Glass vs. Plastic Baby Bottles

Medically Reviewed by Jabeen Begum, MD on September 26, 2023
7 min read

Decades ago, the only baby bottles you could buy were made of glass. But glass was heavy and breakable. So, when plastic bottles came along that were lighter and shatter-proof, the glass bottle became almost obsolete.

But reports that a type of plastic found in baby bottles might cause potentially harmful changes in developing babies left parents wondering if perhaps old-fashioned glass wasn't such a bad thing after all. These days, there are several types of bottles available, including hybrids that are a bit of both.

Here is some background on baby bottles, along with tips on how to choose – and use – bottles safely and effectively.

How many baby bottles do I need?

Once you pick a specific bottle, buy at least a dozen of them. Even if you’ll be breastfeeding, you may want some extra baby bottles for pumped breast milk storage.

When deciding which type of bottle to use, ask for advice from friends, family, or your baby’s doctor. Try different things, and test a few to see which you and your baby like best. There are basically five types of baby bottles:

Glass baby bottles

This type of bottle is heavy yet sturdy. 

Pros: They last a long time, and you can boil them for a deep clean.

Cons: They’re heavier than plastic and may shatter if you drop them.

Plastic baby bottles

These are baby bottles made out of a plastic called polypropylene.

Pros: They’re lightweight, strong, and not easily destroyed.

Cons: Plastic baby bottles may not last as long as glass. And if you’re using older, secondhand bottles, they may have bisphenol A (BPA), a chemical used to make hardened plastic. The FDA banned the use of BPA in 2012 from baby bottles and sippy cups, but older ones may have it.

The ban on BPA means you can buy new plastic baby bottles with confidence that they’re free of the potentially harmful chemical. If you’re using older plastic bottles (for example, bottles given to you by family members), check the recycling symbol on the bottom. The symbol #7 or the label PC (which stands for polycarbonate) is a sign that the bottle likely contains BPA. Bottles with the symbol #1, #2, or #4 are made of polyethylene, and #5 bottles are made of polypropylene. Both kinds of bottles can be used safely since neither type contains BPA.

Disposable bottle liners are also typically BPA-free (look for the words "BPA-free" on the label). They tend to be more expensive than bottles alone, though, because you have to change them after each feeding.

Even BPA-free plastic bottles could have some risks. Some studies have found that polypropylene bottles shed tiny plastic particles, called microparticles. But so far, there's no scientific evidence that they're harmful.  

Hybrid baby bottles

Hybrid bottles have a glass liner to stop chemicals from coming into contact with the formula, with a plastic outside that keeps them from breaking. If you want to try glass bottles but you're concerned about them breaking, some companies make silicone sleeves that go over the bottle to protect it.

Pros: They're lightweight, safe, and won't discolor or retain bad smells. 

Cons: They may be more expensive than plastic or glass.

Stainless steel baby bottles

This type of bottle is plastic-free.

Pros: Strong and can’t be broken 

Cons: More expensive 

Disposable baby bottles

These are usually made out of weak plastic or paper material and are meant to be used just once. 

Pros: These reusable plastic bottles have a disposable sterilized liner for each feeding. They’re convenient because cleanup is quick.

Cons: The disposable inserts may not be great for the environment, and the bottles are usually more expensive than plastic or glass. You also need to keep a supply of liners on hand, which can be costly. 

You can buy several shapes and sizes of baby bottles, including: 

Standard bottles

These bottles have straight sides or ones that curve a bit. It’s simple to fill and clean them, and you can clearly see the level of liquid left in the bottle.

Vented bottles

They let out air to reduce the number of air bubbles. It’s thought that vented air bottles ward off colic and gas, but there’s not enough evidence to know for sure. They also have more parts to clean and assemble.

Wide bottles

These short, wide-mouth bottles are designed to mimic a breast. They’re for babies who use both bottle and breast.

Angle-neck bottles

These bottles are easier to hold and help stop babies from swallowing air. But filling them can be tricky. You’ll need a funnel or sideways grip to refill them.

