| Abstract|| |
Context: Periodontal disease (PD) is a common infection in the community; however, its relationship with low birth weight (LBW) has not been well-established.
Aims: The aim was to determine the association between maternal PD and LBW.
Settings and Design: A case-control (1:1) study.
Materials and Methods: The study population comprised of women who delivered at the hospital during the study period (September 2011 to February 2012).Women between 18 and 35 years of age, who delivered singleton, live infants during study period with at least 18 teeth were enrolled. Those with pregnancy induced hypertension, gestational diabetes, blood-borne viral infections, periodontal treatment within the past 6 months and valvular heart disease were excluded. Control population was parity matched to the cases.
Statistical Analysis Used: Chi-square test, t-test and univariant and multivariant logistic regression were used to analyze various study findings, and level of significance was set at 5% (P < 0.05).
Results: PD was independently associated with LBW (odds ratio: 4.94, 95% confidence interval: 1.03-23.65, P=0.045). Additionally, conventional risk factors such as maternal height (P=0.029), secondary schooling (<8 years of schooling) (P = 0.001), socio-economic status (P = 0.046), type of family (joint) (P = 0.008), number of ante-natal visits (P = 0.028) and gestational age at birth (<37 weeks) (P = 0.045) showed significant association with LBW.
Conclusions: There seems to be an association between PD and LBW independent of conventional risk factors. Women who had PD were 5 times more likely to deliver LBW infants.
Keywords: Low birth weight, periodontal disease, pregnancy
|How to cite this article:|
Mathew RJ, Bose A, Prasad J H, Muliyil J P, Singh D. Maternal periodontal disease as a significant risk factor for low birth weight in pregnant women attending a secondary care hospital in South India: A Case-control study. Indian J Dent Res 2014;25:742-7
Low birth weight (LBW) continues to be a grave public health concern in many developing nations and has been attributed to maternal infections. ,, As per the UNICEF 2011 report, an estimated 20 million infants are born annually of LBW in the developing world.  South Asia has the highest incidence with 31% of all infants being born of LBW (UNICEF 2006) and India heads the list with 21.5% of infants being of LBW as per the National Family Health Survey 3 statistics. Despite substantial advances in the technical and medical world, India continues to battle the challenge of LBW and its consequences. There is mounting evidence that infections that are remote to the fetal-placental unit can affect the birth outcome. ,,
|How to cite this URL:|
Mathew RJ, Bose A, Prasad J H, Muliyil J P, Singh D. Maternal periodontal disease as a significant risk factor for low birth weight in pregnant women attending a secondary care hospital in South India: A Case-control study. Indian J Dent Res [serial online] 2014 [cited 2019 Oct 21];25:742-7. Available from: http://www.ijdr.in/text.asp?2014/25/6/742/152184
Periodontal disease (PD) and dental caries are two such common oral diseases in the community. ,, PD affects the gums and bones that surround and support the tooth. It varies in severity; manifesting as gingivitis in the initial stages and progressing to advanced PD (periodontitis). Gingivitis, which is characterized by inflammation of gums, swelling and recurrent bleeding is widespread in the community.  Due to the trifling symptoms of gingivitis, it is often neglected, and treatment is seldom sought. Lack of early intervention can results in progression to periodontitis. With the onset of periodontitis, there is progressive destruction of the periodontal ligament and alveolar bone. Pocket formation and loss of attachment ultimately leads to loss of the tooth. The pocket depth is often a good indicator of the extent of PD and once a diagnosis is established, early treatment by means of elimination of any contributing risk factors or routine periodontal therapy can help preserve the periodontium and prevent the loss of teeth.
Periodontal disease in pregnancy is a source of chronic infection, which has the potential to have deleterious effects on the mother and fetus leading to preterm LBW.  Studies which have analyzed the association between maternal PD and adverse birth outcomes, thus far have demonstrated varying strength of association.  The purpose of this study was to determine the association between PD during pregnancy and LBW in a large community hospital.
| Materials and methods|| |
This study was approved by the Institutional review board and ethics committee (IRB Min. No. 7562, dated 9 th August 2011). Written consent was obtained from all study participants prior to enrolment.
A 1:1 case-control study design was employed to determine the association of PD and LBW among patients who delivered at a secondary care center. A mother who had given birth to a live infant of LBW (≤2499 g) in the secondary care hospital labor room and meeting inclusion criteria was considered a case for the purpose of the study and a mother who gave birth to a live infant weighing more than 2500 g was selected as the control (matched for parity). The study population comprised of women who delivered at the hospital during the study period (September 2011 to February 2012).Women between 18 and 35 years of age who delivered singleton, live infants during study period and had at least 18 teeth present were included in the study. Women who had any medical condition such as pregnancy induced hypertension, gestational diabetes, blood-borne viral infections were excluded. Those that had undergone any periodontal treatment within the past 6 months and women who required antibiotic prophylaxis prior to any dental procedures were also excluded.
