Gestational diabetes is usually a temporary type of hyperglycemia seen in some pregnant women, usually late in their pregnancy.  The cause is unknown, but it is thought that some hormones from the placenta increase insulin resistance in the mother, causing elevated blood glucose levels.  Women are screened for gestational diabetes between their 24th and 28th week of pregnancy.  If gestational diabetes is found and not addressed, the baby is likely to be larger than normal, be born with low glucose levels, and be born prematurely.  Gestational diabetes also raises the risk of eventually developing type 2 diabetes, for both the mother and the baby.