In a large multi-site study, Shapiro-Mendoza et al.
(2008) found that 22.2% of the 26,170 late-preterm births
had experienced at least one complication that could lead
to a prolonged hospital stay, compared to 3% of the
377,638 term infants; the 34-week gestation age group had
the highest morbidity (51%), and the percentage gradually
decreased with each advancing week, down to 5.9% morbidity
at 37 weeks gestation.