A pregnant woman's diet may not meet her need for folates. A good source of this nutrient is:

Choice A reason: A miscarriage is defined as a spontaneous abortion of a fetus before the 20th week of gestation. It is a natural pregnancy loss that occurs before labor begins and is usually caused by chromosomal abnormalities, infections, or maternal health problems.

Choice B reason: A miscarriage is not often attributed to careless maternal behavior such as poor nutrition or excessive exercise. These factors may affect the quality of life of the mother and the fetus, but they are not the main causes of miscarriage. Most miscarriages are not preventable and are not the fault of the mother.

Choice C reason: A miscarriage that occurs before the 12th week of pregnancy may manifest only as moderate discomfort and blood loss, but this is not always the case. Some women may experience severe cramping, bleeding, and tissue passing from the vagina. Others may have no symptoms at all and only discover the miscarriage during a routine ultrasound.

Choice D reason: A miscarriage occurs in more than 5% of all clinically recognized pregnancies. The actual rate of miscarriage is estimated to be 10% to 20%, but many women may not realize they are pregnant or may not report the loss to their health care provider.

Choice A reason: Vascular volume increases during pregnancy to meet the increased oxygen and nutrient demands of the fetus, not to compensate for decreased renal plasma flow. In fact, renal plasma flow increases by 50% to 80% during pregnancy to facilitate the excretion of metabolic wastes.

Choice B reason: Vascular volume increases during pregnancy to ensure adequate blood supply to the uterus and other organs, not to prevent maternal and fetal dehydration. Dehydration can occur due to vomiting, diarrhea, or inadequate fluid intake, and it can be prevented by drinking enough fluids and replacing electrolytes.

Choice C reason: Vascular volume increases during pregnancy to provide adequate perfusion of the placenta, which is the main organ of gas exchange and nutrient delivery for the fetus. The placenta receives about 10% of the maternal cardiac output at term.

Choice D reason: Vascular volume increases during pregnancy to support the growth and development of the fetus and the maternal tissues, not to eliminate metabolic wastes of the mother. Metabolic wastes are eliminated by the kidneys, lungs, skin, and gastrointestinal tract.