Abstract
Objective: This observational cross-sectional study aimed to evaluate systemic and oral conditions in pregnant women with excessive pre-pregnancy weight (PEW) and normal pre-pregnancy weight (PNW) who underwent follow-up in the private healthcare system during the third trimester of pregnancy. Methods: Fifty pregnant women were evaluated from August 2017 to February 2018 and divided into two groups: women with PEW (n = 25); and those with PNW (n = 25). Their weight and body mass index (BMI), periodontal disease status, stimulated salivary flow, and systemic condition were evaluated. Statistical analyses were conducted using t-test, Mann–Whitney test, chi-square test and binary logistic regression (P < 0.05). Results: The groups did not differ in age, educational level or monthly household income (P > 0.05). The PEW group had a higher frequency of arterial hypertension (P = 0.019) and excessive weight gain during gestation (P = 0.010), sought dental services less frequently, and had increased severity of periodontitis (P < 0.0001). Both groups presented low salivary flow, with no intergroup difference. In the final binary logistic regression models, high maternal pre-pregnancy BMI was a significant predictor of arterial hypertension and periodontitis during the third trimester of gestation; maternal excessive weight gain was also a significant predictor of periodontitis during pregnancy. Conclusion: Women with PEW who underwent follow-up in a private healthcare system had a higher prevalence of arterial hypertension and worse periodontal status during the third trimester of pregnancy as compared to women with normal weight.
Key words: Periodontal disease, pregnant women, obesity
INTRODUCTION
Obesity is a chronic and inflammatory disease that may be associated with systemic disorders, such as arterial hypertension, atherosclerosis, diabetes mellitus and obstructive sleep apnoea1; moreover, studies have indicated that it is associated with oral alterations, such as gingivitis and periodontitis1.
C-reactive protein (CRP) was one of the inflammatory mediators of the association between gingivitis and obesity, suggesting that the presence of a low-grade systemic inflammation due to obesity may trigger increased local inflammatory response to external stimuli such as dental plaque2. In general, in patients with excessive weight, the adipose tissues secrete inflammatory cytokines and adipokines, such as tumor necrosis factor-α (TNF-α)1, interleukin-6 (IL-6)3, adiponectin4, leptin5, adipocytokines6 and cytoplasmic enzymes7, which reduce the immune response of the host and mediate generalised systemic inflammation8. Therefore, overweight or obese patients may present with greater local inflammation in the periodontium in the presence of even a small amount of bacterial plaque, resulting in periodontal disease9., 10., 11..
In addition to the role of obesity/overweight status as a contributing factor in systemic inflammation, metabolic and physiological changes occur in a woman’s body during pregnancy, mainly due to high oestrogen and progesterone levels12. Therefore, high levels of gestational hormones reduce the immune response of pregnant women, and exacerbate the inflammatory response. These alterations during pregnancy may cause systemic and oral disorders13. As occurs in the mechanistic pathways of obesity, in the presence of a small amount of bacterial plaque, pregnant women may present with greater local inflammation in the periodontium. In the second trimester, there is a significant increase of gingivitis and ratio of anaerobic to aerobic bacteria13. In this period, there is a correlation between the plasma levels of oestrogen and progesterone, and the presence of Bacteroides melaninogenicus sp. intermedius. Moreover, there is an increase in the probing depth during pregnancy, which is attributed to the location of the gingival margin coronally due to swelling induced by inflammation13., 14..
The association between excessive weight and pregnancy should be clarified because overweight status and obesity may be a risk factor for adverse pregnancy outcomes, such as arterial hypertension, preeclampsia, gestational diabetes mellitus, excessive foetal growth, preterm birth, and the need for Caesarean section and suction/forceps delivery15.
Considering that both obesity and pregnancy may negatively impact the periodontal condition, the periodontal response should be assessed in pregnant women with obesity during pregnancy. Reports have indicated the association between overweight/obese status and periodontitis during pregnancy16., 17., 18., 19., 20., 21.. However, due to the heterogeneity of definition of periodontitis and obesity in those studies, comparison between studies is not possible.
The associations among excessive weight, gestation and periodontitis may be related to hypertension and diabetes mellitus10., 13..
Considering that gestational follow-up in private healthcare systems ensures the provision of integrated and multi-professional treatment to patients, the objective of this study was to evaluate the association between excessive weight and systemic and oral conditions in pregnant women under the Brazilian private healthcare system.
