Baby bottle nipples can be either latex or silicon. Latex nipples are golden brown, soft and a little more flexible than silicon nipples. Silicon nipples are clear, heat-resistant, and can be cleaned in the dishwasher. Silicon nipples are less porous and less prone to bacteria than latex nipples, and typically last 3-4 times longer. No matter what type of nipple you decide to use, be sure to check them regularly for cracks and other signs of deterioration. It is also best to use the nipple and the bottle collar that are the same brand as the bottles that you are using to ensure a proper fit and avoid leaks.

Nipples also come in six designs:

1. Naturally shaped nipples are soft with a wider base to promote proper latch-on and suckling to help baby transition between breastfeeding and bottle feeding. Avent Naturally and Playtex Ventaire are two examples of this type of nipple.

2. Orthodontic nipples have an irregular shape with an indent in the center. The nipple elongates after repeated sucking to resemble breastfeeding. This type of nipple may also be more comfortable on baby's gums, especially when teething. Playtex and Gerber are two examples of companies who offer an orthodontic nipple.

3. Traditional nipples are bell shaped with a thinner base and tip. Avent offer a nice traditional shaped nipple.

4. Anti-vacuum, or vented, nipples are designed with a tny hole to let air into the bottle as baby sucks on the nipple. The hole is meant to prevent the nipple from collapsing, and reduce the gas and discomfort that a baby struggling to get milk can experience. Dr. Brown's bottles are an example of this type.

5. Multi-flow nipples can be adjusted to give baby a slow, medium or fast flow. It will give you more flexibility in choosing the right flow for baby during feeding without having to change nipples.

6. Slotted multi-flow nipples are similar since they are also adjustable, but these feature slots instead of holes. These are ideal for cereal or thicker juices. You can turn the nipple to adjust the flow based on the thickness of that is in the bottle. Avent makes a variable flow nipple that is a perfect example of this.