Most babies have a growth spurt around 4 months and 6 months. I say "most," because babies can stick to their own timetables, but they will experience them around this time regardless. They will usually last for 2-3 days and you will notice that your little one has become more fussy, is sleeping less, possibly sleeping more, and is likely nursing more than ever.
According to supply and demand, your milk supply will increase the more that your baby nurses. It’s not recommended that you supplement with formula or express milk during these times because it can affect your supply. That being said, it can be a stressful time for mom when she feels like her baby may not be getting enough nutrition.
When my daughter was going through her 4-month growth spurt (which seemed to last A LOT longer than 3 days) I felt I had a difficult time keeping my supply at pace with her needs. She never seemed to get enough milk at night and I wish I had been more prepared for the growth spurt in that maybe having had some lactation bars on hand or knowing that it wasn’t my milk supply at all that was dwindling, just that her needs were increasing. My daughter nursed herself to sleep (and still does at 13 months) which I have since learned is a blessing and a curse. For one, it provides them with so much comfort and it also helps to keep your supply up, but it also puts a lot of strain on mama when she is the only one who can soothe baby back to sleep.
Concerning sleep, there are some babies that might sleep more through the night because growing little bodies takes a lot of energy! But, others respond to growth with fitful sleep. If baby is having a difficult time and it’s been less than a couple hours since the last feeding, you can try going down the checklist of making sure they have clean diaper, re-swaddling, putting on white noise, or shushing them back to sleep. Another thing to be prepared for is frequent wake-ups during the night, even from the very best of sleepers. Though it is exhausting, just know that it is temporary and there is a great chance they will get back to their sleep routine once the growth spurt has passed.
Lisa is a babywearing, breastfeeding, cloth diapering mama that had a little one who definitely made sure to keep her supply up through the wee hours of the night.