MATERIALS AND METHODS
STROBE guidelines were followed to ensure accurate reporting of the results of this observational cross-sectional study22.
Ethical aspects
This study was conducted in accordance with the tenets of the Declaration of Helsinki (2008), and was approved by the Ethics Committee on Human Research of the Bauru School of Dentistry, University of São Paulo. Written informed consent was obtained from all patients prior to participating in the study.
Sample composition
A total of 63 pregnant women were evaluated; of these, 13 patients were excluded due to the following reasons: of final-week gestational age (n = 7); need for absolute rest (n = 3); smokers (n = 3); underweight (n = 2); using antibiotics (urinary infection; n = 1). Therefore, 50 pregnant women in their third trimester (between 27th and 35th gestational weeks) under the private healthcare system were included. Gestational age was considered as the gestational week from the patients’ last monthly period.
These pregnant women underwent routine assessment at seven private healthcare clinics, and were subsequently referred to our research team at Bauru School of Dentistry. All patients were recruited between August 2017 and February 2018. As the gingival inflammation triggered by biofilm can be accentuated mainly during the second and third trimesters of gestation13., 14., women in the third trimester were recruited in the study sample. Pregnant women were divided into two groups according to their pre-pregnancy nutritional status determined through review of the patients’ obstetric records of pre-pregnancy weight and body mass index (BMI): excessive pre-pregnancy weight (PEW; n = 25), BMI of ≥ 25.0 kg/m2; normal pre-pregnancy weight (PNW; n = 25), BMI of 18.5–24.9 kg/m223.
In this study, pre-pregnancy BMI was considered as the main variable to assess the impact of elevated BMI throughout the gestation period.
Eligibility criteria were: good systemic health before pregnancy, regular gestational follow-up, and third trimester of pregnancy (between 27th and 35th gestational weeks). Patients with general impairments, neuromotor or communication difficulties, diabetes and/or decompensated hypertension, cigarette/drug/alcohol consumption, severe gestational problems requiring absolute rest, or use of medications that could harm oral health, were excluded from the study.
General evaluations
Level of education, monthly income of the household, systemic conditions (such as presence of gestational diabetes mellitus and arterial hypertension), and oral hygiene behaviours were assessed.
Level of education was graded as: 0 = illiteracy; 1 = started but did not complete primary education; 2 = completed primary education; 3 = started but did not complete high school; 4 = completed high school; 5 = started but did not complete higher education; 6 = completed higher education; 7 = specialisation; 8 = Master’s degree; 9 = PhD. Each patient’s highest education level was registered.
Monthly household income was categorised into the following levels: Level I = family income ≤ R$ 937.00; Level II = family income between R$ 937.01 and R$ 1,874.00; Level III = family income between R$ 1,874.01 and R$ 2,811.00; Level IV = family income between R$ 2,811.01 and R$ 3,748.00; Level V = family income between R$ 3,748.01 and R$ 4,685.00; Level VI = family income ≥ R$ 4,685.01. The amount of R$ 937.00 (approximately USD 242.00) was considered as the minimum wage per Brazilian government specification.
Information regarding the presence or absence of gestational diabetes mellitus and arterial hypertension during pregnancy were obtained from the patients’ obstetric records. A score of 0 indicates the absence of these conditions, and a score of 1 indicates the presence of these systemic disorders during pregnancy.
Oral hygiene behaviours, such as daily tooth-brushing frequency, daily use of dental floss and regular dental appointments (once per year) before the gestational follow-up, were assessed.
Anthropometric parameters
At the third-trimester appointment, pre-pregnancy weight and BMI were obtained from the patient’s medical records, and the patients’ height was confirmed by using a stadiometer (Wood 2.20, WCS Ind., Curitiba, Brazil). Maternal weight and BMI during the third trimester of pregnancy were obtained using an automatic scale (MIC model 300PP, Micheletti Ind., 300-kg maximum capacity, São Paulo, Brazil).
Excessive weight gain during pregnancy was classified according to the protocol established by the Institute of Medicine24. This classification establishes the recommended weight gain during gestation according to the patients’ BMI before pregnancy (Table 1). Patients were classified with excessive weight gain if at the time of data collection they presented weight gain above the highest point of the range recommended by the protocol.
Table 1.
