It’s something every parent experiences: Just when you’ve figured out your baby’s feeding pattern, they go and grow on you, and their needs change. (Actually, that’s a pretty good metaphor for parenting in general!) While growth spurt milestones can vary from child to child, growth spurts typically happen around 2-3 weeks, and then at 6 weeks, 3 months, and 6 months. At those times—and sometimes other times as well—your baby might require larger portions, or need to feed more frequently.

While your baby can’t verbally tell you they’re extra hungry, they can let you know with certain nonverbal cues and clues. Keep an eye out for these three signs, which might indicate your baby is ready to increase their formula or breastmilk intake. 

They’re giving you classic baby hunger cues

You know these signals by now: your baby is rooting (turning their head toward anything that strokes their cheek), they’re crying more than usual and are fussy even after a feeding, or they’re sucking on their fists or fingers. No matter how long it’s been since their last feeding, if you see these signs, offer them milk or formula.

They’re feeding more often

If your baby is showing their usual hunger signs soon after they last ate, it might mean they’re not getting enough breastmilk or formula at each feeding. When babies need to feed between every 30 minutes to an hour, it’s sometimes called cluster feeding. This may happen more at night, as they are filling their bellies in anticipation of sleep. If you’re breastfeeding, know that your body will respond to the additional milk demand. And if you’re formula feeding, be sure to keep enough on hand to meet your baby’s hunger needs. 

They aren’t gaining enough weight

Your pediatrician monitors your baby’s weight gain, and will let you know if they aren’t gaining enough. At that point, the doctor may recommend increasing baby’s formula or breastmilk intake. (When new mom Chrissy Horton found herself in a similar situation, she found a clever way to increase her baby’s nourishment with each feeding.)

Most experts advise feeding infants on demand, especially when they’re very young. If you’re at all concerned about how much to feed your baby, or want to be prepared for when they do experience an inevitable growth spurt, you could keep a feeding log: Track the timing, duration, and quantity of breastmilk or formula, if you have access to it. (If you’re breastfeeding, you might note how many minutes your baby spent on each breast.) Learning your baby’s feeding patterns can help you notice when and if they suddenly shift. 

Trust your instincts when it comes to your baby, and when in doubt, consult your doctor. As a parent, you have at least 18 years of gauging—and responding to—your child’s hunger ahead of you. You’ve got this!