At a time when many traditional lenders are struggling, companies that join forces with doctors to make loans for in vitro fertilization, egg harvesting and other fertility treatments say their business is thriving. Fertility-finance companies are getting a boost from the banking industry's retrenchment. Mike Gilroy, Springstone's president, says business is robust because "if the time is right" to have a baby, "people want loans even in a sluggish economy." The loans have generated criticism from some doctors, concerned that they take advantage of couples' desire to have a baby at any cost. Some doctors won't offer the loans. Others worry that doctors who invest their own money in fertility-finance companies will push the loans on patients.