Weight gain classification according to maternal BMI before pregnancy22
| Nutritional status before pregnancy | BMI (kg/m2) | Recommended weight gain (kg) |
|---|---|---|
| Underweight | < 18.5 | 12.5–18 |
| Normal weight | 18.5–24.9 | 11–16 |
| Overweight | 25.0–29.9 | 7–11.5 |
| Obesity | ≥ 30.0 | 5–9 |
BMI, body mass index.
Oral examination
Oral examinations were conducted during the third trimester of pregnancy (between 27th and 35th gestational weeks) by one trained dentist (inter-examiner kappa = 0.92; intra-examiner kappa = 0.95). These data were collected at the same appointment at which gestational anthropometric measurements were obtained. For periodontal status, probing pocket depth (PPD) and clinical attachment level (CAL) were assessed with a standard periodontal clinical probe (QD.320.05; Quinelato, Schobell Ind. Ltda, Rio Claro, São Paulo, Brazil). PPD was measured from the free gingival margin to the bottom of the periodontal pocket, and CAL was measured from the cemento-enamel junction to the base of the periodontal pocket25. Six sites (mesial buccal, cervical buccal, distal buccal, mesial lingual, cervical lingual and distal lingual) were assessed for each tooth, excluding the third molars. Periodontitis was classified as follows: mild, presence of two or more interproximal sites with CAL of ≥ 3 mm (not on the same tooth), or two or more interproximal sites with PPD of ≥ 4 mm (not on the same tooth), or one site with PPD of ≥ 5 mm; moderate, presence of two or more interproximal sites with CAL of ≥ 4 mm (not on the same tooth), or two or more interproximal sites with PPD of ≥ 5 mm (not on the same tooth); severe, presence of two or more interproximal sites with CAL of ≥ 6 mm (not on the same tooth) and one or more interproximal site(s) with PPD of ≥ 5 mm26.
For evaluation of gingival inflammation, bleeding on probing (BOP) was measured at each assessment site pre-categorised by the presence or absence of bleeding, according to the method of Ainamo and Bay27. The results obtained were presented according to the prevalence of sites with BOP, and the absence or presence of gingivitis classified according to the definition provided by Lang et al.28 of the presence of ≥ 30% sites with BOP. The presence of dental calculus was assessed through visual and tactile examination of each tooth: a score of 0 was assigned in the case of absence of dental calculus; and a score of 1 was assigned in the case of presence of dental calculus. In addition, the percentage of teeth with calculus was assessed.
Salivary flow was evaluated by measuring the level of stimulated saliva. Patients were instructed to chew a piece of sterile rubber (0.5–1.0 cm of latex tube) attached to a piece of dental floss of 30-cm length. The amount of saliva collected in the first minute was discarded. The total volume of saliva collected in 5 minutes was deposited in a disposable cup and measured using a 5-mL hypodermic syringe. Salivary flow was considered normal at the level of > 1 mL secreted volume per minute29.
Statistical analysis
Statistical analysis was performed with IBM SPSS Version 25 (IBM SPSS Statistics for Windows, Version 25.0; IBM, Armonk, NY, USA). For sample size calculation, the alpha power hypothesis test was adopted, considering a difference of at least 10%, with standard deviations of 10%, between the PPDs among the groups. The Kolmogorov–Smirnov test was applied to verify normal distribution of the sample. Statistical analysis was performed in two steps: bivariate analysis and binary logistic regression using the stepwise backward (likelihood ratio) method. In bivariate analysis, t-test was applied to the quantitative variables with normal distribution (maternal age; pre-pregnancy weight and BMI; height; weight and BMI during the third trimester of pregnancy; percentage of dental calculus; percentage of sites with BOP). The Mann–Whitney test was applied for assessment of the quantitative variables with non-normal distribution and ordinal qualitative variables (level of education; monthly household income; daily tooth-brushing; mean of PPD; percentage of sites with PPD of ≥ 4 mm; mean of CAL; percentage of sites with CAL of ≥ 4 mm; severity classification of periodontitis; salivary flow). Chi-square test was used for nominal qualitative variables (presence/absence of arterial hypertension during gestation and gestational diabetes mellitus; daily use of dental floss; regular dental appointment; recommended weight gain classification during pregnancy; presence/absence of gingivitis; presence/absence of periodontitis; presence/absence of low salivary flow). According to standardised statistical criteria, all independent variables that yielded P < 0.20 in bivariate analyses were included in the initial model of logistic regression to evaluate their possible influence on the dependent variables. Hosmer–Lemeshow, collinearity, and residual analyses were implemented to explain the results obtained through logistic regression. A statistical significance level of 5% was adopted.
