A 32-year-old woman, gravida 2 para 1, at 30 weeks gestation comes to the office for a routine prenatal visit. The patient's pregnancy has been uncomplicated, and she has had no vaginal bleeding or contractions. She has continued to jog daily throughout the pregnancy but is becoming more fatigued by the end of her workouts. The patient has no chronic medical conditions, and her only medication is a daily prenatal vitamin. She does not use tobacco, alcohol, or illicit drugs. Blood pressure is 110/70 mm Hg, pulse is 76/min, and respirations are 20/min. Fetal heart tones are normal. Physical examination is unremarkable. Compared to a nonpregnant state, this patient most likely has which of the following hematologic changes?

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11ec160b_3cd7_31c2_9249_a3a1cea74392_MD0001_00 During normal pregnancy, the maternal hematologic system undergoes several adaptations to accomodate the developing fetus and placenta. These adaptations include: Increased plasma volume, which begins at approximately 6 weeks gestation and increases rapidly until term, resulting in a total plasma volume increase of 30%-50% when compared to a nonpregnant state. Increased plasma volume helps reduce positional hypotension caused by uterine compression of the vena cava (ie, decreased venous return when patient is supine or standing) and ensures adequate circulating volume for fetal nutrient delivery and waste removal. Increased maternal red blood cell mass. Pregnant women generate higher levels of erythropoietin, which drives the production of new red blood cells and increases red blood cell mass by 20%-30%. This increase helps ensure adequate oxygen delivery to the fetus and placenta; it also protects against excessive blood loss associated with delivery (eg, postpartum hemorrhage). Because the expansion of maternal blood plasma volume is greater than the increase in maternal red blood cell mass, pregnant women typically have a mild reduction in hemoglobin concentration due to dilution. Educational objective: Pregnant patients have marked increases in blood plasma volume (by 30%-50%) and red blood cell mass (by 20%-30%), which helps improve fetal nutrient delivery while also protecting against excessive blood loss during delivery. Because the expansion of blood plasma volume is greater than the increase in red blood cell mass, pregnant women typically have mildly decreased hemoglobin concentrations (ie, dilutional anemia). __________ References: Hematologic complications of pregnancy. (http://www.ncbi.nlm.nih.gov/pubmed/23953339)

A 32-Year-Old Woman, Gravida 2 Para 1, at 30 Weeks