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Avent Bottles: Different Models Explained
on January 16, 2011
Philips has done a fantastic job of confusing their line of Avent baby feeding bottles. It should be a simple matter to clearly name and describe a product such as this, but the reality is Philips has done it's best to complicate it.
Why the confusion: Over the past 25 years Philips has changes the Avent product line every year. Recently changes involved removing BPA from all parts that touch baby food (note that their products aren't 100% BPA free - parts that don't touch baby food may still contain BPA). This change introduced problems with some of the products causing the Avent venting system to leak (more on this later). In addition, Philips has used different product names for the same or similar products.
ISN'T A BOTTLE JUST A BOTTLE?
Recently Philips has made Avent bottles in several plastic materials:
1. Polycarbonate: this is a very hard and very clear plastic - it's properties closely match real glass and is commonly known by the brand name Lexan. For years almost all hard/clear food containers were made of polycarbonate plastic. Unfortunately, this type of plastic contains Bisphenol A (BPA) - which has been classified as a toxic substance in Europe and Canada (with the USA having serious concerns). Since 2008 manufacturers of almost all baby products have started to replace Polycarbonate with alternatives.
2. Polyethersulfone (PES): This rigid BPA free plastic hasn't traditionally been used in baby products because of the higher cost of the raw material. In addition, PES bottles typically have a brown or "honey" colored or brown tint - which may be unattractive to some parents.
2. Polypropylene (PP): Also a BPA free plastic, Polypropylene is slightly cloudy or milky in appearance. Containers made from Polypropylene are also slightly flexible.
Avent bottles are currently available in PES and PP models. Many people still have the old Polycarbonate bottles which perform great (but contain BPA).
LEAKS LEAKS LEAKS (AND THE MYSTERY OF THE "ADAPTER RING")
Many people have reported leaking problems with the newer Avent bottles. There are a couple of factors why this is happening:
The Avent system is designed to vent or let air into the bottle as baby feeds. This is achieved by having tiny slots cut into the base of the nipple. When baby sucks the nipple, it flexes and allows air into the venting slots (and then into the bottle). The benefit of this system is there are no special parts (see the Dr. Browns system) - so it's easy to clean and maintain. The disadvantage is this system relies on the interface/connection between the bottle and nipple - any problems where these two parts meet will cause leaks.
Many people have had issues maintaining a good connection between bottle and nipple with the PES (honey colored) bottles. This may be due to the bottle changing shape over time (particularly the impact of dishwasher washing).
The polypropylene bottles have a different issue. Polypropylene is simply too flexible to maintain good contact between the nipple and bottle. Philips has solved this problem redesigning the shape of the bottle and including a ridged "Adapter Ring" with recent polypropylene bottles (I think that first generation PP kits did not have this part). The adapter ring fits onto the top of the bottle and provides a stable and strong base needed by the Avent nipples. The new bottle shape with the adapter ring installed mimics the size and shape of the old style bottle. It's a hassle, but this extra part will prevent leaks if used properly. The ring also appears to be less susceptible to warping from high heat. You can purchase spare adapter rings separately.
Important: to prevent leaks you should assemble the bottle with nipple and adapter ring in place while it is wet! (read the manual).
CLASSIC VS ADVANCED VS NATURAL FEEDING VS EXTRA DURABLE
Philips seems confused with how to market Avent bottles. They have changed the name of Avent products over time and haven't done a good job differentiating between the polypropylene and PES bottles.
Some Avent bottles are branded CLASSIC and ADVANCED. The "Classic" bottles are the milky colored, softer plastic, polypropylene (PP) bottles which use the adapter ring - these are typically sold in a BLUE/WHITE BOX. The "Advanced" bottles are the honey colored, rigid plastic, polyethersulfone (PES) bottles - these are sold in a YELLOW/WHITE BOX.
Recently all Avent bottles have been branded NATURAL FEEDING - this additional name does not indicate which type of plastic the bottles are made of.
SO PES OR PP?
After trying both, I think I'll be using the Polypropylene (PP). At first I thought the adapter ring was a step backward - why do I want to deal with the extra part? But in practice it isn't much of a hassle at all. In addition, many people have reported leaks with the PES bottles. In addition, the PES bottles were less expensive (when I bought them).
Remember to assemble your bottles properly (wet) and do not over tighten them.
SHOPPING ON AMAZON
Make sure you know which type of bottle you are getting. Unfortunately, the Amazon product descriptions for Avent bottles don't always indicate which type of bottle you are getting. Philips makes most sizes of the Avent bottle in both types of plastic. Read the product description carefully before buying. Be cautious with reviews as some reviewers have written reviews for the other plastic type.
It is becoming harder to get anything but the "classic" (blue box) polypropylene (pp) bottles as it appears Phillips has recently withdrawn available inventories of all other bottles (i was talking to the manager of a local baby store who indicated they had to remove all Avent PES bottles and return them to Phillips). Still check to make sure you are getting the type of bottles you expect.
UPDATE 2 - June 2011
I still see old PES bottles for sale but they are almost completely gone. The "classic" polypropylene (pp) bottles are now available in blue and pink tints. Another recent change - recently manufactured bottles have a slightly wider mouth - you can tell if you have this new generation of bottles if the adapter ring does not fit snuggly (and will not stay in the bottle if held upside down).
Some people have ask what size nipples are included in the sets. 9 ounce bottle sets come with #2 nipples. 4 ounce bottle sets come with #1 nipples.