| Background:The key period of infant brain development is from the beginning of pregnancy to two years after birth.Iodine deficiency of pregnant and lactating women will cause serious harm to the health of offspring.In recent years,there are few studies on the iodine nutritional status of lactating women and infants in China,and there is a lack of relevant research data.After the decrease of the iodine content in table salt,it is not clear whether the iodine nutritional status of lactating women and infants in China is still in an appropriate state and whether the proportion of individual iodine deficiency is increasing.Purpose:To understand the iodine nutritional status of lactating women and infants in Lingang area of Shanghai,and to explore the relationship between dietary iodine intake,urine iodine,breast milk iodine of lactating women and urine iodine,TSH of infant.To supply the data of iodine for lactating women and infants in Lingang area of Shanghai,and to provide reference data for the establishment of iodine suitable standard for special population in China.Contents and methods:This study was carried out in the Shanghai Sixth People's Hospital East campus from May 2018 to April 2019.The subjects were pregnant women who had regular routine examination in the outpatient department of gynecology and Obstetrics?traced to 42-day after delivery?.According to the inclusion exclusion criteria,the pregnant women in the group were guaranteed to meet the screening criteria.Record basic information and sign informed consent with it.?1?During the 14?16 weeks and 34?36 weeks of gestation,3 m L of fasting venous blood was collected by the medical staff once respectively.The levels of free thyroxine?FT4?,free triiodothyronine?FT3?,thyroid stimulating hormone?TSH?,thyroglobulin?Tg?,thyroglobulin antibody?Tg Ab?and thyroid peroxidase antibody?TPOAb?weredetermined by electrochemiluminescence.?2?Three days after delivery,the heel blood of the newborn was collected by medical staff and made into dried blood spot?DBS?.The TSH of the newborn was determined by time-resolved immunofluorescence analysis?TR-FIA?.?3?On the day of 42-day postpartum examination,10 m L urine of lactating women and their infants were collected,10 m L breast milk of lactating women was collected,and urinary iodine and milk iodine were determined by inductively coupled plasma mass spectrometry.At the same time,the 24-hour dietary status,dietary types?including drinking water,iodized salt and nutritional supplements?and intake of lactating women on the day before urine samples collection were collected via 24-hour dietary recall.After that,the data will be entered into the Zending nutrition star?advanced version?application,and the software will automatically generate the individual daily iodine intake.To evaluate the iodine nutritional status of lactating women and infant by measuring breast milk iodine concentration?BMIC?,urinary iodine concentration?UIC?,dietary iodine intake and TSH,to explore the relationship among lactating women's UIC,BMIC and infantile UIC,and to explore the effects of urine iodine level,diet and TSH level of late pregnancy on their own iodine nutrition and the iodine nutrition,TSH,growth and development of their offspring.Results:?1?The MUIC of lactating women in Lingang area of Shanghai was110.0?g/L?IQR 65.8,171.4?.44.5%of lactating women had UIC<100?g/L,which was in iodine deficiency state.The MBMIC of lactating women was 150.7?g/L?IQR 102.9,205.5?,23.4%of lactating women had BMIC<100?g/L,49.3%of lactating women had BMIC at 100?199?g/L.The median dietary iodine intake of lactating women was 152.3?g/L?IQR 136.0,170.1?.Among the lactating women,86.1%?n=198?ate iodized salt,13.5%?n=31?ate non-iodized salt and 0.4%?n=1?ate mixed salt.The mean levels of TSH in early and late pregnancy were 1.7±0.9 m IU/L and 2.5±1.2 m IU/L,respectively.?2?The MUIC of infant population was 212.7?g/L?IQR 142.1,320.6?,10.0%of infants had UIC<100?g/L,which was in iodine deficiency state.The median TSH of newborn was 1.5 m IU/L?IQR 1.0,2.3?,which was in the normal range of 0.00?9.00m IU/L.?3?There was a positive correlation among lactating women's UIC,BMIC and infantile UIC(r=0.597**,P<0.001)?r=0.182*,P=0.01?