Development Of The Chinese Pregnant Women’s Dietary Inflammatory Index And Its Association With Gestational Diabetes Mellitus Risk In A Cohort Study

backgroundRecent evidence indicates that chronic low-grade inflammation plays an essential role in the pathogenesis of chronic non-communicable diseases,and diet can moderate systemic inflammation.Recently,there have been increasing studies on evaluating the overall inflammatory effects of diet by using the dietary inflammatory index（DII）,which was proposed to comprehensively assess the anti-inflammatory and pro-inflammatory effects of an individual’s diet.However,DII use among Chinese pregnant women is limited because of this current index“global”database.For example,the world standard database used for the DII includes data on dietary parameters only from adults and mainly from western countries.In addition,not all the parameters that comprise the DII（e.g.,alcohol or coffee intake）are appropriate to include when evaluating pregnant women’s dietary quality.So it is limited for use in evaluating food inflammatory in Chinese pregnant women.Furthermore,only a few have evaluated the link between DII and GDM,and the findings were conflicting.With those backgrounds in mind,our objectives in the current study were to develop and validate a literature-derived Chinese pregnant women’s dietary inflammatory index（CPW-DII）,and investigate the association between CPW-DII and GDM risk in a Chinese prospective cohort study.Objectives（1）To evaluate the inflammatory potential of whole diets in Chinese pregnant women’s dietary inflammatory index（CPW-DII）.（2）Information regarding the possible relationship between diet-related inflammation and the risk of GDM is limited.The second aim of the present study is to investigate the association between the inflammatory potential of the diet,measured by CPW-DII,and GDM risk in a Chinese prospective cohort study.Methods（1）Development and validation of CPW-DIIDietary data were obtained from Chinese pregnant women based on an extensive literature review and created a reference database for computing CPW-DII scores.The Medline/Pub Med,Embase,Cochrane,Web of Science,China National Knowledge Infrastructure（CNKI）,and Wanfang were searched between 2010 and 2019.Mean dietary intakes and corresponding 95%confidence interval were estimated using random-effects models.To develop the CPW-DII,methods similar to those used to develop the current version of the dietary inflammatory index（DII）were employed.Using the“inflammatory effect scores”and score algorithm described in the development of the DII,we develop the CPW-DII.The CPW-DII was then validated in a representative subsample of 536 pregnant women who participated in Tongji Maternal and Child Health Cohort（TMCHC）from March 2018 to December 2019,and blood was drawn around the same time as food frequency questionnaire（FFQ）administration between the 13th to 28th week of pregnancy.We used a self-administered questionnaire to obtain data on each pregnant woman’s demographic information,socioeconomic status,disease history,lifestyle,and dietary habits at enrollment.Dietary intake was obtained using a validated semi-quantitative FFQ and calculated the CPW-DII scores as described above.ELISA measured C-reactive protein（CRP）concentration.CRP was log-transformed in order to normalize the distribution.Correlations between CPW-DII and CRP concentrations were measured by using the partial correlation coefficient.Multivariate linear regression was conducted to examine the association between CPW-DII score and CPR.（2）The association between CPW-DII and GDM riskWe also included 4189 eligible women from TMCHC to evaluate the association between CPW-DII and GDM risk.Dietary intake was assessed during gestational weeks13-28 and before GDM diagnosis（13th to 28th week of pregnancy）and was used to calculate the CPW-DII scores described in part one.Multivariable-adjusted logistic regression models were performed to estimate the association between CPW-DII and GDM risk,modeled continuously and quartiles.We conducted analyses stratified by age（<30 years or≥30 years）,pre-pregnancy BMI（<24.0 kg/m²or≥24.0 kg/m²）,family history of diabetes（Yes/No）,parity（Yes/No）to explore the potential modification effects of specific covariates on the association between CPW-DII scores and GDM risk.The Wald test was used to test the potential effect modification by adding these covariates with CPW-DII.Results（1）Development and validation of CPW-DIIA total of 29 studies（including 47245 participants）with a sample size of over 200were identified from an extensive literature