RESULTS
The results of bivariate analysis of the group-wise comparisons of general characteristics are shown in Tables 2 and 3. No inter-group differences were found in terms of age, level of education, monthly household income, and diabetes mellitus during pregnancy. The PEW group had a greater weight and higher BMI before and during pregnancy. However, there was no statistically significant difference between groups in terms of height. Thirteen patients in the PEW group (52%) were classified as overweight and 12 (48%) were obese. None of the patients had low weight gain during pregnancy. Eight patients in the PEW (32%) group had high weight gain according to the Institute of Medicine guideline, while only one (4%) patient in the PNW group had high weight gain. Moreover, five patients in the PEW group (20%) had arterial hypertension during pregnancy, whereas none of those in the PNW group had that systemic gestational change.
Table 2.
Comparison of contextual variables and systemic conditions between groups
| Variables Mean ± SD Median [1st–3rd quartiles] |
PEW (n = 25) | PNW (n = 25) | P |
|---|---|---|---|
| Maternal age (years) | 30.80 ± 4.63 | 30.60 ± 5.19 | 0.886* |
| Pre-pregnancy weight (kg) | 81.19 ± 14.49 | 58.62 ± 6.85 | < 0.0001* |
| Maternal height (m) | 1.63 ± 0.06 | 1.62 ± 0.04 | 0.865* |
| Pre-pregnancy BMI (kg/m2) | 30.46 ± 5.04 | 22.03 ± 2.05 | < 0.0001* |
| Maternal weight (kg) in 3rd trimester | 88.93 ± 14.53 | 67.54 ± 7.95 | < 0.0001* |
| Maternal BMI (kg/m2) in 3rd trimester | 33.27 ± 4.75 | 25.46 ± 2.64 | < 0.0001* |
| Weight gain during pregnancy (kg) | 8.77 ± 7.38 | 8.31 ± 3.81 | 0.929* |
| Level of education | 6 [4.00–6.25] | 6 [5.75–7.25] | 0.135† |
| Monthly income of the household | 5 [3–6] | 6 [5–6] | 0.086† |
| Gestational AH | |||
| No | 20 | 25 | 0.019‡ |
| Yes | 5 | 0 | |
| Gestational diabetes mellitus | |||
| No | 22 | 25 | 0.077‡ |
| Yes | 3 | 0 | |
| High weight gain during pregnancy | |||
| No | 17 | 24 | 0.010‡ |
| Yes | 8 | 1 | |
AH, arterial hypertension; BMI, body mass index; PEW, pregnant women with excessive weight; PNW, pregnant women with normal weight.
t-test.
Mann–Whitney.
Chi-square.
Table 3.
Comparison of oral hygiene behaviour and oral parameters between groups
| Variables Mean ± SD Median [1st–3rd quartiles] |
PEW (n = 25) | PNW (n = 25) | P |
|---|---|---|---|
| Number of times of tooth-brushing per day | 3 [3–3] | 3 [2.75–3.00] | 0.696† |
| Salivary flow (mL/min) | 0.70 [0.56–1.14] | 0.78 [0.60–1.04] | 0.961† |
| PPD average (mm) | 2.20 [2.01–2.28] | 1.95 [1.90–2.02] | 0.0003† |
| % of sites with PPD ≥ 4 mm | 2.27 [0.65–4.80] | 0 [0–0] | < 0.0001† |
| CAL average (mm) | 2.20 [2.10–2.30] | 1.98 [1.90–2.03] | 0.0001† |
| % of sites with CAL ≥ 4 mm | 2.56 [1.63–4.80] | 0 [0.00–0.60] | < 0.0001† |
| Periodontitis severity | 2 [2–2] | 0 [0–0] | < 0.0001† |
| Absent – n (%) | 5 (20%) | 24 (96%) | |
| Mild – n (%) | 0 (0%) | 0 (0%) | |
| Moderate – n (%) | 19 (76%) | 1 (4%) | |
| Severe – n (%) | 1 (4%) | 0 (0%) | |
| Prevalence of dental calculus (%) | 38.93 ± 26.67 | 29.03 ± 22.93 | 0.166* |
| Prevalence of BOP (%) | 36.82 ± 15.76 | 25.77 ± 10.58 | 0.005* |
| Daily use of dental floss | |||
| No | 11 | 7 | 0.243‡ |
| Yes | 14 | 18 | |
| Regular dental care by professional | |||
| No | 15 | 7 | 0.024‡ |
| Yes | 10 | 18 | |
| Salivary flow | |||
| Normal | 9 | 8 | 0.767‡ |
| Below normal | 16 | 17 | |
| Gingivitis | |||
| No | 7 | 19 | 0.0008‡ |
| Yes | 18 | 6 | |
| Periodontitis | |||
| No | 5 | 24 | < 0.0001‡ |
| Yes | 20 | 1 | |
BOP, bleeding on probing; CAL, clinical attachment level; PEW, pregnant women with excessive weight; PNW, pregnant women with normal weight; PPD, probing pocket depth.
