A 39-year-old woman, gravida 1 para 0, at 34 weeks gestation comes to the office for a routine prenatal visit. She has good fetal movement and some lower abdominal pressure. Other than a cough and nasal congestion during the first trimester, the patient has had an uneventful pregnancy. Her first trimester screening and fetal anatomy ultrasound were both normal. She was diagnosed with hypertension 5 years ago for which she takes labetalol. The patient drinks 2 cups of coffee daily but does not use tobacco, alcohol, or illicit drugs. She is a nurse in the neonatal intensive care unit and plans to work until her due date. Blood pressure is 142/82 mm Hg and fundal height is 30 cm. Ultrasound reveals a biparietal diameter consistent with 32 weeks and abdominal circumference consistent with 27 weeks gestation. A normal amount of amniotic fluid and a posterior placenta are present. Estimated fetal weight is at the 8th percentile for gestational age. Which of the following is the most likely cause of this fetus' condition?

Question

A 39-year-old woman, gravida 1 para 0, at 34 weeks gestation comes to the office for a routine prenatal visit.  She has good fetal movement and some lower abdominal pressure.  Other than a cough and nasal congestion during the first trimester, the patient has had an uneventful pregnancy.  Her first trimester screening and fetal anatomy ultrasound were both normal.  She was diagnosed with hypertension 5 years ago for which she takes labetalol.  The patient drinks 2 cups of coffee daily but does not use tobacco, alcohol, or illicit drugs.  She is a nurse in the neonatal intensive care unit and plans to work until her due date.  Blood pressure is 142/82 mm Hg and fundal height is 30 cm.  Ultrasound reveals a biparietal diameter consistent with 32 weeks and abdominal circumference consistent with 27 weeks gestation.  A normal amount of amniotic fluid and a posterior placenta are present.  Estimated fetal weight is at the 8th percentile for gestational age.  Which of the following is the most likely cause of this fetus' condition?

Quizplus · Accepted Answer

11ec25c8_da2c_0f3d_bc81_af3cec8918b9_MD0003_00 Fetal growth restriction (FGR) is defined as an estimated fetal weight <10th percentile for gestational age. Fetuses with growth restriction have increased risk of intrauterine demise and neonatal morbidity/mortality (eg, preterm delivery). FGR can be characterized as symmetric or asymmetric. Congenital disorders or insults during the first trimester (eg, aneuploidy, infections) are the most common causes of symmetric FGR (eg, the entire fetus is affected). Asymmetric FGR, the result of placental dysfunction during the second and/or third trimester, is associated with conditions that cause placental insufficiency (eg, hypertension, pregestational diabetes). In normal fetal development, the fetal abdomen grows exponentially during the second and third trimester. Insults (eg, hypoxemia) at this stage of pregnancy cause fetal blood flow to be redistributed to the vital organs (eg, brain) and away from the abdomen, resulting in an asymmetric, or "head-sparing," growth pattern. In this patient, the fetal head is 2 weeks smaller and the abdomen is 7 weeks smaller than expected for gestational age, indicating asymmetric FGR. The patient's hypertension is the most likely cause. Even when well controlled, hypertension can cause underdevelopment of the spiral arteries in the placenta, resulting in increased vascular resistance. These vascular alterations can cause placental insufficiency and, subsequently, asymmetric FGR. (Choice A) Advanced maternal age (>35) is associated with an increased risk for fetal chromosomal abnormalities and maternal comorbidities (eg, diabetes, hypertension); it is not an independent risk factor for FGR. > (Choice B) Cocaine, tobacco, and alcohol use is associated with FGR, but caffeine use is not. (Choice C) First trimester congenital infection (eg, malaria, toxoplasmosis, syphilis, cytomegalovirus, rubella, varicella) results in symmetric FGR. (Choice E) This patient had a negative first trimester aneuploidy screening and a normal anatomy ultrasound, making trisomy 21 unlikely. Educational objective: Asymmetric fetal growth restriction (FGR) is due to second and third trimester placental insufficiency (eg, hypertension) that results in a restriction of abdominal growth that is more pronounced than the restriction in head growth. Symmetric FGR is due to congenital disorders or first trimester infections. References: ACOG Practice bulletin no. 134: fetal growth restriction. (http://www.ncbi.nlm.nih.gov/pubmed/23635765)

A 39-Year-Old Woman, Gravida 1 Para 0, at 34 Weeks