When Mary Donovan found out she was pregnant, she never considered going anywhere but Jackson Memorial Hospital to have her baby. Sure, the accommodations at the sprawling campus near downtown Miami don't offer the ambience of the hotel-like rooms at some hospitals. But she thought Jackson offered something better: specialists and one of the best neonatology units in the country. At 41, Donovan was among the growing number of women falling into the category of high-risk pregnancy. And that has driven up the need for hospitals like Jackson.