Fetal growth can be affected by the protein levels in a mother-to-be's diet, but a pregnant woman might be uncertain about the exact amount and type of protein she needs. Not only does protein intake affect a fetus' growth, it also affects the development of important organs, including the brain. Fortunately, sources of protein are easy to find, and most pregnant women should have no trouble maintaining an adequate intake to support fetal growth and development.
A developing fetus needs protein to build all of the cells of its body. The maternal diet supplies all of the protein a baby needs, so if a pregnant woman is deficient, her baby can suffer. Because the baby grows more rapidly during the second and third trimesters, protein levels during the latter half of the pregnancy are more important than earlier in fetal development. During the final trimester, maternal protein intake supports the growth of the fetal brain, so not getting enough protein during this time period can affect mental functioning of the child.
Protein deficiencies in the mother can lead to hampered growth in the fetus; in severe cases this can take the form of intreauterine growth restriction, or IUGR. Babies with IUGR fall below the length and weight for their particular phase of fetal development. This condition can lead to stillbirth or problems after birth, including respiratory, neurological, circulatory and intestinal disorders.
Pregnant women need about 70 grams of protein every day, compared to about 45 grams daily for women who are not pregnant. This amount can be averaged out over the course of about a week, so if you don't get much protein one day, you can eat more over the next few days to make it up without harming your baby. Some special pregnancy diets, such as the Brewer Pregnancy Diet, advocate protein intake of 80 to 100 grams per day. You should talk with your doctor or midwife to determine the appropriate level of protein intake for you and your baby.
The best protein sources during pregnancy are low in saturated fat and high in other beneficial nutrients that support fetal growth. Fish and seafood are particularly good sources, since they also contain omega-3 fats that promote brain development. Lean meat, eggs, poultry and dairy products are also good protein sources for a pregnant woman. Animal sources are complete proteins, containing all of the necessary amino acids in a single food. Vegetarian protein sources, such as beans, tofu and nuts, might need to be paired with other sources in order to get a full complement of amino acids. For example, beans and rice each contain different amino acids, but together provide all of them.