The Joy in Birth blog posted a summary of a very interesting study of whether the administration of pitocin during labor affects a child's later behavior.
As her Ph.D. thesis, Claire Winstone devised a survey to see whether the personalities or behaviors of three-year-olds differed based on whether their moms had pitocin or not. She found two distinguishing characteristics:
The first was called "Assertiveness" , which describes a socially appropriate way that babies and children communicate their need for help and comfort when they are feeling uncomfortable or unsafe. ... babies born with Pitocin, whose mothers reported having had a more challenging time during labor and delivery, appear to have a higher need to be assertive because they seem to experience more discomfort, but are apparently less effective in asserting their needs and getting them met when they feel unsafe or uncomfortable.
The second factor was called "Need to Control Environment" and this summarizes what seems to be a higher level of discomfort or insecurity, particularly in response to "outside-in" influences (e.g., reacting to food with digestive problems or being picky eaters; problems coping with other people's timing and structure, refusing help from others) and increased or exaggerated efforts to control their environment.
Blog author FairyMom doesn't provide a link to the study or information on who Winstone is; I think she may be this prenatal psychologist. In any case, the synopsis of her study is worth reading on the blog.