This week I picked up a recent issue of Psychology Today and read an article titled "Mother, Damned-est," about the legacy of poor mothering in people's lives. The issue of motherhood is a very relevant one for BPD. Lots of people with BPD had bad experiences with a caregiver figure (notice that I didn't say mother-- because all caregivers are important to development), and many have trouble being stable parental figures for their kids. One of the most common concerns brought up by family members in the BPD forum is about the effect their BPD loved one is having on children in the family.
Having BPD does not mean that you can't be a good parent. But it takes a lot of work, and sometimes people with BPD need both treatment and parent education to optimize their parenting skills.