A supplemental nursing system (SNS) is a device that delivers expressed breast milk or formula to a baby through a thin tube taped alongside the nipple, so the baby feeds from the breast and the tube at the same time. It solves two problems at once: the baby gets the nutrition they need right now, and the sucking stimulation tells the parent’s body to produce more milk. This makes it fundamentally different from bottle supplementation, which bypasses the breast entirely.
How the Device Works
The basic design is simple. A small bottle or reservoir hangs on a cord around the parent’s neck, positioned upside down above breast level. A thin flexible tube runs from the bottle down to the nipple, where it’s secured with medical-grade paper tape. When the baby latches onto the breast, they take both the nipple and the tip of the tube into their mouth. Each suck draws milk from the breast and supplement from the tube simultaneously.
You can tell the system is working correctly by watching for small bubbles rising into the bottle each time the baby sucks and swallows. The flow rate depends on how high the bottle is positioned relative to the baby (higher means faster flow) and the diameter of the tubing. Most commercial systems, like the Medela SNS, come with three tubing sizes: small, medium, and large. Starting with the smallest tube lets you match the flow to what a newborn would normally get from the breast, then increase as needed.
Why It Matters for Milk Production
Milk production runs on a supply-and-demand feedback loop. When a baby sucks at the breast, the body releases two key hormones: one triggers milk production, and the other triggers milk release (the “let-down” reflex). Research has confirmed that these hormonal responses simply don’t happen during bottle feeding. No suckling at the breast means no signal to make more milk.
This is the core advantage of an SNS over a bottle. Every feeding session doubles as a milk-production session. The baby stays nourished while the parent’s body receives consistent signals to ramp up supply. Over days and weeks, the goal is to gradually reduce the amount of supplement in the bottle as the breast produces more on its own.
Common Reasons for Using One
The most frequent reason is low milk supply. This can stem from hormonal conditions, breast surgery, certain medications, or simply a supply that hasn’t fully established yet in the early postpartum days. When a baby isn’t gaining weight adequately on breast milk alone, an SNS lets you supplement without pulling the baby off the breast.
Parents working on relactation (restarting milk production after a gap) also rely on the device. If breastfeeding stopped for medical reasons or a NICU stay, the SNS gives the baby a reason to latch and stay at the breast even when little or no milk is flowing yet. The consistent stimulation helps rebuild supply over time.
Adoptive parents and others pursuing induced lactation use an SNS as a central tool. The process typically involves weeks or months of preparation, including pumping with a hospital-grade pump and sometimes hormone therapy to mimic the breast changes of pregnancy. Once the baby arrives, the SNS bridges the gap between what the body can produce and what the baby needs, while keeping the baby at the breast to continue driving supply upward. Even with successful induced lactation, supplemental feedings are often necessary for the first several weeks.
The device is also used for babies who have difficulty transferring milk effectively due to a tongue tie, prematurity, or low muscle tone. These babies may latch but not generate enough suction to drain the breast well. The SNS ensures they get adequate volume while they develop stronger feeding skills.
What Comes in the Kit
A standard Medela SNS includes a feeding bottle with an attachment ring, a valve holder, three color-coded valves with tubing (red for small, white for medium, transparent for large), a cover, paper tape for securing the tube to the breast, and a neck cord. The bottle hangs from the cord, and you tape the tube so it ends right at the tip of the nipple. A piece of tape about 6 centimeters long is typically enough to hold the tube in place.
Some parents try the Haakaa supplemental feeding system as a less expensive alternative. It uses a simpler silicone design, but users have reported that the milk flow can be harder to control, often running too fast compared to the Medela version. Flow control matters because a tube that delivers milk too quickly can discourage the baby from actively sucking, which defeats the purpose of breast stimulation.
Getting the Latch Right
Positioning the tube correctly takes some practice. The tube should run along the top of the breast with the tip ending flush with or just past the end of the nipple. If the tube extends too far, it can trigger gagging. If it doesn’t extend far enough, the baby won’t be able to draw from it. Tape the tube to the breast about an inch or two back from the nipple so it stays in place but doesn’t interfere with the latch.
When latching the baby, bring them to the breast just as you would without the device, aiming the nipple toward the roof of their mouth. The baby should take in both the nipple and the tube tip in a wide, deep latch. Many parents find it easiest to get the baby latched first, then slide the tube into the corner of the baby’s mouth, though some prefer to have everything in position before latching. A lactation consultant can help you find the approach that works best for your situation.
The first few attempts often feel awkward. Taping a tube to your skin, getting a baby to latch around it, and managing a bottle of supplement while holding an infant is genuinely tricky. Most parents report that it becomes significantly easier after the first week or two of regular use.
Cleaning and Safety
Because the tubing is narrow and in direct contact with milk, thorough cleaning after every use is essential. Milk residue inside the tube can harbor bacteria quickly. Most manufacturers recommend flushing warm soapy water through the tubing immediately after feeding, then sterilizing according to the product instructions. Tubing that becomes cloudy, discolored, or difficult to clean should be replaced.
Some parents attempt to build homemade versions using syringe tubing or other makeshift materials. This carries real risks. Non-medical-grade tubing may leach chemicals, be impossible to clean thoroughly, or deliver milk at an uncontrolled rate. The FDA has warned broadly about contamination risks with improvised infant feeding setups. Commercial SNS devices are designed with food-safe materials and calibrated flow rates, and the cost, while not insignificant, is a worthwhile investment for safe feeding.
What to Realistically Expect
An SNS is not a quick fix. It’s a tool for a transitional period, and that period can last anywhere from a few days to several months depending on the underlying reason for use. Parents supplementing due to a temporary dip in supply after illness may wean off the device within a week or two. Those inducing lactation for the first time may use it for months, gradually decreasing the volume of supplement as their own production increases.
The emotional experience varies widely. Some parents find the device empowering because it lets them breastfeed when they otherwise couldn’t. Others find it frustrating, especially during nighttime feedings when taping a tube to your skin in the dark feels like an unreasonable ask. Both reactions are normal, and many parents describe feeling both on the same day. Having realistic expectations and support from a lactation professional makes a meaningful difference in whether the experience feels sustainable.