Question on foaling....?

OK, I'm not a breeder, so about the only thing I know about is what we experienced when Ruby had her two foals, and what I've read/heard, so I'll apologize if I say something stupid.

Question: is it true that a pregnant mare will hold off on having her foal if she's continually disturbed by people/other horses?

Details: One of my friends has a mare who is pregnant. She's apparently shown all the signs of being ready to give birth (nearly a week ago), but has not. The mare is being kept in a stall with other horses in neighboring stalls, and my friend checks on her every three-four hours (all through the day and night). She tells me that the mare's udder is sore, and so she won't let the foal suckle, and that's why she has to check on her. There is also a baby monitor in the barn.
It's probably none of my business, and I could be way off base with my assumptions, but at the very least I may learn something.

Mares can hold off on foaling. Part of the survivial instinct.

We have a mare that four years ago was having all the signs of foaling but refused to lay down and have the dang thing. After a few days, we made a new area for her. Two hours later she had the foal.

Last year she started on the 1st but it was too busy at the barn and held off until early on the 3rd.

Yesterday my husband called me and said I think mare is looking for her straw. We'll make the foaling pen tonight. (she's "due" 4/13)

Horses definitely can hold off foaling if something disturbs or frightens them. One mare was in a field during a lightening storm and refused to foal till she was taken out. Then of course some mares just seem to delight in teasing us! But yes, if a mare is not comfortable with a situation she will hold off foaling as long as possible. Most mares are uncomfortable with people watching so they will wait until they leave and then foal.

I have approximately 40-50 miniature horse foals born every year and to be comletely honest with you it should not affect a mare's gestation time. We had one mare in 2008 who was showing signs of having a foal for approximately 3 weeks and when she finally did have him he was completely fine. When a mare feels safe and content she will have the baby and until then all you can do is watch her.