Study: NCT03651934

Intervention type: DIETARY_SUPPLEMENT
Group type: EXPERIMENTAL
Intervention: Normal iron
Description: The intervention was divided into two stages, the first stage lasted for 4 weeks, and the dosage used was the dietary nutrient recommendation amount, namely the dietary recommendation amount standard for early pregnancy (iron 20mg/d), and the middle stage of pregnancy (iron 24mg/d). The second stage lasts for 4 weeks. For subjects in iron deficiency, the maximum tolerable amount (iron 42mg/d) is used for intervention. For those with good nutritional status, the dietary recommendation amount is maintained.

Intervention type: DIETARY_SUPPLEMENT
Group type: EXPERIMENTAL
Intervention: Weak iron
Description: The intervention was divided into two stages, the first stage lasted for 4 weeks, and the dosage used was the dietary nutrient recommendation amount, namely the dietary recommendation amount standard for early pregnancy (iron 20mg/d), and the middle stage of pregnancy (iron 24mg/d). The second stage lasts for 4 weeks. For subjects in iron deficiency, the maximum tolerable amount (iron 42mg/d) is used for intervention. For those with good nutritional status, the dietary recommendation amount is maintained.

Intervention type: DIETARY_SUPPLEMENT
Group type: EXPERIMENTAL
Intervention: Weak iron
Description: The intervention was divided into two stages, the first stage lasted for 4 weeks, and the dosage used was the dietary nutrient recommendation amount, namely the dietary recommendation amount standard for early pregnancy (iron 20mg/d), and the middle stage of pregnancy (iron 24mg/d). The second stage lasts for 4 weeks. For subjects in iron deficiency, the maximum tolerable amount (iron 42mg/d) is used for intervention. For those with good nutritional status, the dietary recommendation amount is maintained.

Intervention type: DIETARY_SUPPLEMENT
Group type: EXPERIMENTAL
Intervention: Normal selenium
Description: The intervention was divided into two stages, the first stage lasted for 4 weeks, and the dosage used was the dietary nutrient recommendation amount, namely the dietary recommendation amount standard for early pregnancy (selenium 60ug/d), and the middle stage of pregnancy (selenium 65ug/d). The second stage lasts for 4 weeks. For subjects in selenium deficiency, the maximum tolerable amount (selenium 400ug/d) is used for intervention. For those with good nutritional status, the dietary recommendation amount is maintained.

Intervention type: DIETARY_SUPPLEMENT
Group type: EXPERIMENTAL
Intervention: Normal selenium
Description: The intervention was divided into two stages, the first stage lasted for 4 weeks, and the dosage used was the dietary nutrient recommendation amount, namely the dietary recommendation amount standard for early pregnancy (selenium 60ug/d), and the middle stage of pregnancy (selenium 65ug/d). The second stage lasts for 4 weeks. For subjects in selenium deficiency, the maximum tolerable amount (selenium 400ug/d) is used for intervention. For those with good nutritional status, the dietary recommendation amount is maintained.

Intervention type: DIETARY_SUPPLEMENT
Group type: EXPERIMENTAL
Intervention: Weak selenium
Description: The intervention was divided into two stages, the first stage lasted for 4 weeks, and the dosage used was the dietary nutrient recommendation amount, namely the dietary recommendation amount standard for early pregnancy (selenium 60ug/d), and the middle stage of pregnancy (selenium 65ug/d). The second stage lasts for 4 weeks. For subjects in selenium deficiency, the maximum tolerable amount (selenium 400ug/d) is used for intervention. For those with good nutritional status, the dietary recommendation amount is maintained.

Intervention type: DIETARY_SUPPLEMENT
Group type: EXPERIMENTAL
Intervention: Weak selenium
Description: The intervention was divided into two stages, the first stage lasted for 4 weeks, and the dosage used was the dietary nutrient recommendation amount, namely the dietary recommendation amount standard for early pregnancy (selenium 60ug/d), and the middle stage of pregnancy (selenium 65ug/d). The second stage lasts for 4 weeks. For subjects in selenium deficiency, the maximum tolerable amount (selenium 400ug/d) is used for intervention. For those with good nutritional status, the dietary recommendation amount is maintained.