What Causes Gestational Diabetes With Low Lying Placenta In Women With Family History Of Neurofibromatosis?

Hi. IM 38 and pregnant on my fourth. Have gestinastional diabetes and have a low laying plancenta. Today got steroid injection for baby lung and again tomorrow as they not happy with baby aslo they mention the femur is short. What does this all mean. There is a history of neurofibromatosis in the family too. Please can u help. Thanking you.