--- title: "Feeding your baby: breast, formula or both" description: "Practical support for breastfeeding, formula and mixed feeding, with safe preparation and UK and US advice on vitamin D." url: "https://myruva.co/learn/feeding-your-baby-breast-formula-or-both" language: "en-GB" topic: "After a birth" published: "2026-10-18" updated: "2026-10-19" author: "Ruva team" reading_minutes: 4 --- # Feeding your baby: breast, formula or both Practical support for breastfeeding, formula and mixed feeding, with safe preparation and UK and US advice on vitamin D. *Written and reviewed by the Ruva team · Updated 2026-10-19 · After a birth* ## Key points - You can combine breastfeeding and bottle feeding. - Follow your baby’s signs that they’re hungry or full, rather than making them finish a bottle. - Advice on making up formula and on vitamin D for babies differs between the UK and US. You can combine breastfeeding with bottles of expressed milk or infant formula. Help with bottle feeding itself is available too. You can get support with whatever feeding plan you use, even if it changes. ## Start with the feed in front of you If breastfeeding hurts or feels hard, ask someone skilled in feeding to watch and help. In the UK, a midwife or health visitor can support you. In the US, a lactation consultant can help with breastfeeding. Tell them what you want help with. For bottle feeding, the NHS recommends first infant formula as your baby’s first formula. Follow the instructions for making it up carefully. If you’re worried about an allergy, talk to your baby’s doctor before changing to a special formula. ## Let your baby set the pace Offer a feed when your baby seems hungry. During a bottle feed, hold your baby close and fairly upright, supporting their head. Keep the bottle level, with a slight tilt, so the milk flows steadily. Let your baby take breaks, and stop when they’ve had enough. Your baby doesn’t have to finish the bottle. Never prop a bottle up or leave your baby to feed alone, because they can choke on the milk. Holding your baby, talking to them and looking at them can make bottle feeding a time to be close. ## Prepare powdered formula safely Wash your hands and clean the surface you’ll use. Use clean, sterilised feeding equipment. Measure the water first. Then add the exact amount of powder the container says, using the scoop that comes with it. Too much powder or water changes the feed, so stick to the amounts given. Advice differs between countries. In the UK, use fresh cold tap water and boil it. Let it cool for no more than 30 minutes, so it’s still at least 70C when you mix in the powder. Make each feed when you need it rather than making a batch. In the US, CDC usually advises following the container instructions using safe tap water. Some babies need extra care: those younger than 2 months, born early or with a weak immune system. For them, it advises boiling the water, waiting about five minutes, then mixing in the powder. These instructions differ from UK guidance. Cool the feed before giving it, and test it on your wrist. Never heat formula in a microwave, because it heats unevenly and can burn your baby. Throw away any formula left in the bottle after a feed. In the US, CDC advises using made-up formula within 2 hours of making it, and within one hour of starting a feed, whichever comes first. If you won’t start using it within 2 hours, put it in the fridge straight away and use it within 24 hours. Throw away any leftovers after a feed. ## Changing to mixed feeding Adding formula feeds can lower your breast milk supply. If you choose to start formula, doing it slowly gives your body time to adjust. It also makes painful swelling or mastitis less likely. Ask for support if you want to keep breastfeeding, breastfeed more, or work out how expressing fits into your plan. ## Vitamin D advice in the UK and US UK guidance recommends 8.5 to 10 micrograms of vitamin D a day from birth to 1 year for breastfed babies. Under NHS advice, babies having more than 500ml of infant formula a day don’t need a vitamin D supplement. US CDC guidance recommends 400 IU of vitamin D a day, starting soon after birth, for babies who have any breast milk, including mixed feeding. Babies who only have formula don’t need a supplement if they drink 32 ounces or more a day. Ask your health visitor, pharmacist or baby’s clinician about a suitable product, and follow the label. ## Ask for feeding support early Call 999 now (UK) or 911 (US), or your local emergency number, if your baby is hard to wake or has difficulty breathing. Contact your baby’s doctor urgently today (UK, US and elsewhere), or call NHS 111 in the UK, if your baby has fewer wet nappies than usual, seems unusually sleepy or has a sunken soft spot on their head. Don’t wait for a routine feeding appointment for these symptoms. Contact your midwife or health visitor in the UK, or your doctor or lactation consultant in the US and elsewhere, if pain is making you put off feeds or you’re worried about your supply. Ask for a feeding review and a chance to talk about your baby’s weight and growth. Bring a few notes about what happens during a feed and what you’d like to change. ## When to get help - **Emergency:** Call 999 now (UK) or 911 (US), or your local emergency number, if your baby is hard to wake or has difficulty breathing. - **Same day:** Contact your baby’s doctor urgently today (UK, US and elsewhere), or call NHS 111 in the UK, if your baby has fewer wet nappies than usual, seems unusually sleepy or has a sunken soft spot on their head. - **Book an appointment:** Ask your midwife or health visitor (UK), or your doctor or a lactation consultant (US and elsewhere), if feeding is painful or you’re worried about your milk supply. ## Where you live Services and advice differ between countries. - **UK:** NHS guidance says to use water that is at least 70C for powdered formula. Ask your health visitor about vitamin drops for your baby. - **US:** CDC advice on making up formula depends on your baby’s age and health. Breastfed and mixed-fed babies need vitamin D supplements. - **Elsewhere:** Elsewhere, ask your local baby feeding service about safe water, making up formula and vitamin supplements. Use the guidance for where you live. ## Sources 1. [How to combine breast and bottle feeding](https://www.nhs.uk/baby/breastfeeding-and-bottle-feeding/bottle-feeding/combine-breast-and-bottle/), NHS 2. [Bottle feeding advice](https://www.nhs.uk/baby/breastfeeding-and-bottle-feeding/bottle-feeding/advice/), NHS 3. [How to make up a feed](https://www.nhs.uk/best-start-in-life/baby/feeding-your-baby/bottle-feeding/how-to-make-up-a-feed/), NHS 4. [Infant Formula Preparation and Storage](https://www.cdc.gov/infant-toddler-nutrition/formula-feeding/preparation-and-storage.html), CDC 5. [Vitamins for children](https://www.nhs.uk/baby/weaning-and-feeding/vitamins-for-children/), NHS 6. [Vitamin D](https://www.cdc.gov/infant-toddler-nutrition/vitamins-minerals/vitamin-d.html), CDC 7. [Common breastfeeding challenges](https://womenshealth.gov/breastfeeding/breastfeeding-challenges/common-breastfeeding-challenges), Office on Women's Health 8. [Dehydration](https://www.nhs.uk/conditions/dehydration/), NHS --- This guide is general information to help you keep and use your own records. It isn’t medical advice. If you’re worried about a symptom, or something changes suddenly, talk to a doctor, nurse or pharmacist.