What’s the Deal with Bottle Nipple Flow Rates: Where to Start and When to Make a Change

Eliscia Wisner, OTR/L, CLC

This blog was written in paid partnership with Dr. Brown's.

When it comes to feeding your baby from a bottle, there are a few key features that can greatly influence feeding comfort, coordination and efficiency. One of the most overlooked — yet most impactful — is bottle nipple flow rate.

What is flow rate?

The flow rate of a bottle nipple refers to how quickly milk or formula passes through the nipple when a baby sucks. Most nipples are categorized by flow levels, commonly labeled as:

• Preemie or Ultra-Slow Flow
• Newborn or Slow Flow
• Medium Flow
• Fast Flow
• Variable or Y-Cut Flow

The ideal nipple flow is the one that allows your baby to feed both efficiently and comfortably. From a feeding therapist’s perspective, I look for a coordinated suck-swallow-breathe rhythm — typically close to a 1:1:1 pattern — feedings that last no more than 30 minutes, and a baby who appears calm, content and well-regulated throughout the experience.

Each brand has its own terminology and flow rate system, and unfortunately, there's no universal standard. That means one brand’s “slow flow” can be significantly different from another’s. Flow rates are also often paired with age-based guidelines, but it’s important to remember that those are just guidelines, not rules. The most reliable indicator of whether a flow is right? Your baby.

One brand that stands out for offering the widest variety of flow options is Dr. Brown’s, with choices ranging from Ultra-Preemie™ and Preemie Flow™, to Level T, Levels 1-4, and Y-Cut. This can be especially helpful for babies with unique feeding needs.

Why flow rate matters

The flow rate of a bottle nipple plays a critical role in every aspect of feeding. When the flow is too fast, babies may struggle with choking, coughing, gulping, or taking in excess air — all of which can lead to discomfort or even bottle refusal over time. Conversely, a flow that’s too slow may result in frustration, early fatigue, extended feeding sessions, or a baby who gives up before getting enough. 

Beyond just comfort, an appropriate flow rate supports:

• Efficient feeding
• Safe swallowing
• Proper oral-motor development
• Reduced air intake and gassiness

For most newborns or babies new to bottle feeding, it’s best to start with a slow flow nipple. This gives your baby time to coordinate sucking, swallowing, and breathing safely and effectively.

Babies who are primarily breastfed and are just beginning to take bottles also benefit from a slower flow, which mimics the effort required at the breast and reduces the risk of developing a bottle preference.

However, there are exceptions. If your baby is used to a strong letdown or is showing signs of frustration or impatience during bottle feeds, a slightly faster flow may be appropriate.

Some babies may benefit from extra-slow flows, such as Dr. Brown’s Ultra-Preemie™ or Preemie Flow™ nipples. These are especially helpful for:

• Premature babies
• Babies with low muscle tone
• Babies with reflux or respiratory challenges
• Babies with poor coordination or cardiac concerns

When to make a change

There’s no universal timeline for moving up flow levels. I always recommend starting slow and adjusting based on your baby’s cues — not their age.

If your baby is doing well with their current flow, there’s no need to switch. Watch your baby for signs that the flow might be too fast or too slow.

Signs the flow may be too fast:

• Gulping or chugging during feeds
• Choking, gagging or frequent coughing
• Milk leaking from the sides of the mouth
• Wide, alarmed eyes during feeding
• Fussiness or pulling away from the bottle
• Large spit-ups shortly after feeds
• Short, frantic feeds or feed refusal

Signs the flow may be too slow:

• Multiple sucks per swallow
• Feedings last longer than five minutes per ounce
• Fatigue or falling asleep mid-feed
• Sucking in air between swallows
• Chewing or compressing the nipple
• Fussiness or disinterest during feeding

If you try adjusting the flow and your baby still seems to struggle, it may indicate an underlying feeding coordination issue. In these cases, a feeding assessment with a qualified specialist can be incredibly helpful.

Final Thoughts

The “right” nipple flow rate is the one that allows your baby to feed safely, efficiently, and comfortably. Every baby is different — some will do well remaining on a slower flow, while others benefit from increasing. Your baby’s cues are your best guide.

If you find yourself having difficulty finding what is right for your baby or feeling unsure, consider reaching out to a professional trained in infant feeding. The right support can make a world of difference in your baby’s feeding journey.