What could I do to prevent gestational diabetes? My mother developed it, is it something I would be predisposed too.

You are not necessarily predisposed to it.  Gestational diabetes results in large part from the rise in placental hormones during pregnancy, but increased insulin requirements also play a role.  Supporting the liver's role of detoxifying excess hormones during the pregnancy can help prevent excess placental hormones from causing a problem.  This can be done primarily by increasing your intake of vitamin B rich foods to help improve methylation.  Chromium supplementation has also been shown to help since it helps increase insulin sensitivity.  Chromium polynicotinate is the best form.  I recommend 200mcg three times daily with meals.  Magnesium malate or citrate will also help increase insulin sensitivity and reduce the risk of preeclampsia.  I recommend 400mg three times daily with meals.