In the twin forums I've been involved with, there has always been discussion about the issues of 'term' - about half of all twins are born before 36 weeks. Many doctors think that twins should be delivered by 36 1/2 weeks, regardless of any other indication - it is just 'too hard' or 'too risky' to stay inside at that point. Research continues to not support that thinking - babies are really meant to stay in for 38 to 42 weeks, and while there are real and important reasons to take action sooner, the trend is toward increasing preterm births (many of them by c-section). Late preterm seems like it is safer - 34 - 36 weeks is 'close enough' ... but 'close enough' may not be as close as the doctors think.
Researchers seeing the trend (70% of preterm births are in the late pre-term period) have tried to determine what the impact of that gestational age of birth is - and it is definitely still a high-risk situation. Neurological impacts are particularly notable as major issues. Yes, their lungs are mature 'enough' and they usually have a suck reflex. But.
It is hard for the mom (dad, partner, family) to balance the risk profile effectively. And it is also hard for the OB to take a long-term look - the baby comes out 'looking healthy', and they are not the pediatrician or family doctor, so they do not have to deal with the long-term picture of developmental delays or neurological deficits. So it's important to make sure the care provider you have is aware of the issue, especially if you have a risk condition that might indicate pre-term birth as a potential offset to risks of a longer gestation (gestational diabetes being one issue that is tricky to balance - how big IS the baby, really? We don't have an accurate way to find out for sure, late term, so it becomes a guessing game).
In the twins research world, even 'near-term' (now effectively 37w - that last week between the end of late preterm and the start of term at 38 w - the terminology is changing, near-term used to have a different range, and was used interchangably, and is probably not settled even now) has been noted to have a laundry list of risks associated. 38 weeks really is the lower limit. It's really hard to reach that, though there's some indication that omega-3 fatty acids (especially DHA) can extend twin gestation (six days just by changing to DHA-enhanced eggs and eating a dozen a week).
Interestingly, the tie-in with DHA may be a contributing factor to both the preterm risk and the neurological factors. A diet low in Omega-3 fatty acids both increases your preterm labor risk and increases the risk of neurological issues for the baby. While this presentation is long and includes multiple factors, the discussion of DHA and other fatty acids is really important. (Someone ping me if you can't read it, I have a Medscape membership on the professional side, and I can't always tell if something is locked down to casual readership.)
It is reassuring that more doctors are being given access to the information about nutrition as an important factor. It is also reassuring that (as noted in that presentation) women are going to their doctors asking about nutrition, bringing it to the doctor instead of just waiting for the doctor to bring it to them. Keep doing that. They've noticed!