Final answer:
The patient was admitted to the hospital due to fetal pleural effusion, which is the accumulation of fluid in the pleural cavity of the fetus.
Step-by-step explanation:
The reason for the patient's admission to the hospital was Fetal pleural effusion. Fetal pleural effusion refers to the accumulation of fluid in the pleural cavity of the fetus, which can cause respiratory distress. This condition may require medical intervention, such as fetal thoracentesis, which involves the removal of the excess fluid from the pleural cavity.