Severe Hyponatremia Associated with Use of Black Cohosh during Prolonged Labor and Unsuccessful Home Birth

Introduction There has been an increase in the use of herbal supplements during pregnancy, which are frequently of unproven efficacy and safety. We present a case of severe hyponatremia and altered mental status associated with the use of black cohosh during prolonged labor. Case A 39-year-old primigravida at 385/7 weeks of gestational age presented to the emergency department after she became disoriented and lethargic while laboring at home with a midwife. She had consumed several doses of black cohosh to induce and augment labor. On presentation, she was nonverbal and unable to follow commands. Her serum sodium was 114 mmol/L (range, 132-145 mmol/L), serum osmolality was 253 mOsm/kg (range, 275-300 mOsm/kg), urine osmolality was 190 mOsm/kg (range, 300-900 mOsm/kg), and urine sodium was < 10 mmol/L. The patient soon became uncooperative and combative and a cesarean section was performed. Postoperatively, she was transferred to the intensive care unit for monitoring and correction of her sodium. Her mental status returned to baseline and she was subsequently discharged home without further complication. Discussion Clinically significant hyponatremia associated with pregnancy is rare. Further investigation is needed to evaluate the safety and efficacy of black cohosh and other commonly used herbal supplements during pregnancy and labor.