Periodontal treatment during pregnancy-no evidence of impact on preterm birth

Routine specialist pregnancy care involved an initial meeting to discuss quitting smoking and set a quit date, followed by 4 weekly telephone calls, and free nicotine replacement therapy for 10 weeks.

Periodontal disease is common and has a tendency to worsen during pregnancy. A number of studies have shown associations between periodontal disease and adverse pregnancy outcomes. It has been hypothesised that might be linked to a systemic increase in proinflammatory prostaglandins and cytokines from microbial infection.

The aim of this review was to assess the effects of treating periodontal disease in pregnant women in order to prevent or reduce perinatal and maternal morbidity and mortality.


Searches were conducted in the Cochrane Oral Health’s Trials Register, Cochrane Pregnancy and Childbirth’s Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, LILACS BIREME, and the World Health Organization International Clinical Trials Registry Platform databases with no restrictions.  Randomised controlled trials (RCTs) comparing periodontal treatment during pregnancy with control or no treatment for preventing or reducing perinatal and maternal morbidity and mortality.

Two reviewers independently selected studies and abstracted data and assessed risk of bias using the Cochrane tool.  Dichotomous outcomes were expressed as risk ratios(RR) and continuous outcomes as mean differences (MD) with 95% confidence intervals (CI). Time to birth was expressed as hazard ratio (HR) with corresponding 95% CI. Meta-analysis was carried out where appropriate.  Overall quality of evidence was assessed using GRADE.


  • 15 RCTs involving a total of 7161 patients were included.
  • All 15 studies were considered to be at high risk of bias.
  • 11 studies compared periodontal treatment with no treatment during pregnancy. No clear difference in difference in preterm birth < 37 weeks was demonstrated in the meta-analysis (11 studies) RR= 0.87, (95%CI; 0.70 to 1.10). [low quality evidence].
  • Meta-analysis (7 studies) provided low-quality evidence that periodontal treatment may reduce low birth weight < 2500 g (9.70% with periodontal treatment versus 12.60% without treatment; RR= 0.67 (95%CI 0.48 to 0.95).
  • It is unclear whether periodontal treatment leads to a difference in
    • preterm birth < 35 weeks, RR = 1.19, (95%CI; 0.81 to 1.76) 2 studies
    • preterm birth < 32 weeks, RR = 1.35, (95%CI; 0.78 to 2.32) 3 studies,
    • low birth weight < 1500g, RR = 0.80, (95%CI; 0.38 to 1.70) 2 studies,
    • perinatal mortality (including fetal and neonatal deaths up to the first 28 days after birth), RR= 0.85, (95%CI; 0.51 to 1.43) 7 studies; [very low-quality evidence]
    • pre-eclampsia,  RR = 1.10, (95%CI; 0.74 to 1.62)2946 3 studies; [very low-quality evidence].
  • There is no evidence of a difference in small for gestational age, RR = 0.97, (95%CI; 0.81 to 1.16) 3 studies; [low-quality evidence].
  • Maternal mortality and adverse effects of the intervention did not occur in any of the studies that reported on either of the outcomes.


The authors concluded: –

It is not clear if periodontal treatment during pregnancy has an impact on preterm birth (low-quality evidence). There is low-quality evidence that periodontal treatment may reduce low birth weight (< 2500 g), however, our confidence in the effect estimate is limited. There is insufficient evidence to determine which periodontal treatment is better in preventing adverse obstetric outcomes. Future research should aim to report periodontal outcomes alongside obstetric outcomes.


The have been a large number of reviews conducted on this topic the last one we looked at was in February 2013 (Dental Elf – 15th Feb 2013). While only one of the included studies in this new review was published in 2013 having a review produced using the high-quality methodology of the Cochrane Oral Health Group is helpful. While 15 RCTs have been included in the review all were considered to be at high risk of bias because of a lack of blinding and baseline imbalances in the characteristics of the patients. Given that all the trials have been conducted since 2000 and the first CONSORT statement was published in 1996 and the SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) Statement has been in place since 2007  it helps to demonstrates that progress on  improving the quality of RCTs in the dental arena has been slow.

The review authors highlight the need for full and clear reporting of both periodontal and obstetric outcomes in future studies and a pressing need for a consensus case definition of periodontal disease linked with more standardised reporting.

From a clinical perspective the key messages a well summarised in the plain language summary of this review:-

There is no evidence that the treatment of gum disease reduces the number of babies born before 37 weeks of pregnancy, however, it may reduce the number of babies born weighing less than 2500 g. It is uncertain whether there is a difference in adverse birth outcomes when different methods of treating gum disease are compared.


Primary paper

Iheozor-Ejiofor Z, Middleton P, Esposito M, Glenny AM. Treating periodontal disease for preventing adverse birth outcomes in pregnant women. Cochrane Database of Systematic Reviews 2017, Issue 6. Art. No.: CD005297. DOI: 10.1002/14651858.CD005297.pub3.

Other references

 Cochrane Oral Health Group Blog – No evidence that treatment of gum disease reduces the number of babies born before 37 weeks of pregnancy


 Dental Elf – 15th Feb 2013

Periodontal treatment, pre-term birth and low birth weight

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