search to represent a range of Chinese pregnant women’s dietary intakes during pregnancy.According to the dietary parameters included in the DII,combined with the actual situation of Chinese pregnant women’s dietary intake during pregnancy and literature search results,a database containing 27parameters was constructed.The parameters used to calculate CPW-DII were:energy,carbohydrate,protein,fat,cholesterol,saturated fatty acids,monounsaturated fatty acid,polyunsaturated fatty acid（PUFA）,n-3 PUFA,n-6 PUFA,fiber,folic acid,vitamin A,vitamin C,vitamin D,vitamin E,thiamin,riboflavin,niacin,vitamin B6,vitamin B12,β-carotene,Fe,Zn,Se,Mg,and isoflavone.Then referring to“inflammatory effect scores”and score algorithm used to compute DII scores,and relying on the database of Chinese pregnant women’s dietary intake during pregnancy,the calculation method of CPW-DII was constructed.The average CPW-DII score of 536 pregnant women was 0.28±1.32,and the average CRP concentration was 3.14±2.40 mg/L.There was a negative correlation between CPW-DII and intakes of fiber and vitamins（known for having an anti-inflammatory effect）（P≤0.001）,and a positive correlation between CPW-DII and intakes of energy,carbohydrate,total fat,and saturated fatty acids（known for having a pro-inflammatory effect）（P≤0.001）.Additionally,the CPW-DII was also successfully validated with blood CRP concentrations.A significant and positive association between the CPW-DII scores and CRP concentrations was identified after adjustment for maternal age,pre-pregnancy that the CRP concentration increased 0.08 mg/L（95%CI:0.00,0.16）for each SD increase of the CPW-DII score after adjustment for maternal age,pre-pregnancy BMI,smoking,drinking,and gestational age at sampling.There was also a significant and positive association between CPW-DII scores and CRP concentrations after adjustment for confounding factors(β:0.20;95%CI:0.02,0.38,P _trend=0.033)for the third tertile vs.the first tertile.（2）The association between CPW-DII and GDM riskA total of 4189 eligible pregnant women were included in analyzing the association between CPW-DII and the risk of GDM.The mean CPW-DII score and the corresponding SD were 0.12±1.43 with a range of-4.61 to 4.14 during the second trimester of gestation,and 470 GDM cases were identified,the incidence rate of 11.2%（95%CI:10.3%,12.2%）.Women with GDM were more likely to have higher CPW-DII scores than those without GDM（0.26 vs.0.10）.A significant and positive association between the CPW-DII score and the incidence of GDM was identified in the crude model and fully adjusted models.Covariates in multivariable models included maternal age,pre-pregnancy BMI,education level,average personal income,family history of diabetes,smoking and drinking,parity,pregnancy exercise,multivitamin supplement use,and total energy intake.Adjusted for potential confounding factors yielded slightly attenuated but significant results,the odds ratio（ORs）with 95%confidence interval（CIs）for GDM were 1.10（0.80,1.51）,1.54（1.14,2.08）,1.38（1.01,1.87）for successive quartiles of CPW-DII score,respectively(P _trend=0.009),comparing with the lowest quartile.After adjusted for potential confounding factors,the risk of GDM increased by 12%（95%CI:1.01,1.24）with an SD increment in CPW-DII score.Stratified analyses were performed to assess the potential effect modification for the association between CPW-DII and GDM risk.The association between CPW-DII and GDM risk was not significantly modified by pre-pregnancy BMI,parity,and family history of diabetes（all P for interactions were>0.05）.The association between CPW-DII score and risk of GDM was stronger among pregnant women whose age<30 years（OR:1.94;95%CI:1.28,2.95）.Conclusions（1）We develop a novel literature-derived dietary pattern adapted to Chinese pregnant women’s diet characteristics to assess diet quality based on its inflammatory potential.Results indicated that the CPW-DII was significantly associated with inflammatory biomarker among Chinese pregnant women in TMCHC,which indicates its reliability in assessing Chinese pregnant women’s overall dietary inflammatory potential during pregnancy.Further validation with other inflammatory markers is required to deepen the relationship between the CPW-DII and inflammation markers in Chinese pregnant women.（2）This prospective cohort study indicated that a higher CPW-DII score,corresponding to a more pro-inflammatory diet,is associated with a higher risk of GDM.Hence,avoiding a pro-inflammatory diet during pregnancy could be attractive targets for prevention strategies and dietary guidance to prevent GDM.