*t-test.
Mann–Whitney.
Chi-square.
There was no inter-group difference with respect to oral hygiene behaviours; nevertheless, the PEW group had a lower frequency of regular dental care by professionals (P = 0.024; Table 3). In terms of oral condition, the PEW group presented a higher frequency of gingivitis and periodontitis. Nineteen (76%) patients in the PEW group had moderate periodontitis and one patient (4%) had severe periodontitis, whereas only one (4%) patient in the PNW group had moderate periodontitis. There were no inter-group differences in terms of salivary flow. However, both PEW and PNW groups had a high frequency of patients with salivary flow below normal (64% and 68%, respectively).
Binary logistic regression analysis was performed to identify independent predictors of arterial hypertension (0 = no AH; 1 = AH) during the third trimester of pregnancy (Table 4). The initial model was composed of the following variables: Pre-pregnancy BMI, excessive weight gain, and periodontitis during pregnancy. In the multicollinearity analysis, all independent variables had values of tolerance of > 0.60 and variance inflation factor values of < 2. Pre-pregnancy BMI [adjusted odds ratio (OR) = 1.27; 95% confidence interval (CI) = 1.04–1.57; P = 0.021] was a significant predictor of AH during the third trimester of pregnancy according to the final model of logistic regression [χ2(1) = 8.78; P = 0.003; R2 of Nagelkerke = 0.337]. The overall accuracy of the final model was 92%. In the Hosmer–Lemeshow analysis, a chi-square value for the final model of 5.02 for 8 degrees of freedom (P = 0.755) was obtained.
Table 4.
Binary logistic regression model showing the independent variables related to AH during the third trimester of pregnancy
| B | P | Adjusted OR | 95% CI | |
|---|---|---|---|---|
| Model 1 | ||||
| Pre-pregnancy BMI | 0.27 | 0.030 | 1.31 | 1.02–1.68 |
| Excessive weight gain | −1.83 | 0.153 | 0.16 | 0.01–1.97 |
| Periodontitis | 0.26 | 0.846 | 1.29 | 0.09–17.68 |
| Constant | −9.09 | 0.013 | 0.0001 | |
| Model 2 | ||||
| Pre-pregnancy BMI | 0.27 | 0.023 | 1.32 | 1.04–1.68 |
| Excessive weight gain | −1.88 | 0.131 | 0.15 | 0.01–1.75 |
| Constant | −8.99 | 0.011 | 0.0001 | |
| Final model | ||||
| Pre-pregnancy BMI | 0.24 | 0.021 | 1.27 | 1.03–1.56 |
| Constant | −9.22 | 0.005 | 0.0001 | |
Adjusted OR, adjusted odds ratio; B, coefficient; BMI, body mass index; CI, confidence interval.
Binary logistic regression was performed to verify the independent predictors of periodontitis (0 = no periodontitis; 1 = periodontitis) during the third trimester of pregnancy (Table 5). The initial model was composed of the following variables: pre-pregnancy BMI, AH during pregnancy, regular professional dental care, and excessive weight gain during pregnancy. In the multicollinearity analysis, all independent variables presented tolerance values of > 0.70 and variance inflation factor values of < 2. Pre-pregnancy BMI (adjusted OR = 1.37; P = 0.001) and excessive weight gain during pregnancy (adjusted OR = 0.13; P = 0.034) were the predictive variables that remained in the final logistic regression model [χ2(2) = 24.11; P < 0.0001; R2 of Nagelkerke = 0.515] related to periodontitis during the third trimester. The overall accuracy of the final model was 86%. In the Hosmer–Lemeshow analysis, a chi-square value for the final model of 19.87 for 8 degrees of freedom (P = 0.011) was obtained.
