Participants and recruitment
This was the baseline survey of a RCT study which aimed to observe the effects of mouth rinse intervention during pregnancy on reducing the negative pregnancy outcomes such as Premature Rupture of Membranes (PRM), Gestational Diabetes Mellitus (GDM), and Pregnancy-induced Hypertension (PIH) et al [21]. The study was conducted in Maternal and Child Health Hospital of Leping, Jiangxi Province, China, a mid-income rural area with around 20% of the total income from agriculture. The hospital is the only maternal and child health care hospital in the county, with a total of 4,000 deliveries annually, accounting for nearly half of the total deliveries in the county. All pregnant women attending prenatal care visits and meeting the criteria were invited to participate in the study by research nurses [21].
The inclusion criteria of participants were as follows: (1) pregnant women who were at least 18 years old with gestational age less than 20 weeks; (2) having an educational level no less than grade 3 in primary school and with the basic ability to read and write; (3) having at least 20 teeth; (4) having no moderate or severe dental caries; (5) having no systemic disease, including severe cardiovascular disease, diabetes, hyperthyroidism, and/or other systemic diseases; (6) having no sexual transmitted disease; (7) willing to participate in the study and to sign the informed consent form.
Research methods and tools
Written informed consent was obtained from each eligible participant before they were provided with a free dental examination for screening periodontal disease. A self-administered questionnaire was distributed, checked and collected by nurses at the recruitment. Ethical approval to conduct this trial has been granted by the Institutional Review Board of School of Public Health, Fudan University, Shanghai, China (IRB# 2013- 09-0462); and also by the Institutional Review Board of Tulane University, New Orleans, Louisiana, USA (IRB# 13–469160). The original RCT is registered with Chinese Clinical Trial Registry (#ChiCTR-TRC-13003768) [21].
The self-administered questionnaire mainly contained three sections. Section A was about respondents’ demographic characteristics and health related information. Section B collected the information on women’s routine oral health habits, including the frequency of daily tooth brushing, the duration of tooth brushing, the habit of rinsing mouth after meals or snacks, and the approach of brushing teeth. Each of four questions about oral health habits was graded with one score. Pregnant women received 0 for none appropriate to four appropriate for all. According to pre-pregnancy BMI, pregnant women were categorized into underweight (£18.5), normal and overweight/obesity (³25). Section C mainly contained a Chinese version of Edinburgh postpartum depression scale (EPDS). It was a 10-item self-report instrument in which women were asked to rate how they had felt in the previous 7 days. EPDS serves as a ‘gold standard’ for the diagnosis of both Antepartum Depression and Postpartum Depression [22]. Each question of EPDS scores 0–3 and the total score ranges from 0 to 30 [22].The increased EPDS scores indicates a higher possibility of antepartum depression.
Dental examination was performed on pregnant women using Periodontal Screening and Recording (PSR) [23]. PSR, developed by the American Academy of Periodontology, is a simple, safe, inexpensive and rapid screening tool for periodontal disease compared with the full mouth periodontal examination. During the examination, the mouth was divided into sextants. The dentist examined each sextant by using a ball tipped probe with a color-coded area 3.5mm to 5.5mm. During the examination, the dentist inserted the probe into the periodontal pocket, walked around the circumference of each tooth, observed the position of the color-coded band in relation to the gingival margin, and recorded the highest code of the sextant [23-25]. Measurements were recorded in a special box chart with 6 blanks to be filled with 6 codes scored 0-4. Code 0 means healthy periodontal conditions with no bleeding after gentle probing and no calculus or defective margins detected; Code 1 means gingival bleeding, which is with bleeding after gentle probing and no calculus or defective margins detected; Code 2 means gingival bleeding and calculus, which is detection of supragingival or subgingival calculus and/or defective margins; Code 3 means shallow periodontal pockets with a probing depth greater than 3.5mm and not more than 5.5mm, defined as Mild & Moderate Periodontal Disease; Code 4 means deep periodontal pockets with a probing depth greater than 5.5mm, also being defined as Severe Periodontal Disease[23]. Pregnant women were diagnosed with periodontal disease with at least one code higher than 2.
Statistical analyses
Univariate analyses were firstly applied to explore the factors associated with periodontal disease, gingival bleeding or calculus, and severe periodontal disease among pregnant women, respectively. Categorical variables were compared using Pearson χ2 test or Fisher’s exact test; Mann-Whitney U test was used for comparing distributions and trends for non-normal distributed data, and also for ordered categorical variables. Finally, multivariable logistic regression model was used to identify factors associated with periodontal conditions. Adjusted odds ratios (aOR) and 95% confidence interval (CI) were derived from the coefficients of the logistic models and their standard errors. The multiple linear regression model was used to test the trend for severity of periodontal disease among pregnant women and risk factors. The severity of periodontal disease was set as an ordinal variable, being coded from one to three representing healthy periodontium, mild/moderate periodontal disease, and severe periodontal disease, respectively. All statistical analyses were performed using SPSS software (SPSS for Windows version 21.0; SPSS Inc., Chicago, IL).