| Objective:The aim of this study was to explore the relationship among "maternal nutritional intake and environmental factors-IGF2 DNA methylation patterns in offsprings-birth characteristics", and to provide important clues for cancer prevention and nutritional intervention.Methods:1. Selection of subjectsPregnant women, without medical conditions such as diabetes, hepatitis infection or other coeliac diseases, and came to the hospital for delivery between April and September 2008, were considered eligible for the study. The total of 99 mothers participated in this study after being informed the purpose and significance of this study.2. Determination of one-carbon nutrients in serumSerum folate and vitamin B12 were determined using paramagnetic particle chemiluminescent immunoassay method. Serum zinc was determined using Atomic absorption spectrophotometry.3. The determination of IGF2 DNA methylation statusMethylation patterns of IGF2 were analyzed by Real time-PCR.4. Measurement of birth characteristicsThe body weight of offspring was weighed by electronic scale. The head circumference and the birth length of offspring were measured using horizontal length meter.5. Data management and statistical analysisAll analyses were performed using the SPSS 12.0. Major methods included paired sample T-test, multiple linear regression analysis and so on. A P-value of less than 0.05 was considered statistically significant.Results:1. The association between birth characteristics with nutrient content of maternal serum and maternal environmental exposures during pregnancy.(1) The mean level of serum folate was 2.29ng/ml for maternal and 7.29ng/ml for offsprings respectively. The mean level of serum vitamin B12 was 175.34pg/ml for maternal and 240.19pg/ml for offsprings respectively. The mean level of serum zinc was 0.67μg/ml for maternal and 0.93μg/ml for offsprings respectively. Serum folate levels (t=-12.183,P=0.001), vitamin B,2 levels (t=-4.432,P=0.001)and zinc levels (t=-5.551,P=0.001) in cord blood were significantly higher than in mother's blood respectively. Serum folate levels (r=0.367, P=0.001) and vitamin B12 levels (r=0.325, P=0.001) in cord blood were correlated with mother's blood respectively. Similar correlation, however, was not observed for zinc.(2) The average birth length of offspring was 49.48cm, the average weight was 3.19kg and the average head circumference was 33.83cm. Birth weight, length and head circumference of offsprings was related with pre-pregnancy body mass index of maternal respectively (β=0.237, P=0.020;β=0.373,P=0.001;β=0.251, P=0.015).(3) Birth weight and head circumference of offsprings were related with sex of newborn respectively (β=-0.292, P=0.004;β=-0.217, P=0.036).(4) Birth length of offsprings was related with maternal cesarean (β=0.210, P=0.034).2. The association between serum nutrient content of maternal and offspring and maternal environmental exposures during pregnancy with IGF2 DNA methylation pattern.(1) The mean percentages of methylation in P2 promoter were 2.84% for mother's blood and 3.94% for cord blood respectively. The percentages of methylation in P3 were 5.83% for mother's blood and 4.11% for cord blood respectively. The percentage of methylation in P2 in cord blood was significantly higher than in mother's blood (t=-2.724, P=0.008), but uncorrelated with each other. The percentage of methylation in P3 in mother's blood was significantly higher than that in cord blood (t=4.376, P=0.001), and significantly correlated with each other (β=0.403, P=0.001).(2) IGF2 P2 DNA methylation status of offsprings was related with maternal cesarean (β=0.287, P=0.006). IGF2 P3 DNA methylation status of offsprings was related with maternal serum vitamin B12 (β=-0.279, P=0.004) and education level of mothers (β=0.213,P=0.030).(3) IGF2 P2 DNA methylation status of maternal was related with maternal serum vitamin B12 (β=-0.231, P=0.020), weight gain during pregnancy (β=0.229,P=0.023) and passive smoking (β=0.231, P=0.020). IGF2 P3 DNA methylation status of maternal was related with maternal serum zinc (β=-0.234,P=0.022) and education level of mothers (β=-0.290,P=0.005).3. The significant correlation between IGF2 DNA methylation pattern of maternal and offsprings was not found.Conclusions:1. Maternal pre-pregnancy body mass index and cesarean may be associated with birth characteristics of offsprings.2. Exposure to passive smoking during pregnancy and maternal serum vitamin B12 may be associated with IGF2 methylation status of maternal and offsprings.3. IGF2 methylation status of maternal and offsprings may not be associated with birth characteristics of offsprings. |
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