Supporting Combination Feeding in Clinical Practice: An Evidence-Based, Parent-Centred Approach for Healthcare Professionals

Milk production is regulated through a supply and demand mechanism; the frequency and effectiveness of milk removal from the breast stimulates ongoing milk production. Prolactin receptor activity is highest in the early postpartum period, and regular milk removal during this time is critical for establishing long-term supply. When milk remains in the breast for prolonged periods, feedback inhibitors reduce the amount of milk being made, leading to a gradual decline in production.

The introduction of infant formula can, therefore, influence milk supply when formula feeds replace breastfeeds without corresponding breast stimulation. Healthcare professionals have a responsibility to explain this mechanism clearly and neutrally, enabling parents to make informed decisions about feeding patterns while avoiding language that implies blame or failure.

For parents who wish to maintain or protect breastmilk production while combination feeding, regular expression at times when formula is given can support continued prolactin signalling. Expression may be achieved through hand expression or pumping, depending on individual circumstances and preference. It is important that this guidance is framed as supportive information rather than prescriptive instruction, in line with the Baby Friendly Initiative Standards emphasis on informed choice and personalised care (UNICEF, 2025).

From a professional and regulatory perspective, it is essential that discussions of milk supply do not imply that infant formula is equivalent to breastmilk in biological function. In line with EU food regulations, communications by healthcare professionals must clearly distinguish breastmilk from breastmilk substitutes and must not idealise or promote formula use (European Commission, 2015).

Evidence and clinical consensus suggest that delaying the introduction of bottles until breastfeeding is well established, often around three to six weeks postpartum, may reduce the likelihood of feeding difficulties related to latch, flow preference or reduced milk transfer at the breast (Kellams et al, 2017). During this period, infants are developing oral motor coordination and maternal milk production is still being calibrated.

Where earlier introduction of bottles is clinically or psychosocially indicated, additional professional support is required. This includes guidance on bottle feeding techniques that support infant self-regulation and protect breastfeeding. Responsive bottle feeding, also described as paced or cue-based feeding, aligns with Baby Friendly Initiative Standards (UNICEF, 2025) and is recognised by both the NHS and HSE as best practice when bottle feeding is used.

Responsive feeding involves recognising and responding to an infant’s hunger and satiety cues rather than feeding by the clock or aiming for a set volume. Paced feeding is a key component of responsive practice and helps to mirror the natural rhythm of breastfeeding. Holding the infant in a more upright position, offering the teat gently and allowing regular pauses prevents milk from flowing too quickly and gives the infant time to respond to feelings of hunger and fullness. This approach supports comfort and digestion and is particularly important for infants who are combination fed, as it reduces the risk of flow preference and helps protect breastfeeding (Kassing, 2002).

Infant formula powder is not sterile and therefore maintaining high hygiene standards when preparing bottles and feeding infants is essential, as babies have immature immune systems and are highly susceptible to infections. Proper sterilisation of feeding equipment helps prevent gastrointestinal illness and serious infections, including those caused by Salmonella and Cronobacter (the latter poses a particular risk to premature, low birthweight and immunocompromised infants).

Sterilisation methods vary in approach, convenience and cost. Boiling bottles in water for at least 5 minutes remains a simple, effective and chemical-free method. Steam sterilisers, whether electric or microwave, provide rapid sterilisation for multiple bottles at once, although care is required to avoid burns and to manage mineral build-up. Cold-water chemical sterilisation offers a portable and cost-effective option, particularly when travelling, but requires accurate dilution and daily solution changes to remain effective. Ultraviolet sterilisation systems are available, however, current evidence is limited and they are not routinely recommended by the NHS.

Regardless of the sterilisation method used, all bottles, teats and accessories must be thoroughly cleaned with hot, soapy water before sterilisation. Bottles and feeding equipment should be replaced if they become cracked, cloudy or discoloured, or if measurement markings are no longer clear. Teats deteriorate more rapidly than bottles, particularly during teething, and should be replaced regularly or sooner if damaged. New teats should always be used for each infant, especially when bottles are reused or obtained second-hand.

