Periodontitis treatment in pregnant women during the second trimester did not significantly affect cognitive, motor, and language development in their children at 24 to 28 months of age. Changes in clinical periodontitis measures during pregnancy also were not consistently associated with these outcomes. Although change in clinical attachment loss was associated with cognitive and motor scores (P = .02 and .01, respectively, uncorrected for multiple comparisons), we deem these effect sizes to be of little or no clinical significance.
To our knowledge, this is the first study to explore associations between maternal periodontitis treatment and child development. Emerging evidence suggests that periodontitis and periodontitis-associated bacteria are associated with impaired cognition and memory and incident dementia in adults and the elderly.18–21
Moreover, rodent studies suggest that nonuterine infections elicit systemic inflammatory responses that affect development or activities of neuronal cells in the fetal brain22,23
and that anti-inflammatory drugs can reverse lipopolysaccharide-induced inhibition of neurogenesis.24
Despite the plausibility of such a link, we found no consistent evidence that treatment of bacterial-induced oral inflammation in pregnant women affects motor, language, or cognitive functions in children.
All women in the parent trial had periodontitis, which may explain why mean Bayley scores were lower than national norms. Because we did not study pregnant women without periodontitis, we could not establish whether disease per se was associated with neurodevelopment. The design of the parent trial only enabled us to explore associations with periodontitis treatment and changes in periodontitis status that occurred after 21 weeks of gestation. However, treatment was associated with significant improvements in the mothers' periodontal condition, suggesting that reduced exposure to maternal disease and disease-related microorganisms in midpregnancy do not improve outcomes in children.
At the start of the parent trial, most women had generalized early-to-moderate periodontitis. Because any systemic effect of periodontitis may be more pronounced in severe disease, our findings may have differed had we enrolled only women with advanced periodontitis. However, the prevalence of advanced disease in this age group is low (~1%),25
so even if a treatment effect exists in this subgroup, the public health implications of identifying and treating affected women would be limited.
The study treatment consisted of mechanical therapy (scaling and root planing and monthly tooth polishings). In rare instances, women who were refractory to this treatment were given systemic antibiotics. Sustained-release, locally delivered antibiotics were not used because all such products in the United States are tetracycline derivatives, which are relatively contraindicated during pregnancy because of concerns about embryotoxicity, retarded fetal skeletal development and discoloration of primary teeth. Our results again may have differed had we provided periodontal treatment earlier in gestation (even before conception), repeatedly, or more aggressively (ie, included the routine use of systemic antibiotics or periodontal surgery). Nonetheless, associations that were statistically significant were weak. A 1 SD relative improvement in attachment loss was associated with an ~1-point improvement in motor and cognitive scores, suggesting that even large clinical improvements in the mother yielded only nominal improvements in motor and cognitive scores in the infants.
A limitation of this study is that only about half of eligible women from the parent trial participated. The parent trial recruited from underserved and relatively transient populations. Of women eligible for the current study, 109 (13.8%) declined to participate or withdrew consent (), and even more women simply could not be located. The numbers of treatment and control group women were similar, indicating that the timing of periodontitis treatment was not associated with later study participation. Although the proportion of preterm and low birth weight infants was similar in the 2 groups, mothers of very preterm or very low birth weight infants were less likely to participate than mothers of term or normal birth weight infants. We considered this differential loss to follow-up in weighted analyses, but the low number of very preterm or very low birth weight infants limits our findings to groups at relatively low risk for developmental delay. The relationship between child neurodevelopment and change in maternal status or receipt of treatment during pregnancy may differ in cohorts of only preterm or very preterm infants. As with any study, our findings should be interpreted in terms of characteristics of the women—who were predominantly from minority and lower income groups—and of the range of cognitive, motor, and language scores in these children.
We collected extensive information regarding the child but did not test for associations between individual characteristics and neurodevelopment outcomes. Instead, we grouped covariates into blocks on the basis of when they would be expected to affect neurodevelopment: during pregnancy, in the neonatal period, or before 24 to 28 months of age. We also ignored statistical interactions in the adjusted analyses and instead focused on estimating the effect on development scores of periodontal treatment group or change in periodontitis measures. As noted, the few interactions that were statistically significant were barely so and either described small effects or were noninterpretable.