No one had held my daughter yet and she was 37 weeks...and she still got NEC and needed drastic surgery to survive at 48 hours old. PLEASE don't torture yourself. They don't know what causes it, but w/premies as little as yours, the thought is that the gut is tissue-thin and so bacteria can get in and out, it's not much of a barrier in these guys. It's a heartbreaking disease because it's very hard to prevent if it is going to happen. And no, rocking isn't harmful, or they wouldn't have the chairs there. Babies in utero are used to movement, it's their norm. When they're in the isolette, they don't get to move much at all. The rhythm of rocking actually helps normalize vital signs sometimes.
I like the idea of checking with the local NICU about their policies prior to considering this again. Our NICU wouldn't let me hold my daughter until a couple of days post-op, which means she had to have been 4-5 days old at that point. I think I'd held her once before but I was so stoned on the mag sulfate that I have almost no memory of even being able to see her with the cerebral edema and no glasses. In the NICUs where I've worked, they've allowed kangaroo holding with most babies 1000 gms and above. Even with the smaller guys, they encourage holding hands, and they give you a "lovey" that you put into your bra, then they put it up against the baby in the isolette so they carry your smell and warmth to the baby. If a baby's vital signs aren't stable (they have trouble keeping his oxygen levels up, for example), then they won't let you hold him. But a baby who can maintain their heart rate and saturation levels should be able to be held. They monitor the vital signs; it's pretty easy for the trained eye to see when a baby is being stressed.
I have known NICU nurses who are, to put it mildly, controlling (I vividly remember an argument with an RN about swaddling). It is more work for them to work with you in kangaroo care and other comforting measures. Hopefully, none of you will ever have a NICU baby again! But finding out the policies, and knowing what the literature says (in some small towns, you may be more current than the nursing staff, sadly), will help you advocate for a baby's needs...if you ever have to go through this again. I hope no one here ever does!
Before my daughter was born, I had worked with NEC babies. It's a disease that breaks my heart, all the more so that my daughter will always pay the price. Unfortunately, it cost her entire large intestine, three surgeries (and probably more) and the caution that pregnancy would be extremely hazardous for her. I know, I have her, and I'm grateful every day. But it was close, and I can only imagine your pain and your fears.
Mom to Rebecca, now 16 and honor student. 37-week, two months in NICU for her thanks to NEC and meningitis. One month in hospital for me, HELLP syndrome and severe hyper-reflexia. All healthy now, more or less!