With my two babies I sometimes changed at just the right moment before they even showed any signs of needing to and it was seamless.

This will vary depending on the manufacturer – as there is no industry standard for teat sizes. When should I change from medium to fast flow teats? Hurley, K. M., Cross, M. B., & Hughes, S. O. (2011). A systematic review of responsive feeding and child obesity in high-income countries. The Journal of nutrition, 141(3), 495–501. https://doi.org/10.3945/jn.110.130047 [Accessed 6 December 2021] Appropriate if your child has shown consistent feeding with no difficulties and is taking larger amounts at the breast and bottle. This will depend on how frequently you’re planning to use bottles to feed your baby. Newborn babies generally feed between 10 and 14 times in 24 hours, with feeds becoming a little less frequent as they grow. If you are exclusively bottle feeding your baby, whether formula or expressed breastmilk, you might want around four to six bottles and teats to get you started. This allows for sterilising them between feeds.

I noticed with both teats and breast pump parts, such as filters, how the plastic seems to just degrade over time. As a baby’s feeding develops and they are taking a longer time feeding from a Level 3 teat, many parents choose to move up to a Level 4 teat.

Kimata, H. (2004), Latex allergy in infants younger than 1 year. Clinical & Experimental Allergy, 34: 1910-1915. Available at doi: 10.1111/j.1365-2222.2004.02128.x After this experience, I decided after reading online that many babies don’t need to increase the teat size that he must be ones of those babies, but then, not long later, Dexter started displaying a few key signs that he was indeed ready to move up to a faster flowing teat. NHS (2019b) Sterilising Baby Bottles, Available at https://www.nhs.uk/conditions/baby/breastfeeding-and-bottle-feeding/bottle-feeding/sterilising-baby-bottles/ [Accessed 3 December 2021]Powdered formula is not sterile, so you need to use water at approximately 70 degrees to kill any bacteria that might be present (NHS, 2019a). If the water is too hot it can reduce the nutritional benefit of the powder, but if it is too cold it may not kill the bacteria in the powder. ‘Ready-to-feed’ bottles contain ready-made milk that has already been sterilised (NHS, 2018; Unicef, 2019).