Nipples for baby bottles are usually made of two types of materials:

  • Latex. This kind of nipple is soft and pliant. But it may wear down more quickly. Also, some babies can have a reaction to latex.
  • Silicone. Nipples made of silicone are more durable and keep their shape better than latex.

Baby bottle nipples can be rounded, wide, flat, or shaped to mimic the feel of a nipple. Depending on the size of the nipple hole, they also have different flow rates. Here’s a closer look at each shape:

  • Orthodontic-type nipples. These are long, with a shape designed to seem like your nipple when your baby is feeding. Be sure your little one latches onto the section of the nipple that’s wide and flat.
  • Nubbin nipples. These have short, flattened tips. You’ll often pair them with bottles that use disposable liners. But some babies may find them hard to grasp, especially if they breastfeed, too.
  • Standard nipples. These are easy-to-use nipples with a long, rounded tip.
  • Tri-cut-type nipples. Longer than a standard nipple, tri-cut nipples come the closest to the feel of a breast nipple. Because they’re longer, they release milk deeper into your baby’s mouth, which helps with swallowing.

As with bottles, your baby may prefer a certain nipple type. The only way to find out is to try them. To get started, ask friends, family, and your baby’s doctor which types and brands they suggest.

Get at least 12 nipples and covers. Keep in mind that nipples crack and leak with use, so you’ll likely need to buy more over time. And the sizes will change as Baby grows.

A baby bottle warmer is a device that quickly and evenly warms your baby’s bottle of milk. It works to circulate the milk nonstop, which helps to avoid "hot spots" – areas in which the liquid is very hot – you can get when using a microwave. It’s also more convenient than submerging a bottle in water to warm. 

Still, be careful when using bottle warmers. Follow the manufacturer's directions exactly and keep the warmer out of the reach of other children. Remember that formula and breast milk don't need to be warmed, though some babies prefer it.  

Baby bottle drying rack

A baby bottle drying rack keeps bottles and other related items organized and out of the way while they dry. Some have an open design, which helps air to circulate and water to dry up.

You’ll need to sterilize your baby’s bottles and nipples before using them for the first time. If you're using plastic bottles, follow the manufacturer's directions for sterilizing them. 

To sterilize glass and other heat-safe bottles: 

  • Put them in a pan and make sure they’re completely covered with water. 
  • Let the water come to a boil, and boil the nipples and bottles for 5 minutes.
  • Then, use soap and water to wash them.
  • Let them air dry.

There’s lots of gear to choose from, including brushes, carrying cases, sterilizers, and dishwasher bottle baskets.

Pediatricians and parents usually agree that these items are helpful:

  • 1 baby bottle brush
  • 1 nipple brush
  • 6-12 bibs
  • 1 breast pump with storage bottles (if you’re breastfeeding)
  • 12 burp cloths, receiving blankets, or clean cloth diapers

1. Don’t sterilize glass baby bottles and nipples before every use. That practice was only necessary in the past when local water supplies weren't as reliably clean as they are now.

You can wash bottles in the dishwasher, which cleans better than hand-washing them. Or wash them by hand with hot, soapy water and rinse well. (Some plastic bottles may also be dishwasher safe; see the manufacturer's instructions.)

2. Do replace baby bottles and nipples if you find that a certain set doesn’t suit your baby’s needs.

3. Do replace a glass baby bottle if it’s cracked or chipped.

4. Do replace a plastic baby bottle if it’s cracked, leaks, is discolored, or smells bad.

5. Do replace a nipple if it’s discolored or isn't in good shape (a damaged nipple can be a choking hazard), or if milk comes out too fast.

To test the flow, turn the bottle upside down. Only a few drops should come out. If you see more, the hole is too big, and your baby may get more formula or breast milk than they can handle. Nipple packages should state the flow rate on them.

6. Do label breast milk bottles for storage.

7. Don't store breast milk or formula in plastic bottles. Pour it into the bottle just before your baby is ready to eat. Throw out anything that is left over.

8. Don't use hot water or a harsh cleaner on polycarbonate bottles, because this can cause the plastic to break down more quickly. Instead, use a gentle cleaner and warm water.