Conor Chaplin’s ninth goal of the season gave the Blues the lead but Frankie Kent levelled for Peterborough leaving the scoreline 1-1 at half-time.
Sone Aluko returned to the Blues squad and the starting line-up after three months out with a knee injury, while Kayden Jackson was also back in the XI.
Aluko, making only his second league start of the season having been out since the 6-0 Papa Johns Trophy victory over Northampton at the end of August, was one of the number 10s alongside Chaplin with Kyle Edwards dropping to the bench.
Jackson, who almost joined Peterborough in the summer of 2018 but opted instead to sign for Town, replaced Freddie Ladapo, who was also among the subs, as the lone central striker in a team otherwise unchanged from the 1-1 home draw with Fleetwood just over a week ago.
Peterborough, who switched to a back three, made three changes from the side which lost 2-1 at home to Barnsley last week with former Blues striker Jack Marriott, Kelland Watts and Hector Kyprianou coming into the team, while Jeando Fuchs, Ben Thompson and Ephron Mason-Clark dropped to the bench.
In freezing conditions with patches of frost on the pitch close to the Cobbold Stand, the visitors saw most of the ball in a cagey early period with no penalty area action at either end.
In the 10th minute Janoi Donacien pulled up with what looked a significant injury, perhaps a hamstring pull, but after treatment the defender continued. However, four minutes later, with Town still to get going, Donacien sat down after the ball had gone out of play and Kane Vincent-Young took over.
The game continued in the rather pedestrian manner in which it had started but the Blues began to get on top and in the 20th Aluko struck the first shot, but his effort hit into the ground from just outside the area on the right bounced harmlessly wide.
However, a minute later, Town went in front. Vincent-Young laid the ball back to Sam Morsy on the edge of the box on the right, the skipper looped a cross into the area and Chaplin got in front of Kent and flicked a head across Posh keeper Lucas Bergstrom and into the corner of the net.
The diminutive forward slapped his forehead in delight having scored a rare header, his ninth goal of the season.
Posh went close to a leveller in the 27th minute from a 30-yard free-kick. Jonson Clarke-Harris, League One’s 14-goal top scorer, smashed a superb strike towards Christian Walton’s top left corner and with the keeper perhaps hampered by the sun, the ball clipped the top of the bar and flew into the Sir Bobby Robson Stand as the Town number one collided with the post.
Town weren’t far away from doubling their lead on the half hour from a free-kick on the right. Keeper Bergstrom failed to deal with the high ball to the back post and Morsy lobbed it back into the area, but it was cleared. Cameron Humphreys sent a return ball from the left towards Wes Burns but the Welshman was offside.
And in the 31st minute, the visitors equalised. From a short corner on the right, Kwame Poku crossed towards the far post and Kent nodded into the net unchallenged with Walton, perhaps surprisingly not wearing a cap, again appearing to be struggling with the sun as the ball came over.
On 38, with the Blues still to really impose themselves on the visitors, Aluko did superbly to trick his way to the byline on the right and cut the ball back. However, Bergstrom was able to pounce on it, the keeper taking an accidental kick from Chaplin as he gathered.
As the half moved into its final five minutes, the Blues began to put Posh under a prolonged spell of pressure for the first time.
In the 42nd minute, a Burns cross from the right was cleared to Morsy on the right of the box and the Egyptian international hit a powerful shot but straight down the throat of Bergstrom.
A minute later, Aluko shot wide after Davis had knocked a cross from the right down to him on the edge of the area.
In injury time, just before the whistle, Davis turned the ball into the area from the left and Jackson appeared to be fouled, however, the linesman’s flag had already been raised.
The end of the half was greeted by a very muted response following a thoroughly lacklustre first 45 minutes.
The opening spell had been rather stop-start with the injury to Donacien and Peterborough taking their time over every restart but Town had started to show some threat when Chaplin netted his excellent headed goal.
That ought to have been the spur for the Blues to really impose themselves, but as so often in recent weeks they allowed the opposition back into the game via a ball into the box.
But on the balance of the half, the visitors deserved to go in level with Town’s performance lacking tempo or any urgency.
Town: Walton, Donacien (Vincent-Young 15), Woolfenden, Burgess, Burns, Morsy (c), Humphreys, Davis, Chaplin, Aluko, Jackson. Subs: Hladky, Keogh, Leigh, K Edwards, Ahadme, Ladapo.
Peterborough: Bergstrom, Watts, Butler, R Edwards, Kent, Taylor, Clarke-Harris (c), Poku, Marriott, Kyprianou, Ward. Subs: Blackmore, Knight, Fuchs, Mason-Clark, Burrows, Jones, Thompson. Referee: Ollie Yates (Staffordshire).