The Fetal Growth Curve And The Effects Of Maternal Behavioral Exposure During Periconception Period For Twins

Background & Objective: The rate of twin pregnancies has continued to increase worldwide,however,until now the clinical prenatal examination for the intrauterine growth of twins still largely relies on the growth standards of singletons.This study was aimed to conduct twin-based cohort study to establish a set of fetal biometric parameter references for Chinese twin pregnancies using ultrasonographic data,and furthermore,to explore the association of maternal behavioral exposure during periconception period with birth outcomes of the offspring.Methods: All twin pregnant women who first visited the specialist outpatient department of twins of International Peace Maternity & Child Health Hospital during November 15,2018 to January 20,2020 were recruited to establish a prospective cohort study.Follow-up investigation was conducted on pregnant women using the unified questionnaire.The questionnaire covers the following information,such as maternal sleep,diet and physical activities during periconception period,the basic information,healthy condition and the other environmental and behavioral exposure of parents.The data of ultrasonographic fetal biometric parameters was obtained from the information department of this hospital.To ensure the smoothness and accuracy of the fitting intrauterine growth curve,all twin pregnancies who delivered in the same hospital during January 1,2016,to January 20,2020 was added when fitting growth curve.The ultrasonographic fetal biometric parameters were longitudinally measured from 14 to 37 week of gestation,including estimated fetal weight(EFW),biparietal diameter,head circumference,abdominal circumference,femur length(FL)and humerus length(HL).Birth outcomes were collected including delivery mode,gestational age,gender,Apgar score,birth weight and birth length.Statistical description was made to describe the sample characteristics.The comparison was performed using paired Chi-square test,paired t-test,or Wilcoxon ranksum test of correlated samples between two groups,and Chi-squared test or variance analysis or Kruskal-Wallis rank test between three groups.The growth curve of each biometric parameter was modeled by generalized additive model for location scale and shape.The linear mixed models were used to test the difference of growth pattern between groups.The multivariate analyzes between maternal behavioral exposure and birth outcomes were carried out on using log-binomial regression and multiple linear regression model.Results: A total of 281 twin pregnant women were included,of which 224 had completed delivery.In addition,a total of 1118 women,188 spontaneously conceived monochorionic diamniotic(SC-MCDA)vs.263 spontaneously conceived dichorionic diamniotic(SC-DCDA)vs.667 assisted reproductive technology dichorionic diamniotic(ART-DCDA)twins,were included to fit intrauterine growth curve.The comparison results of growth trajectories between groups showed that all the fetal biometric parameters of SC-DCDA twins were higher than those of SC-MCDA twins(p<0.05),and the growth velocity for EFW,biparietal diameter,head circumference,FL and HL was statistically different between both(p<0.05).The weekspecific differences for fetal biometric parameters between SC-MCDA and SC-DCDA twins were found at 15,21-22,25 and 33 weeks of gestation.ART-DCDA twins were different from SC-DCDA in the fetal biometric parameter curves for EFW,abdominal circumference,FL and HL and the growth velocity for EFW and FL(all p<0.05).The result of multivariate analysis demonstrated that maternal poor sleep quality during the first trimester were significantly associated with the reduced birth weight(β=-155.20 g,95% CI: 28.53 ～ 281.87)and the increased risk of premature birth(RR:1.237,95%CI: 1.007～1.519)and low birth weight(RR:1.310,95%CI:1.036 ～ 1.658),tmaternal sleep disordered breathing during the first trimester can significantly decrease the gestational week of delievry(β=-0.96 weeks,95% CI: 0.24 ～ 1.68).Moreover,more intake of both the staple food and food with stuffing during periconception period was associated with lower risk of twin discordancy(The staple food: progestation: RR: 0.915,95%CI: 0.844～0.992;Food with stuffing: progestation: RR:0.699,95%CI: 0.515～0.949,early pregnancy: RR: 0.765,95%CI: 0.610～0.960),and progestational intake of coarse food grains/potatoes was associated with the increaseed gestational week of delivery(β=0.14 weeks,95%CI: 0.06～0.23)and decreased risk of premature birth(RR: 0.939,95%CI: 0.900～0.981).More periconceptional intake of eggs and dairy and bean product were related with higher birth weight(Eggs and dairy: progestation: β=21.16 g,95%CI:4.54～37.78,early pregnancy: β=16.89 g,95%CI: 1.90～31.88;Bean product: β=35.70 g,95%CI: 0.21～71.19)and lower risk of low birth weight(Early pregnancy:eggs and dairy:RR: 0.957,95%CI: 0.927～0.987;bean product: RR: 0.913,95%CI: 0.841～0.992),the dessert intake in early pregnancy was positively associated with gestational age(β=0.18 weeks,95%CI:0.05～0.30),birth weight(β=39.49 g,95%CI: 7.10～71.89)and birth length(β=0.31 cm,95%CI: 0.11～0.51),and the processed/fried food intake in early pregnancy was positively associated with birth length(β=0.16 cm,95%CI: 0.01～0.31).Progestational intake of eggs and dairy was associated with the increaseed gestational week of delivery(β=0.12 weeks,95%CI: 0.06～0.18),and progestational folic acid supplementation use was respectively related with higher birth weight(β=118.08 g,95%CI: 15.81～220.35)and bigger gestational week of delivery(β=0.49 weeks,95%CI:0.10～0.88).Furthermore,more physical activity in early pregnancy was associated with higher birth weight(β=7.56 g,95%CI: 0.50～14.63)and lower risk of premature birth(RR:0.978,95%CI: 0.962～0.994)and low birth weight(RR: 0.979,95%CI: 0.961～0.997).Conclusion: We are the first to establish fetal biometric reference values for Chinese SC-MCDA,SC-DCDA and ART-DCDA twin pregnancies.The growth pattern of SCDCDA twins was different from that of SC-MCDA and ART-DCDA twins.Maternal poor sleep quality and sleep disordered breathing in early pregnancy was associated with increased risk of premature birth and low birth weight and decreased gestational age at birth,respectively.Among periconceptional behavioral exposures,the intake of coarse food grains/potatoes,eggs and dairy and dessert and folic acid supplementation use was positively associated with gestational age,intake of the eggs and dairy,bean product and dessert and folic acid supplementation use respectively related with birth weight,and the dessert and processed/fried food intake in early pregnancy was positively associated with birth length.The intake of coarse food grains/potatoes and folic acid supplementation use in early pregnancy respectively related with decreased risk of premature birth,more periconceptional intake of the staple food and food with stuffing were associated with lower risk of twin discordancy,and both the eggs and dairy and bean product intake in early pregnancy were associated with decreased risk of low birth weight.In addition,more physical activity in early pregnancy was related with lower risk of premature birth and low birth weight.