New parents are often worried their baby isn’t getting enough milk. It’s hard to trust what you cannot see—there are no ounces listed on a breast! To make matters more confusing, some moms can only pump out a small amount of milk when clearly their babies—who are more efficient than a pump—are for sure drinking more.

Our pediatric advisor Dr. Alan Greene likes to tell parents that breastfeeding has worked for as far back as humans have existed and that bottles with ounce marks are a pretty new thing. “That there are so many people in the world is testimony that it does work,” he says.

Dr. Greene also makes the point that humans are designed with a great internal mechanism—in the mom as well as the baby—to tell if the baby is getting enough.

Still, the early days with a newborn can be nerve-wracking. Here is concrete evidence you can see to reassure you that your baby is getting enough breastmilk.

  1. Look for a satisfied baby. “If they are not getting enough, a healthy baby is usually not happy,” explains Dr. Greene.
  2. Look for wet diapers. “They should be having wet diapers at least every 8 hours at a few days old.”
  3. Look at their weight curve over time. “Day to day fluctuations are normal. Those early days a well-fed baby will usually gain about 5 to 7 ounces per week.”

Watching a baby’s weight does not mean you have to buy a baby scale and weigh your baby frequently at home, unless this is something you like doing and it will help you relax and enjoy nursing. Rest assured that well-baby visits are specifically designed to check baby’s weight at key moments and to catch a problem before it develops. “Measuring a bunch in between visits is generally not necessary,” says Dr. Greene.

If you’re feeling anxious and leaving your newborn pretty much constantly at your breast, that’s ok. In healthy babies there’s no such thing as too much breastmilk. “In general babies get just the right amount at just the right speed. There are a few unusual conditions where that mechanism is messed up but it’s rare,” says Dr. Greene. Breastfeeding is really set up so babies will get exactly what they need. “It’s an almost effortless thing.”

So take a deep breath. Chances are your baby is getting the perfect amount of breastmilk. If not, you will know. Truly.