Why is theCloser to Nature easi-ventteat collapsing when my baby is feeding?

The Closer to Nature easi-vent teat is very sensitive as it is made of specially designed silicone material which can sometimes stick the slits together when not used for periods of time. This is perfectly natural. If this occurs, you can reopen the slit at the tip of the tent like valve by gently manipulating the valve between your finger and thumb until you see the slit open. This allows the air to flow into the bottle, preventing the teat from collapsing.

The Closer to Nature advanced comfort bottle's round dome valve, which fits onto the bottom of the venting tube is also very sensitive as it is made of specially designed silicone material. This can also stick together at times when not used for periods of time. To ensure the slit in the dome valve is open before use, flush through with water, gently manipulating the valve between your finger and thumb until you see the slit re-open.

Another point to note is that your little one may want more milk than they are able to get.