Effects Of Dairy Consumption During Pregnancy On Maternal Obesity-Related Outcomes And Birth Outcomes: A Prospective Study

Objective: It has been reported that the consumption of dairy products during pregnancy has an impact on gestational obesity and birth outcomes;however,the conclusions of these previous researches are in conflict.In addition,a study based on the Chinese population needs to be conducted because most of the previous research settings are heterogeneous to China.Therefore,this study aimed to describe the dairy products consumption during pregnancy of the mothers from Northeast Birth Cohort,and further study the effects of maternal consumption of dairy products during pregnancy on maternal obesity-related outcomes and birth outcomes.Methods: Pregnant women of 24-28 weeks were recruited to the Northeast Birth Cohort in obstetric clinic,Shengjing Hospital of China Medical University,from December 2018 to June 2020.At the time of enrollment,sociodemographic data,life styles,mental state,as well as pre-conceptional and conceptional food frequency were collected through a baseline questionnaire.At 32 gestational weeks,food frequency,life styles,and other information in the third trimester were collected using a follow-up questionnaire.Moreover,body weight and body fat(BF)were measured by body composition analyzer.Total cholesterol(TC),triglyceride(TG),low-density lipoprotein(LDL),and high-density lipoprotein(HDL)were measured by venous blood test.Gestational weight gain rate(GWGr)was defined as the difference in body weight divided by the difference in gestational week.Birth information including birth weight(BW)and gestational age(GA)were obtained through the Hospital Information System.The exposures were obtained using Food Frequency Questionnaire and 4-day 24-hour Weighed Food Records.The time of exposure included second trimester,third trimester,and second to third trimester of pregnancy.The specific exposures included total dairy products,whole milk,low-fat milk,cheese,yogurt,dairy protein,dairy fat,and dairy calcium.Multiple linear regression model was used to fit the relationships between the dairy products consumption during pregnancy and the GWGr,BF,TC,TG,LDL,HDL,BW and GA.Binary and multinomial Logistic regression model was used to fit the relationship between the dairy products consumption quartiles(Q1,Q2,Q3 and Q4)and preterm birth,HBW,LBW,LGA,and SGA.Three models were used for multivariate analysis: Model 1included the statistically significant variables in the first part analysis;Model 2 and Model 3 included the adjusted variables of Model 1,in addition,the "dietary pattern" and "nutrient pattern" extracted from factor analysis were added to Model 2 and Model 3,respectively.All statistical analyses were performed by SAS 9.4.Results:(1)A total of 2385 pregnant women at 25.4 weeks were included.The median intake of dairy products during pregnancy was 192.3 g,and the main types of dairy products were whole milk and yogurt.The study participants consumed 49.5 g more dairy products during pregnancy than pre-pregnancy.The dairy protein,dairy fat and dairy calcium were all more than those during pre-pregnancy,but only dairy calcium increased by 2.4 mg/kcal after energy adjustment.Dietary patterns changed significantly during pregnancy compared to pre-pregnancy.The factor loads of dairy products varied in different dietary patterns,and they were more associated with "healthy" dietary patterns.In addition,the variables associated with dairy products consumption included occupation,education,sleep quality and so on.(2)A total of 1445 pregnant women were included in the analysis.Multiple linear regression analysis showed that whole milk intake in the second trimester was significantly associated with the increase of LDL(β =0.0007,P = 0.0494);Low-fat milk intake in the second trimester was significantly associated with the decreased HDL(β =-0.0006,P = 0.0051);Stratified analysis showed that there was no significant association between whole milk intake in the second trimester and LDL level in the both subgroups with total dairy intake <300 g and ≥300 g(P > 0.05);The association between low-fat milk intake in the second trimester and HDL level was significant only in the subgroup with dairy intake <300 g(P < 0.0001).(3)A total of 1210 pregnant women and their offspring were included in the analysis.Multivariate analysis on birth weight found that low-fat milk intake in late pregnancy was associated with a decrease in birth weight(β =-0.5240,P = 0.0315);The change of yogurt intake from the second to the third trimester could decrease birth weight(β =-0.5287,P = 0.0500).The relative risk(RR)value of the relationship between dairy protein intake(Q3 vs.Q1)and HBW risk was 0.386,and its 95% confidence interval(CI)was(0.162,0.856);The RR value of the relationship between dairy calcium intake in the second trimester(Q3 vs.Q1)and HBW risk was 0.386,its 95%CI was(0.162,0.869).The RR value and its 95%CI between the increase of yogurt intake from the second to the third trimester(Q4 vs.Q1)and LBW risk was 4.206(1.349,15.447).The RR value and 95%CI between the change of dairy calcium intake(Q3 vs.Q1)and LBW risk was2.912(1.013,9.459).Multivariate analysis on gestational age found that low-fat milk intake in late pregnancy associated with reduced gestational age(β =-0.0017,P =0.0118);In the second trimester,Q4 group of total dairy intake had a 3.176-fold higher risk of preterm birth than Q1 group(95%CI: 1.123,10.488);The risk of preterm birth in Q4 group of dairy calcium intake was 3.092 times higher than that in Q1 group(95%CI:1.090,10.229).Multivariate analysis on SGA and LGA showed that the RR value and95%CI of dairy protein intake in the second trimester(Q3 vs.Q1)and LGA risk was0.418(0.215,0.787).The RR of milk fat intake in late pregnancy(Q3 vs.Q1)and SGA risk was 2.122,its 95%CI was(1.048,4.444).The RR of yogurt intake in late pregnancy(Q4 vs.Q1)and LGA risk was 0.537,its 95%CI was(0.290,0.994).The RR of SGA with the increase in total dairy intake from the second to the third trimester(Q4 vs.Q1)was 2.460,95%CI was(1.081,5.842);The RR of dairy protein intake increase(Q4 vs.Q1)and SGA risk was 2.779,95%CI was(1.193,6.808);The RR of dairy fat intake increase(Q4 vs.Q1)and SGA risk was 3.959,95%CI was(1.611,10.660);The RR of dairy calcium intake increase(Q4 vs.Q1)and SGA risk was 3.017,95%CI was(1.287,7.444);The RR value of yogurt intake increase(Q4 vs.Q1)and LGA risk was 0.478,95%CI was(0.268,0.839).Conclusion:(1)The consumption of total dairy products during pregnancy increased,but it did not meet the recommended level of dietary guidelines.Dairy products,such as yogurt,was important components of "healthy" dietary patterns.(2)In general,the intake of dairy products during pregnancy showed a neutral effect on the GWGr,BF and blood lipids.However,the whole milk consumed in the second trimester might increase LDL,while the low-fat milk might decrease HDL.These adverse effects on blood lipids might be due to the persistently low total dairy intake among the pregnant women.(3)The consumption of dairy products during pregnancy generally showed a decreasing effect on BW and GA.However,only low-fat milk was found to have a significant effect on gestational age in those who met the recommended criteria.(4)The present findings suggested that consumption of dairy products in the second and third trimesters may not make a significant difference on the study maternal and birth outcomes.Furthermore,it was important to pay attention to the individual role of low-fat milk,whole milk,cheese,and yogurt when choosing dairy products during pregnancy.(5)In conclusion,the adverse effect of dairy intake during pregnancy on blood lipid and the down-regulation effect on birth weight and gestational age might be related to the insufficient intake of total dairy products during pregnancy.Therefore,it may be urgent to increase the total intake of dairy products during pregnancy to meet the recommended level of dietary guideline.