Scunthorpe were defeated 1-0 away at title-chasing Bournemouth on Easter Monday.
Brett Pitman's goal early in the first half was enough to see off United, who fell back into the relegation zone as a consequence of Oldham's 1-1 home draw with Colchester, which saw the Latics climb back above them.
The Iron entered the game making two changes from the side that defeated Leyton Orient.
David Mirfin returned to the starting line-up to come in for Paul Reid, who was suffering from a back injury sustained three days ago.
Anthony Forde meanwhile replaced Akpo Sodje as Scunthorpe switched to a 4-5-1 formation.
Eirik Holmen Johansen started in goal, with Eddie Nolan, David Mirfin, Niall Canavan and Tom Newey forming the defence.
The midfield consisted of Mark Duffy, Michael Collins, Jimmy Ryan
, Forde and Andy Barcham, while Karl Hawley led the attack.
The substitutes were Sodje, James Severn, Christian Ribeiro, Mike Grella, Robbie Gibbons, Luke Hornsey and James Alabi.
After some good early pressure, it was Ryan who had the first chance of the game three minutes in but he dribbled towards goal before poking well wide with his right foot.
Nevertheless, after what was a fairly even opening, it was the hosts who took the lead in the 12th minute.
The goal came as the ball fell invitingly for Pitman, who struck home from close range after his striker partner Matt Tubbs had headed a left wing cross from Marc Pugh back across goal.
In a half of few chances, the Cherries tried to press for a second but Scunthorpe also had decent spells of possesion, with Duffy forcing Ryan Allsop to stoop down to save from a low drive.
As the game edged towards half-time, United continued to enjoy a lot of time on the ball in the Cherries' half, and an opening almost fell for Hawley after a stumble from a home defender but Allsop was quick to stub out the threat.
The last chance before the break came Pugh's way for the hosts as he drove forward and sent in a cross-cum-shot which nobody could get on the end of and drifted wide.
In the 51st minute, Johansen was drawn into a great stop, diving down low to his left to tip away a stinging Charlie Daniels effort which was heading for the bottom corner.
Just three minutes later, Duffy had his side's best chance of the game so far as he drove forward, cut inside from the left and drilled a low effort towards the right hand post but just wide. On 55 minutes he cut inside to fire another effort towards goal, which Allsop stopped.
The hosts came close to doubling their lead on 57 minutes, as Eunan O'Kane played in Tubbs, who played the ball back for Pitman, whose effort from 15 yards clipped the top of the crossbar and went over.
Six minutes later, Johansen was once again called into action as he tipped Matt Ritchie's close-range effort around the post after Pugh's left-wing cross had found him.
In the 66th minute, Johansen had to make another stop, this time from O'Kane, who found space on the edge of the area and fired an effort goalwards which the Norwegian pushed away.
A double Scunthorpe change was made on 72 minutes as Alabi and Sodje replaced Forde and Hawley.
Taking advantage of a Cherries defender slipping up in the wind, Alabi nearly forced an opening eight minutes later but his effort was deflected into the arms of Allsop.
With the home attack not enjoying so much productivity as the half wore on, Scunthorpe came close again as Nolan fired over the crossbar after a scramble following Duffy's corner.
Grella then replaced Barcham as Scunthorpe seeked some fresh impetus going forward in the last few minutes.
There were three minutes of stoppage time played but the visitors couldn't find the breakthrough.
Allsop, Francis, Cook, Elphick, Daniels, Ritchie (Fogden, 90), Arter, O'Kane, Pugh (MacDonald, 81), Tubbs (McQuoid, 74), Pitman.
Substitutes not used:
Jalal, Fletcher, Seaborne, Hughes.
Johansen, Nolan, Mirfin, Canavan, Newey, Duffy, Collins, Ryan, Barcham (Grella, 88), Forde (Sodje, 72), Hawley (Alabi, 72).
Substitutes not used:
Severn, Ribeiro, Gibbons, Hornsey.
7,465 (146 away).