Milk is usually part of a bedtime routine for most toddlers, and is perfectly fine if they finish the bottle, have their teeth brushed and then are put into their cot or bed to settle afterwards.
However taking a bottle of milk into the bed is not recommended for toddlers for a variety of reasons. These include the higher likelihood of tooth decay, as the warm milk is coating their teeth then staying there all night; also drinking milk in the cot when settling can become a difficult sleep habit that your child then thinks they cannot do without. Plus it makes for very wet nappies that can wake your child up later in the night if they leak, or if the nappy becomes really cold with the volume of fluid. Try to have a bedtime routine that involves the milk part before a story, so there is time to brush your little ones’ teeth, and then have a cuddle and bedtime book.
If your child is currently reliant on a bottle in the cot to settle to sleep, reduce the strength and volume of the milk over 4-7 nights until you are offering only a small amount of water. It is unlikely your child will be as hooked on water as they are on milk, so this can be completely discontinued after another night or two. Mostly, by the time you have got down to just a small amount of water, your child has gradually learned not to rely on the drink and you will see they start to settle more and more easily without it. You may wish to introduce a sleep toy at the same time that you reduce the milk, so your child is transitioning their comfort needs to the toy and away from milk in bed… this often makes it easier to get rid of the bottle anyway! Be sure that if your toddler has a sleep toy, that it is soft and safe, check it regularly and keep it for sleep times only.
Keep a calm, relaxing and predictable bedtime ritual, with just one or two non-stimulating bedtime books to read in your child’s room just before putting your toddler in the cot or bed following cuddles and kiss goodnight.