Eighty cases and 80 controls were identified in the labor room based on the outcome of birth. The sample size was calculated based on the assumption that the prevalence of PD during pregnancy was 30%,  with an expected odds ratio (OR) of 2.5, alpha error at 5% and power at 80%. The principal investigator was blinded to the outcome of birth (i.e. whether the subject was a case or a control) until the dental examination was performed, to avoid any bias.
The study was carried out in a secondary care hospital and the dental examination was performed in the dental outpatient clinic (outpatient department) of the same hospital. The clinic is equipped with a dental chair with an overhead light attached to the unit which was used to provide adequate lighting while examining the oral cavity of the subjects. The presence of PD was determined by a single examiner. Probing was done in six sites per tooth, and the deepest measurement was noted as the pocket depth for that particular tooth. The minimum diagnostic criteria for PD for our study was at least periodontal probing depth (PPD) of 4 mm and clinical attachment loss (CAL) of 2 mm at a given site.  Ten per cent of the sample size (16 subjects) was re-examined by second examiner to ensure quality of the assessment. The kappa agreement between the two investigators was 76.5% for PPD and 81.9% for CAL.
Following dental examination, a two - part questionnaire was administered to the study participants. Demographic details ante-natal and post natal details were collected in the first part and dental history was obtained in the second part of the questionnaire.
The main variables included were the birth weight of the neonate (measured in grams) and the presence of bleeding on probing, calculus, pocket depth and clinical loss of attachment. Socio-economic status (SES) determination, level of education, occupation and per capita income was utilized in the modified Kuppuswamy scale to establish SES level. The scoring system graded the socioeconomic levels into 5 groups (lower <5, upper lower 5-10, lower middle 11-15, upper middle 16-25 and upper 26-29). ,
All data analysis was carried out using Statistical Package for Social Science(IBM SPSS version 16). For ascertaining baseline characteristics of subjects, frequencies and descriptive statistics were performed. Chi-square test was done to test association between categorical variables and independent t-test was utilized to ascertain whether cases and controls were statistically different from each other in terms of mean number of teeth affected by each of the periodontal factors. Strength of association was calculated using OR and 95% confidence interval (95% CI). Multiple logistic regression was employed to control for confounders such as education and SES, maternal height, joint family, previous history of LBW, number of ante-natal visits, and gestational age (GA) at birth.
| Results|| |
Eighty mothers who delivered normal weight infants and 80 mothers who delivered LBW infants during the study period were examined. Demographic profile of cases and controls are depicted in [Table 1]. The mean age of the cases was 23.50 years (SD 3.37) and controls was 23.30 years (SD 3.46) and the mean height of the cases was 151.97 cm (SD 6.35) and controls was 155.02 cm (SD 5.58). Majority of cases and controls had attended school. The mean number of years of school attended by cases was 9.10 (SD 3.62) and controls were 11.39 (SD 3.25). The mean number of people living in a household in the case group was 4.64 (SD 2.11) and control group was 5.40 (SD 2.50).
Higher maternal education and SESs were noted in mothers of infants with normal birth weight (NBW). In addition greater frequency of ante-natal care visits was observed among mothers of NBW infants. Preterm births (PTBs) were present in 13 (16.25%) of the cases as compared to 5 (6.25%) and this difference was statistically significant.
The various periodontal parameters and the association with birth weight are shown in [Table 2]. The comparison showed a significant difference between case and controls for certain parameters. Cases were more likely to have bleeding on probing (OR = 1.66, P = 0.112) and calculus (OR = 1.61, P = 0.168) in comparison to controls, however this was not statistically significant. Forty nine cases and 39 controls had bleeding on probing, and the mean number of teeth with bleeding on probing was 3.40 (SD 4.38) in cases and 2.21 (SD 4.18) in controls. The mean number of teeth with calculus was slightly higher in cases than in controls (P = 0.045).
It was observed that mothers of LBW infants were 3 times more likely to have periodontal pockets ≥4 mm when compared to mothers of NBW infants (P = 0.017). It was also noted that they were twice as likely to have CAL (P = 0.007). Both these observations were statistically significant. Cases who has CAL of 2 mm and ≥3 mm were found to be more likely to deliver LBW infants (OR = 1.90, P = 0.050 and OR = 2.64, P = 0.073 respectively). Mothers who had pockets and CAL ≥ 2 mm at the same site (defined as having PD) were nearly 5 times likely to deliver a LBW infant in comparison to mothers without PD and this observation was statistically significant. The prevalence of the PD among the study subjects was estimated to be 6.9% (11.25% in cases and 2.5% in controls).
In addition, we concurrently studied various known risk factors for LBW [Table 3]. Both univariant and multivariant analysis were done [Table 4]. Univariant analysis showed a significant association between LBW and maternal height <145 cm, secondary schooling or less, low SES, less than three ante-natal visits, GA at birth and presence of PD. More than four members in a household (joint family) were noted to be a significant protective factor.
|Table 4: Univariant and multivariant analysis of risk factors associated with LBW|
Click here to view
Univariant analysis [Table 3] revealed the following; mothers of height less than 145 cm were 4 times more likely to deliver a LBW infant (P = 0.029), mothers who received only secondary schooling to less were 3 times more likely to deliver a LBW infant (P = 0.001), those belonging to low SES and those that had three or less antenatal visits were twice likely to deliver a LBW infant (P = 0.046 and P = 0.028 respectively), mothers who delivered prematurely (<37 weeks) were nearly 3 times like to deliver a LBW infant (P = 0.045). It was also noted that there was a 60% lesser chance for a mother to deliver a LBW infant if she belonged to a joint family (more than four members in the household).
