Our lovely 12 week old baby has always been fairly good at night. Goes down about 8 o'clock, dream feed at 11 then used to wake anytime between half 3 to 5 often accepting a dummy for an hour or two rather than a bottle. Then back to sleep until half 7/8 o'clock. However, this week he had his 12 week jabs and since then things have changed drastically. These last few nights he's woken every 2 or 2 and half hours. He won't be comforted by a dummy but drains 7 oz bottles. He was previously only taking 6 oz and that wasn't every feed. He also can be difficult to settle after which has never been much of a problem before. He's noticeably grown this week. Is this a reaction to his jabs or a growth spurt? His consumption of milk during the day hasn't really changed. I've been lucky with his old fairly good sleep pattern and I'm hoping he will return to his old pattern. My husband has been off work this week but returns next week and he works very long hours. I've been lucky enough for him to take over in the mornings but I think I'm looking at a rather sleepless time ahead.
My daughters milk intake went up by 25% at 12 weeks old. Almost overnight she suddenly needed more frequent feeds and bigger feeds. This was a permanent change too, not just a 'growth spurt' that settles down.
So the key is to encourage most feeding to happen during the day, to avoid night feeds. Make a point of feeding baby more frequently through the daytime - every 2-2.5h and if bottles are being drained, start making bigger bottles.