In the UK and Ireland, national guidance recommends sterilising all feeding equipment for at least the first 12 months of life. Sterilisation is particularly important when feeding premature infants, infants who are unwell, or when handling expressed breastmilk for donation to milk banks.

Common causes of ineffective sterilisation include inadequate pre-cleaning, overloading sterilisers, insufficient contact time and incorrect use of chemical solutions. Sterilised equipment remains safe for use for up to 24 hours if kept sealed within the steriliser or solution. When away from home, boiling or cold-water sterilisation methods are often the most practical options. Consistent hand hygiene and thorough cleaning before sterilisation remain essential components of infection prevention.

In practice, the choice of sterilisation method should take account of the family’s routine, resources and the infant’s clinical needs. Consistent sterilisation of clean, intact equipment supports safe feeding, minimises infection risk and helps build parental confidence.

The Baby Friendly Initiative Standards (UNICEF, 2025) emphasise that all parents, regardless of feeding method, should be supported with accurate, unbiased information and treated with dignity and respect. Responsive, cue-led feeding and caregiver sensitivity are widely recognised as supportive of infant wellbeing across feeding contexts.

In Ireland, the National Maternity Strategy 2016-2026 (Department of Health, 2016) commits to woman-centred, evidence-based care that respects informed choice and shared decision-making. Within this framework, infant feeding support should acknowledge the realities of families’ lives while ensuring that breastfeeding is protected and promoted at a population level.

The International Code of Marketing of Breastmilk Substitutes (World Health Organization, 1981) provides an ethical foundation for practice by restricting the promotion of infant formula and related products. Healthcare professionals must ensure that information about formula is provided when necessary, presented objectively and without commercial influence. Adherence to the Code protects families from marketing pressures and preserves trust in health services.

Parents may choose combination feeding for many reasons, including physical recovery, mental health, previous feeding experiences, social support or return to paid employment. These decisions are often emotionally complex. Healthcare professionals should adopt a non-judgemental, empathic manner that validates parental experiences while providing evidence-based guidance.

Language that implies hierarchy or moral value between feeding methods can undermine confidence and contribute to guilt or distress. In line with Baby Friendly Initiative Standards, discussions should focus on safety, responsiveness and parental goals rather than prescriptive feeding outcomes.

Common concerns in combination feeding include perceived low milk supply and infant refusal of the bottle or breast. Assessment should be grounded in objective indicators such as infant growth, output and feeding behaviour, rather than assumptions based on feeding frequency or infant temperament. Where challenges persist, referral to an International Board Certified Lactation Consultant or specialist breastfeeding support service is appropriate and aligns with best practice in the UK and Ireland.

Combination feeding is frequently introduced or adapted during transitional periods, particularly returning to work. Planning this transition several weeks in advance may support infants to adapt to alternative feeding methods and enable parents to establish expression routines if they wish to continue breastfeeding. Evidence shows that organisation policy, lactation spaces, protected expression breaks and milk storage facilities are key strategies to support breastfeeding practices (Vilar-Compte et al, 2021).

For infants over six months of age, the introduction of complementary foods provides an opportunity to encourage the use of a free-flow cup for fluids as part of complementary feeding, rather than introducing a bottle. This approach supports the development of oral motor skills, can be incorporated into responsive feeding practices, and is encouraged in national guidance in the UK and Ireland.

Healthcare professionals should remain familiar with current, evidence-based resources. In the UK, NHS guidance (2023) on combination feeding offers practical support, aligned with Baby Friendly Initiative Standards. In Ireland, mychild.ie provides parent-facing information on breastfeeding and formula feeding aligned with national guidance. For complex cases, referral to International Board Certified Lactation Consultants, community breastfeeding groups or specialist services ensures continuity and individualised care.

Combination feeding is a common infant feeding approach that requires skilled, compassionate and evidence-based support. By understanding lactation physiology, promoting responsive feeding, ensuring safe preparation practices and working within established ethical and regulatory frameworks, healthcare professionals can support parental choice while protecting the breastfeeding relationship.