Multi-variant analysis of selected variables was performed to ascertain the association between PD and LBW after adjusting for all possible confounders [Table 4]. PD continued to be significantly associated with low birth weight even after adjusting for maternal age, maternal height, packed cell volume (PCV), SES, GA at birth, type of family and presence of ante-natal risk factors (such as history of neonatal death, pregnancy after prolonged infertility and seizure disorders on mediation). Mothers with PD are 5 times more likely to deliver a low birth weight infant (P = 0.04).
| Discussion|| |
The association between PD during pregnancy and its outcomes have been studied over a decade, but the results have been inconclusive. ,, Studied carried out earlier have assessed a range of pregnancy outcomes such as PTB, LBW and preterm LBW to study the possible association with PD. In our study, we chose to look at only LBW. In our study, we aimed to assess the probability of PD as a risk factor for LBW while differentiating between various other important risk factors for LBW. The findings of our study demonstrate an association between PD and LBW.
Periodontal disease among pregnant women
In our study, a low prevalence of PD was observed in the population studied. However, bleeding on probing was present in 55% and calculus was seen in 112 subjects. PPD of more than 4 mm (pockets) was seen in 25 women, and CAL was noted in 66.2% of subjects. The probable reason for the low prevalence of PD is that most women resided in semi-urban localities and had fairly good level of education.
Prevalence of PD in pregnant women had been studied by many researchers, and diverse estimates have been obtained owing to the variations in the definition of PD. Cruz et al. conducted a case-control study among mothers who delivered LBW and NBW infants and found the prevalence of PD among cases to be 42.7% and 30% among controls.  Shanthi et al. studied the rate of PD among pregnant women in Bhopal which revealed CPI score of 3 in 59% and CAL 1-2 mm in 21.5%.  Kothiwale et al. (2011) ascertained the prevalence of PD (pockets of 5 mm depth) among pregnant women in Belgaum to be 31.3%.  Murthy et al. ascertained the prevalence of pockets of 3.5-4.5 mm among pregnant women in rural Belgaum to be 50%. 
Periodontal disease and low birth weight
Our study found a significant association between PD and LBW. The odds of a woman with PD delivering a LBW infant were nearly 4 times more when compared with a woman without PD (95% CI: 1.03-23.65). After adjusting for possible confounders (such as age, maternal height, PCV, SES, GA at birth, presence of antenatal risk factors and joint family) we obtained an OR of 5.16 (95% CI: 1.03-25.64). The population attributable risk for LBW due to PD was calculated, and we established that 9% of all LBW can be attributed to PD.
The association between PD and preterm LBW delivery has been studied earlier. Offenbacher was the first to determine this association. In a case-control study, they found that the adjusted odds ratio was as high as 7.9 and pointed toward a previously unrecognized risk factor of preterm/LBW.  Dasanayake in a 1:1 matched pair case-control study concluded that mothers with healthier areas of gingiva were at a lower risk of delivering a LBW infant (OR: 0.3, 95% CI: 0.12-0.72).  Cruz et al. conducted a case-control study among mothers who delivered LBW and NBW infants.  They demonstrated a statistically significant association between PD and LBW (unadjusted OR: 1.74; 95% CI: 1.19-2.54), especially in mothers with low schooling levels (adjusted OR: 2.30; 95% CI: 1.14-4.6).  Saddki et al. studied the association between maternal periodontitis and LBW infants among Malay women. The incidence of LBW was 14.2% (95% CI: 9.70-18.75) in women with PD as compared to 3.3% (95% CI: 1.05-5.62) in women without PD. Women with PD were 4 times more likely to have a LBW infant when compared to those without PD (95% CI: 2.01-9.04).The adjusted OR was 3.84 (95% CI: 1.34-11.05.  However, some studies failed to observe any significant association, these studies were mainly conducted in developed nations where the prevalence of both PD and LBW are relatively low. ,,,,,,, The varying results may also be attributed to the different PD definitions employed in the studies.
| Limitations|| |
The definition of PD employed for the study may have led to overestimation of the prevalence of PD.
| Conclusion|| |
Despite the limitations of the study, the findings reveal a significant association between maternal PD and LBW. The findings of this study can potentially contribute in some way to the existing gap in evidence regarding the association between PD and LBW and provide the basis for further larger investigations. A simple and routine periodontal examination early on in pregnancy and appropriate oral hygiene and care during pregnancy is a potential way to reduce the risk of delivering an LBW baby. The possibility, of including periodontal therapy as a part of ante-natal preventive care, should be considered.
| AcknowledgmentS|| |
The study was funded by the institutional fluid research grant.
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Rebecca Joyce Mathew
Department of Community Health, Christian Medical College, Vellore, Tamil Nadu
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3], [Table 4]