(r=0.373**,P<0.001).The highest UIC was found in infants,the second in BMIC and the lowest in mother's UIC,with statistical significance?P<0.001?.There was a positive correlation between dietary iodine intake and BMIC of lactating women?r=0.216*,P=0.014?.There was a positive correlation between dietary iodine intake and UIC of exclusively breastfed infants?r=0.205*,P=0.024?.There was no significant correlation between dietary iodine intake and UIC of self?r=0.038,P=0.659??There was a positive correlation between maternal TSH in early pregnancy and BMIC?r=0.193*,P=0.008?,infantile TSH(r=0.193**,P=0.008),but no significant correlation between maternal TSH in early pregnancy and their UIC?r=-0.11,P=0.876?,infantile UIC?r=0.48,P=0.51?.There was a positive correlation between maternal TSH level in the third trimester and infant TSH level?r=0.179*,P=0.013?;there was no significant correlation between maternal TSH level in the third trimester and their UIC?r=0.001,P=0.993?,BMIC?r=0.046,P=0.526?,infant UIC?r=-0.005,P=0.944?.?4?The MBMIC of iodine deficiency group was 118.4?g/L?IQR 70.6,172.9?,iodine appropriate group was157.6?g/L?IQR 129.3,206.0?.The BMIC of iodine appropriate group was higher than that of iodine deficiency group,and the difference between BMIC of different urinary iodine levels was statistically significant?P=0.000?.The infantile MUIC of iodine deficiency group was 192.0?g/L?IQR 125.2,259.3?,iodine appropriate group was 230.7?g/L?IQR 171.5,395.3?.The infantile UIC of iodine appropriate group was higher than that of iodine deficiency group,and the difference between infantile UIC of different urinary iodine levels was statistically significant?P=0.048?.There was no significant difference between the different urinary iodine levels of dietary iodine intake,infantile TSH level and 42d weight of infants?P=0.110,P=0.192,P=0.366?.?5?There were significant differences in infantile UIC level?P=0.000?,lactating women's UIC level?P=0.001?and dietary iodine intake?P=0.004?among different milk iodine groups.There was no significant difference between TSH level and 42d weight of infantswith different milk iodine levels?P=0.901,P=0.365?.?6?The median dietary iodine intake of the non-iodized salt group and the iodized salt group was 31.5?g/L?IQR 17.8,42.2?and 155.9?g/L?IQR 139.8,172.4?,respectively,with statistical significance?P<0.001?;the MBMIC of the non-iodized salt group and the iodized salt group was 111.9?g/L?IQR 68.7162.8?and 156.8?g/L?IQR 115.8,208.8?,respectively,with statistical significance?P=0.015?.There was no significant difference in lactating women's UIC?P=0.307?,infantile UIC?P=0.250?,infantile TSH?P=0.864?and infantile 42d weight?P=0.948?between non iodized group and iodized group.?7?The median TSH of newborn was 1.5 m IU/L?IQR 1.0,2.1?in the group with TSH<4m IU/L in the late pregnancy.The median TSH of newborn was 2.2 m IU/L?IQR1.4,3.3?in the group with TSH>4m IU/L in the late pregnancy.The TSH level of infants in the TSH<4 m IU/L group was lower than that in the TSH>4 m IU/L group?P=0.031?.There was no significant difference in lactating women's UIC,BMIC,dietary iodine intake,infantile UIC,birth weight,42d weight between TSH<4m IU/L group and TSH>4m IU/L group.Conclusion:?1?According to the evaluation standard of iodine nutritional status recommended by the World Health Organization?WHO?,iodine is suitable for lactating women and infants in Shanghai.?2?For individuals,44.5%of lactating women lack iodine,which is worthy of attention.Lactating women have the risk of iodine deficiency.?3?Iodized salt can increase the breast milk iodine concentration.?4?The level of infantile urinary iodine was positively correlated with the level of urinary iodine and breast milk iodine of the mother.?5?Maternal TSH level during pregnancy is positively correlated with neonatal TSH level,and maternal TSH abnormality in late pregnancy increases the risk of offspring TSH elevation. |
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