Short answer: If you can, wait until breastfeeding is going well — often a few weeks — before regularly offering bottles. Express by hand or with a pump, store milk in the back of the fridge for up to 8 days at 4 °C or lower, or freeze it for up to 6 months. If you add formula, do it gradually to protect your supply and avoid uncomfortably full breasts. Combination feeding isn't a half-measure; for many families it's exactly the right solution.
At some point, “I'd love a few hours out” runs into the fact that you're the only one carrying the food. Expressing and combination feeding can solve that. It just takes a bit more organising than the leaflet suggests.
When to start
It can take several weeks for you and your baby to feel confident with breastfeeding. Once you have, it's usually possible to offer bottles of expressed milk or formula alongside breastfeeding. If you're going back to work, start a few weeks beforehand so you both have time to adjust.
Expressing a little after a morning feed, when many people feel fullest, is a common way to start building a small store without taking milk your baby needs at the next feed.
Hand expressing or a pump?
- Hand expressing needs no equipment and is useful in the early days, for engorgement or a blocked duct. Your midwife or health visitor can show you how.
- Manual pumps are cheaper but slower.
- Electric pumps are quicker; in some areas you can hire one. Build up the suction slowly — starting high can hurt or damage your nipple — and make sure the funnel fits. A pump should never bruise or pull your nipple painfully into the funnel.
Clean and sterilise the pump parts and containers before each use. Having your baby, or a photo of them, nearby can help your milk flow.
How long breast milk keeps
- Fridge (at the back, not the door): up to 8 days at 4 °C or lower. If your fridge is warmer (5–10 °C) or you're not sure, use it within 3 days.
- Ice compartment of a fridge: up to 2 weeks.
- Freezer at −18 °C or lower: up to 6 months.
- Cool bag with ice packs: chilled milk can be carried for up to 24 hours.
Store milk in small amounts to avoid waste, and label and date anything you freeze. Defrost slowly in the fridge, or in a jug of warm water if you need it straight away, and don't refreeze it. Once your baby has drunk from a bottle, use it within an hour and throw the rest away. Never warm or defrost breast milk in a microwave: it can create hot spots that burn your baby's mouth.
Milk that has separated into layers hasn't gone off. The fat simply rises; a gentle swirl mixes it again.
Introducing the bottle
- Offer the first bottles when your baby is calm and relaxed, not very hungry.
- It may help if someone else gives the first few bottles, so your baby isn't close to you and smelling your milk.
- Try a different position from the one you use for breastfeeding.
- Many breastfeeding supporters suggest a slow-flow teat and letting your baby take breaks, so feeding from a bottle isn't much easier than from the breast.
- From around six months, a cup can be an alternative to a bottle altogether.
Combining breast and formula
Combination feeding means your baby has some breastfeeds and some bottles of formula. A few things help it go smoothly:
- Go gradually. Replacing feeds slowly gives your body time to make less milk and lowers the chance of swollen, painful breasts or mastitis.
- Protect your supply. Every feed replaced by formula tells your body to make a little less. If you want to keep your supply up, express around the time your baby has a bottle.
- Use first infant formula in the first year, made up exactly as the instructions say.
- Want to breastfeed more again? Lots of skin-to-skin contact, frequent feeds and regular expressing (about 8 times a day, including once at night) can help. Ask a breastfeeding supporter for help.
Expressing at work
Your rights depend on where you live:
- UK: employers must provide a suitable place for breastfeeding employees to rest. It should be hygienic and private so you can express milk — toilets aren't suitable — and ideally include somewhere to store milk, such as a fridge.
- US: under federal law, most nursing employees are entitled to reasonable break time and a private space, other than a bathroom, to express milk for up to one year after their baby's birth.
- Elsewhere: many countries, including several in the EU, give paid breaks or reduced hours for breastfeeding. Check your national rules or ask HR.
Talk to your employer before you return, so the space and timing are sorted in advance.
Expressing is extra work on top of work. If it becomes too much, you can stop. That's a choice, not a failure.
When to get help
If your supply seems to be dropping, expressing hurts, or your baby refuses the bottle for weeks, a breastfeeding specialist can often spot the problem in one session — the pump setting, the funnel size or the timing. In the UK, the National Breastfeeding Helpline is open 24 hours a day on 0300 100 0212.
Related reading
- Starting breastfeeding: the first week
- Engorgement, blocked ducts and mastitis
- Combining work and motherhood
More support: Breastfeeding with Confidence (PDF, English) takes you step by step through breastfeeding, including expressing.
Sources
- NHS — Expressing and storing breast milk.
- NHS — How to combine breast and bottle feeding.
- Health and Safety Executive (UK) — Rest and breastfeeding at work.
- U.S. Department of Labor — FLSA protections to pump at work.
Written by the Bloom Guides editorial team. Last updated: 19 October 2026. General information only — not a substitute for advice from your midwife, health visitor or doctor.