The centre-back broke four bones in a hand during the pre-season trip to the Republic of Ireland, and has yet to feature in a campaign where results have disappointed.
He did make a return to the bench, but has yet to even feature for the reserves after missing recent games against York and Burnley's second string - attributed to a groin injury then calf problem.
Reid is needed to replace David Mirfin, who will miss the trip to the County Ground due to a one-match suspension after being sent off for two yellow cards against Brentford last weekend.
If Reid is not able to slot in alongside Niall Canavan in the centre of defence then it is likely Tom Newey will move inside from the left-back role, with Callum Kennedy stepping off the bench to replace him at full-back.
Karl Hawley (ankle) remains a doubt, while Michael Collins (tendonitis) and Damien Mozika (ankle) are still lacking fitness so unlikely to feature.
The Iron could have a total of four former Swindon players in their side against the Robins. Leon Clarke, the striker on-loan at the Iron from Charlton, is the most notable having left the club following a very public disagreement with manager Paolo Di Canio.
Kennedy moved to Glanford Park after being released by Swindon this summer, while David Prutton and Mike Grella also had spells with the Robins.
Di Canio should have captain Alan McCormack back, after missing the last two games with a hamstring problem. He is likely to play alongside the experienced Tommy Miller in central defence, with Alan Navarro ruled out for up to four weeks with medial ligament damage.
John Bostock, on loan from Tottenham, is also expected to retain his place in Di Canio’s starting XI having impressed on his debut against Coventry last weekend.