I'm not sure how much help I can be because I haven't specifically researched the connection between these issues and maternal age. Still, if your friend is in good health and has birthed big babies vaginally before who were in good condition at birth, other than the genetic concerns, I'm not sure what the fuss is about other than the usual one, that is, to make variation from average "abnormal." It seems to me that your friend needs only to take care of herself in the ways any pregnant woman should regardless of age. She needs to eat right, take iron if she is anemic, and get regular, moderate exercise. It is likely she will be having another large baby, so it would be prudent to avoid epidural analgesia so that she can be mobile and can push effectively. She might also think about giving birth on hands and knees, which is the most favorable position for avoiding and alleviating shoulder dystocia (the head is born, and the shoulders hang up behind the pubic bone), or at least she should be prepared to turn to hands and knees should shoulder dystocia occur. If she is a large woman or has birthed several children, she may have a pendulous abdomen. Some midwives recommend a belly band (a towel or sheet can be used) to bring the belly back up and in so that the uterus lines up with the vagina. This can make contractions more effective. The other thing, of course, is to find a care provider who practices physiologic care and treats according to the specific situation in individual women, not by category.
-- Henci