Glucose testing advice?

I failed my 1 hour test, but the cutoff number was 130 and I only got 131 so the doctor told me it was my choice to do the three hour one or not. Well the three hour seems like hell and I don't have the time so I opted out but my mom is telling me I'm killing my baby now. What are the dangers of going undiagnosed if I really have it? I only failed by one number so my doctor didn't seem that concerned.