Nongenetic Maternal Factors

There is a high correlation between birth weights of siblings that extends to cousins. The nongenetic, maternal nature of this effect is demonstrated by embryo transfer and cross-breeding experiments. For example, a small-breed embryo transplanted into a large-breed uterus will grow larger than a small-breed embryo remaining in a small-breed uterus. Furthermore, partial reduction in fetal number in a polytocous species such as the rat produces greater than normal birth weights in the remaining offspring. Conversely, embryo-transfer of a large-breed into a small-breed uterus will result in a newborn that is smaller than in its natural large-breed environment. Such evidence demonstrates that fetal growth is normally constrained, and that this constraint comes from the maternal environment. This is a physiological process and includes the maternal-specific capacity of uterine size, placental implantation surface area of the uterus, and uterine circulation, which together support the growth of the placenta and its function.

New Mothers Guide to Breast Feeding

New Mothers Guide to Breast Feeding

For many years, scientists have been playing out the ingredients that make breast milk the perfect food for babies. They've discovered to day over 200 close compounds to fight infection, help the immune system mature, aid in digestion, and support brain growth - nature made properties that science simply cannot copy. The important long term benefits of breast feeding include reduced risk of asthma, allergies, obesity, and some forms of childhood cancer. The more that scientists continue to learn, the better breast milk looks.

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