题目内容
One of medicine's fundamental beliefs about pregnancy and the development of the human fetus has been challenged. Until recently, it was thought that the fetus was a parasite capable of extracting all the nutrients it needed from the mother. It is now realized that adequate nutrition during the entire course of the pregnancy is necessary for proper fetal development.
In early pregnancy, certain changes occur in the mother's gastrointestinal tract, resulting in more efficient absorption of specific nutrients, such as iron and calcium. Furthermore, the maternal blood supply increases, so that nutrients can be transported via the uterine and placental blood systems: If the mother is undernourished, this "lifeline" to the fetus will be inadequately developed. Finally, fat is accumulated within the body to store the energy necessary for lactation (milk production), This preparation for lactation is so important that if the mother is inadequately nourished, it will take place even at the expense of fetal growth. It is a logical developmental occurrence, since in the natural world, no infant can survive without successful breastfeeding, and thus fetal growth is less of a priority.
According to the passage, which of the following is required for lactation？
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【C1】
【C11】
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