for unmeasured confounding makes the associations stronger. Conducting secondary analyses using insurance data to shed light on the possible causes of negative birth outcomes is highly economical, and valuable in suggesting directions for future research.

Biological Interpretations

The finding that periodontal treatment post-gestation was associated with an increased risk of IUGR in a large national sample add to the growing body of literature indicating a relationship between periodontal infection and related inflammation with adverse birth outcomes.[4–8,13] Periodontal treatment in the period immediately following gestation is interpreted as signifying that periodontal disease was present during gestation. The inflammatory process associated with periodontal disease and the presence of periodontal pathogens in the blood can affect the fetus and the placenta.[4]

This study utilized periodontal treatment as a proxy for the presence of periodontal disease. Periodontal treatment during gestation was expectedly rare and was also low during the pre-gestational period; our sample size was therefore too small to evaluate effects of treatment during pre-gestation and gestation. We expect that treatment during the pre-gestational and gestational periods to have limited adverse impact on birth outcomes. Tonetti and colleagues observed a short term increase in the systemic inflammatory response immediately following periodontal treatment which was then followed by a decrease in inflammation.[14] The finding that deleterious effects associated with periodontal therapy are short-lived is consistent with our finding of no statistically significant effect of treatment in the period prior to gestation and during gestation. However, periodontal treatment provided immediately following birth, which we found to be significantly related to IUGR appears to be a marker of disease during gestation.

Boggess and colleagues also observed that the incidence of small for gestational age increased with periodontal disease severity.[15] These findings are consistent with observations by several other investigators. In a study of Brazilian women, Siqueria and colleagues found increased odds of IUGR (adjusted OR 2.06, 95% CI 1.07, 4.19) among women diagnosed with periodontitis.[16] Similarly, Kumar and colleagues reported an increased association between periodontitis and IUGR, which was attenuated after adjusting for confounders.[17] The associations that we report are very similar to those of the Brazilian study.

The insured and employed population in our analyses is in the upper quartile of income in the United States and would be expected to have better oral hygiene and prevention practices. In addition, it is expected that utilizing treatment as a proxy for periodontal disease to some extent underestimates the true incidence of periodontal disease. In our analytical sample, maternal periodontal disease, indirectly assessed through the delivery of periodontal treatment in the immediate post-partum period, affected 9% of the women. By comparison, earlier studies have reported prevalence rates of 56–61% for maternal periodontitis.[18,19] It should be noted that while we and Siquiera and colleagues[16] observed an increased odds for growth restriction with periodontal disease, other studies did not find such a relationship.[20]

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