I work with a neonatologist who specializes in the perinatal follow-up of premature infants (at least until the age of three). He has accumulated years of data in our province. The very first question he asks when learning a baby's history is "Are the parents married?" Factoring out all other variables, this is the most consistent one in the cognitive and mental development (as measured via the Bayley's Developmental Assessment) of the prems in our area. Says something about the importance of a stable social environment in these situations. I would love to see his data used in longitudinal studies.
The biggest problem with any research on premature babies is that there are so many variables to consider. An 'uncomplicated' late-preterm infant could suffer long-term outcomes from a short, transient bout of hypoglycemia just after birth while an severely ill 26-weeker could escape seemingly unscathed.