Table 5.
Binary logistic regression model showing the independent variables related to periodontitis during the third trimester of pregnancy
| B | P | Adjusted OR | 95% CI | |
|---|---|---|---|---|
| Model 1 | ||||
| Pre-pregnancy BMI | 0.31 | 0.002 | 1.37 | 1.12–1.67 |
| AH | 0.35 | 0.802 | 1.43 | 0.08–23.30 |
| Regular dental care by professional | −0.86 | 0.266 | 0.42 | 0.09–1.93 |
| Excessive weight gain during pregnancy | −2.12 | 0.047 | 0.11 | 0.01–0.96 |
| Constant | −6.76 | 0.037 | 0.001 | |
| Model 2 | ||||
| Pre-pregnancy BMI | 0.30 | 0.002 | 1.36 | 1.12–1.65 |
| Regular dental care by professional | −0.88 | 0.253 | 0.41 | 0.09–1.88 |
| Excessive weight gain during pregnancy | −2.03 | 0.041 | 0.13 | 0.01–0.92 |
| Constant | −6.32 | 0.020 | 0.002 | |
| Final model | ||||
| Pre-pregnancy BMI | 0.31 | 0.001 | 1.37 | 1.13–1.66 |
| Excessive weight gain during pregnancy | −2.03 | 0.034 | 0.13 | 0.02–0.85 |
| Constant | −7.12 | 0.007 | 0.001 | |
Adjusted OR, adjusted odds ratio; AH, arterial hypertension; B, coefficient; BMI, body mass index; CI, confidence interval.
DISCUSSION
In the present study, we used established methodologies to classify nutritional status and periodontitis during pregnancy; the results obtained indicated that PEW was directly associated with AH and poor periodontal conditions during the third trimester of pregnancy in patients receiving care through a private healthcare system.
Pre-pregnancy maternal overweight status has adverse systemic consequences for pregnancy30. Studies have indicated the associations between overweight status and gestational diabetes mellitus, hypertension, pre-eclampsia, and preterm delivery15., 31., 32., 33.. In this study, the PEW group had a higher frequency of AH (P = 0.019). However, there were no inter-group differences of gestational diabetes mellitus (Table 2).
Hypertension is a multifactorial disease, associated with eating habits, glomerular filtration dysfunction, and metabolic and neuroendocrine disorders. AH is related to vascular inflammation and endothelial disturbance34., 35.. Vascular inflammation involves the release of inflammatory mediators that increase vascular permeability and promote cytoskeletal changes in the endothelial cells; the consequent endothelial dysfunction causes an imbalance between vasodilation and vasoconstriction. Inflammatory mediators, such as CRP, are involved in this process and exacerbate vasoconstriction, thereby causing an increase in blood pressure. This dysfunction is more evident during pregnancy due to the occurrence of physiological, mainly hormonal, changes. These phenomena corroborate the results of our study, as PEW was a significant predictor of AH (adjusted OR = 1.27; 95% CI = 1.03–1.56; P = 0.021; Table 4).
Women with PEW have a larger amount of fat mass but achieve lower weight gain in pregnancy than pregnant women with PNW36. In our study, there was no intergroup difference in the overall absolute weight gain during pregnancy (PEW = 8.77 ± 7.38; PNW = 8.31 ± 3.81); however, women with PEW more often presented a higher level of weight gain during the third trimester than that recommended by the Institute of Medicine (P = 0.010; Table 2). This result can be explained by the eating behaviours of patients: those with excessive weight have inappropriate eating behaviours, which are perpetuated during pregnancy; whereas those with normal weight are typically more concerned about their diet, especially during pregnancy, in order to maintain a healthy gestational period. Diagnosis of excessive weight gain during pregnancy should be done per the Institute of Medicine protocol, which individualises weight gain through cut-off points established according to pre-pregnancy BMI. Therefore, a comparison between groups using absolute values of weight gain during pregnancy should be avoided, as overweight and obese pregnant women are expected to gain less weight, in kg, during the entire gestational period.
