I am 27, diagnosed with early onset Parkinson's disease and looking to start a family. Is there any known issues in respect to Parkinson's and pregnancy?

Adverse effects. There is probably no problems with the pregnancy itself but there are some research findings that the pregnancy itself may adversely affect and aggrave the pd, specifically worsening the motor(muscular) deterioration. See: http://www.Ncbi.Nlm.Nih.Gov/pubmed/10634252.
Some. First let me express my sympathy, to be so young and to deal with these issues is a real challenge. I would recommend the parkinson disease foundation website. No direct correlation between pd and pregnancy, either ability to concieve to carry or delivery. Concern is for medications which are mostly cat c. Animal risks have shown concern. Finally the challenge of parenting are to be consid.