A 29-year-old woman, gravida 1 para 0, at 16 weeks gestation comes to the office for prenatal care. The patient was hospitalized at 7 weeks gestation for hyperemesis gravidarum. Since the hospitalization, she has received intravenous hydration several times in the emergency department due to dehydration from persistent nausea and vomiting. She is able to tolerate prenatal vitamins, which she takes with metoclopramide. However, despite taking antiemetics frequently, the patient is unable to eat or drink much. Blood pressure is 90/50 mm Hg. Prepregnancy BMI was 18 kg/m². Weight is 50 kg (110.2 lb), a decrease of 2 kg (4.4 lb) from prepregnancy weight. Fetal heart tones are normal by Doppler. The patient is concerned about her weight loss and whether it will affect the baby. The fetus is at greatest risk for which of the following complications?

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11ec25c8_da3e_84f4_bc81_59cfc86c3531_MD0003_00 Recommendations for weight gain in pregnancy depend on prepregnancy BMI. Inadequate or excessive weight gain is associated with an increased risk for fetal and maternal complications. Underweight (BMI <18.5 kg/m²) patients are advised to gain 12.7-18.1 kg (28-40 lb) during pregnancy. ² This patient's prepregnancy BMI was 18 kg/m², and she presents with hyperemesis gravidarum and weight loss. Hyperemesis frequently resolves by 16-20 weeks gestation but can persist until delivery. Although the pathophysiology of hyperemesis itself does not affect the fetus, poor intake and inadequate weight gain increase the risk of fetal growth restriction and low birth weight. Poor maternal weight gain is also a risk factor for preterm delivery but not for postterm birth (Choice F). ² (Choice A) Risk factors for fetal anemia include fetomaternal hemorrhage, maternal alloimmunization, and in utero infection (eg, parvovirus), but not poor weight gain in pregnancy. In contrast, fetal growth restriction is a risk factor for neonatal polycythemia/hyperviscosity. (Choice B) A cystic hygroma is a congenital malformation caused by lymphatic system obstruction in the fetal neck. It is associated with fetal aneuploidy (eg, Turner syndrome) but not with inadequate weight gain in pregnancy. (Choice D) The chief risk factor for neural tube defects is inadequate folate consumption. This patient is able to take her prenatal vitamins, which contain folate, making a neural tube defect an unlikely complication. (Choice E) Fetal organomegaly is a potential complication of maternal gestational diabetes mellitus and a result of fetal hyperinsulinemia. Excessive weight gain during pregnancy is a risk factor for gestational diabetes mellitus and its complications. Educational objective: Pregnant patients who are underweight or do not gain an appropriate amount of weight during pregnancy are at increased risk for fetal growth restriction and preterm delivery. References: Recommendations for weight gain during pregnancy in the context of the obesity epidemic. (http://www.ncbi.nlm.nih.gov/pubmed/20966705)

A 29-Year-Old Woman, Gravida 1 Para 0, at 16 Weeks