Reports have indicated that overweight status of individuals is associated with both lower education level and monthly household income18., 37., 38. and, consequently, with poor oral hygiene behaviours. However, in this study, there were no inter-group differences in the level of education (P = 0.135) and monthly household income (P = 0.086; Table 2), which may be because the study population was recruited from the private healthcare system and reflected a similar socioeconomic level of the participants; moreover, there were no group-wise differences in the oral hygiene behaviours of daily tooth-brushing and use of dental floss. However, patients with PEW used dental services less frequently (P = 0.024; Table 3), which may be because these patients did not consider oral health a priority once affected by several systemic conditions related to being overweight or obese.
In addition to the lack of concern for personal oral health conditions in patients with PEW, overweight status or obesity may be associated with poor periodontal conditions, because the adipose tissue of these individuals secrete inflammatory mediators, such as TNF-α, IL-6 and CRP. These inflammatory mediators increase the host susceptibility to inflammation, which leads to periodontal destruction in the presence of dental plaque39., 40.. Hormonal alterations during gestation are also associated with poor periodontal conditions, as they reduce the patients’ immune response and exacerbate the inflammatory response in the presence of dental plaque.
The PEW group had a higher frequency and severity of periodontitis (P < 0.0001). In contrast, the groups showed no differences in the prevalence of dental calculus (P = 0.166). However, a higher prevalence of sites with BOP (P = 0.005) and a higher frequency of gingivitis, according to the standardised classification (P = 0.0008), were found in the PEW group (Table 3).
In the results of binary logistic regression to determine variables related to the presence of periodontitis during gestation, pre-pregnancy BMI, presence of hypertension, absence of regular dentist attendance, and excessive weight gain during pregnancy were significant variables included in the initial model (Table 5), and variables without significant relevance were removed from the model. Finally, high pre-pregnancy BMI (adjusted OR = 1.37; 95% CI = 1.13–1.66; P = 0.001) and excessive weight gain (adjusted OR = 0.13; 95% CI = 0.02–0.85; P = 0.034) were independent variables remaining in the final logistic model of the presence of periodontitis during pregnancy (Table 5). Therefore, the association of these variables reflected the presence of periodontitis during the third trimester of pregnancy with an accuracy of 86%.
Some previous studies have reported a positive association between excessive weight and periodontitis during pregnancy16., 17., 18., 19., 20., 21.. Nonetheless, these studies used different methodologies for the classification of periodontitis and nutritional status. In this study, a standardised classification for periodontitis from Eke et al.26, and that for nutritional status according to the World Health Organisation23, were adopted.
Our study has some limitations. First, it was a cross-sectional study, and future application of a longitudinal design would enable interpretation related to causal relationships. In addition, because monitoring of participants before pregnancy was not possible, pre-pregnancy weight and BMI were obtained from the patients’ medical records. Due to the retrospective nature of data included in the analyses, variability may have been introduced based on the heterogeneity of medical records and providers. Moreover, there were no absolute levels of control for hypertension and gestational diabetes mellitus, and only the presence/absence of these conditions was collected from the patients’ obstetric records. Finally, because the number of pregnant women with pre-pregnancy obesity was small, overweight and obese patients were included in the same group. Longitudinal studies including a larger sample of only patients with obesity, and recording absolute values related to hypertension and gestational diabetes mellitus, may be needed.
Despite the limitations of the present study, it improves the current level of understanding of the association between PEW and systemic and oral conditions; in addition, previous studies did not standardise methods for classification of periodontitis and nutritional status. Our study supports an integral and multi-professional approach to overall health of pregnant women throughout the gestational period.
CONCLUSION
Women with PEW who underwent follow-up in the private healthcare system had a higher prevalence of AH and worst periodontal status during the third trimester of pregnancy than pregnant women with normal weight.
Acknowledgements
The authors thank the São Paulo Research Foundation (FAPESP; grants 12/10687-0 and 2015/25421-4), National Council for Scientific and Technological Development (CNPq; grant 301578/2016-8), and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior–Brasil (CAPES–Finance Code 001) for providing support for this study. FAPESP, CNPq and CAPES had no role in the study design, data analysis or manuscript drafting/approval.
Conflict of interest
The authors declare that there are no conflicts of interest related to this study.
Authors’ contributions
NSF and GAFJ carried out data collection and analysis, and wrote the paper. ALTM and BGJ carried out data collection and analysis, and assisted in writing the paper. SHCSP conceptualised the study, supervised the project and edited the manuscript.
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