Soru

A $32$-year-old woman, gravida $3$, para $2$, at $34$ weeks gestation comes to the clinic for a routine evaluation. She reports feeling more fatigued over the past two weeks, along with mild shortness of breath when climbing the stairs at her home. She occasionally notices her heart beating faster than usual. She reports good fetal movement and denies chest pain, cough, or orthopnea. Her past medical history is unremarkable. Blood pressure is $110/64$ mm Hg, pulse is $104$/min, and respirations are $18$/min. Pulse oximetry shows $98\%$ on room air. Physical examination reveals clear lungs bilaterally. Cardiac auscultation shows a grade $2/6$ systolic ejection murmur best heard at the left sternal border without radiation. Trace bilateral pitting edema is present at the ankles.

Laboratory and diagnostic studies show the following:
Hemoglobin: $11.2$ g/dL
Hematocrit: $33\%$
Platelet count: $185,000/\text{mm}^3$
Serum creatinine: $0.5$ mg/dL

Arterial blood gas (room air):
pH: $7.45$
$\text{PaCO}_2$: $29$ mm Hg
$\text{PaO}_2$: $102$ mm Hg
$\text{HCO}_3^-$: $20$ mEq/L

An electrocardiogram demonstrates normal sinus rhythm with left axis deviation.

Which of the following is the most appropriate next step in the management of this patient?