What are the side effects of low potassium to unborn child?

Heart is in danger . Most of the k+ in the body is inside the cells. While in the uterus, placenta works to support fetal vital organs (gas exchange, toxins excretion, etc.) after birth newborn needs to support himself and with severe hypokalemia most of the vital organs would be in failure: heart (rhabdomyolysis & arrhythmia), kidneys, gastrointestinal (paralitic ileus), respiratory - from ascending paralysis, etc.