Glossary of Key Terms

Below are explanations for some of the key terms used throughout this website resource:

Exclusive breastfeeding– The UK Department of Health and the World Health Organisation (WHO) recommend exclusive breastfeeding for the first six months of a baby’s life followed by breastfeeding alongside the introduction of complementary solid food1, 2, continuing to two years of age and beyond if desired by mother and baby2. Definitions of ‘exclusive breastfeeding’ vary in the literature, but in this website the intended definition is ‘no supplement of any kind including water while breastfeeding, excepting essential medicines’.

Mother-baby dyad– The term dyad can refer to two individuals regarded as a pair, involved in an ongoing interaction or relationship. GPIFN uses the term mother-baby dyad to illustrate the breastfeeding relationship and the unity between the two individuals, essential to both lives.

Breastfeeding Support– See our page on Breastfeeding Support for definitions of key roles including Infant Feeding Lead, Lactation Consultant (IBCLC), Breastfeeding Counsellor, Breastfeeding Peer Supporter, and Tongue-Tie Practitioner.

When we use the term ‘breastfeeding support’ without capitalisation it is used to imply practices which enable ongoing optimal breastfeeding, for those who wish to continue.

Responsive Breastfeeding– The term ‘responsive feeding’ replaces the term ‘demand feeding’ or ‘feeding on demand’. Responsive feeding describes a sensitive, reciprocal feeding relationship which provides nutrition and comfort for babies and promotes secure attachment. Responsive breastfeeding involves a mother breastfeeding according to her baby’s cues and as well as to her own desire to feed her baby. Healthy responsively breastfed babies will self-regulate their feeding and cannot be overfed or ‘spoiled’ by frequent feeding3.

Responsive/Paced Bottle Feeding– Parents need to take care to avoid overfeeding a bottle fed baby. Where a baby is healthy, offering a bottle in response to feeding cues, gently inviting the baby to take the teat, pacing the feeds and avoiding forcing the baby to finish the feed reduce this risk. Supporting parents to respond to their bottle fed baby’s feeding cues and hold their baby close during feeds can also help to promote secure attachment3.

Lactogenesis– In the context of the GPIFN website this refers to human breastmilk production. It can be considered in 3 distinct stages which are influenced by hormonal changes:

  • Lactogenesis I – differentiation of alveolar epithelial cells into lactocytes that secrete colostrum
  • Lactogenesis II – onset of copious milk secretion occurring between 32 and 96 hours postpartum
  • Lactogenesis III – maintenance of milk production

Galactagogue– A substance taken to increase milk supply. In addition to medications, certain herbs and foods may be described as galactagogues.

Complementary Foods-Any food suitable as a complement to breast milk or to infant formula, to be introduced once a child has achieved developmental readiness for solid foods. Such food is commonly called ‘weaning food’.

Introducing/Starting Solids– The terms ‘introducing solids’ or ‘starting solids’ are preferable to ‘weaning’ as the latter suggests that milk feeding should diminish and cease. Milk feeds should infact remain a significant part of an infant’s diet4.

Breastmilk Substitute– Any food or drink being marketed or presented as a partial or total replacement for breast milk, whether or not suitable for that purpose5.

Artificial Baby Milk- An artificial substitute for breastmilk intended for feeding infants. These may be obtained in powdered form or as ready-to-feed liquids.

Infant Formula– an artificial baby milk designed to be nutritionally adequate for exclusive feeding for infants under 6 months of age who are not breastfed, and suitable for use alongside complementary foods up to 12 months of age. These must comply with the UK regulations on infant formula.

‘Follow-on’ Formula– an artificial baby milk suitable for and marketed to be used only after 6 months of age alongside solid foods. These must comply with the UK regulations on ‘follow-on’ formula.

Infant Milks– As per First Steps Nutrition Trust, an term used for all milk-based drinks available commercially for infants and young children.

Specialised Milks/Foods for Special Medical Purposes (FSMPs)– Milks designed and marketed as suitable for infants with medical needs and covered by ‘foods for special medical purposes’ regulation, distinct from infant formula and ‘follow-on’ formula regulation. These should be used under medical supervision.

‘Ready-to feed’ Formula– pre-made, sealed bottles of formula which, in contrast to tubs/tins of powdered formula, are sterile until opened.

The Code (The WHO International Code of Marketing of Breast-milk Substitutes)5– Restricts the marketing of breastmilk substitutes to the public and health professionals in order to protect and promote breastfeeding and to ensure the proper use of breastmilk substitutes, when these are necessary.  The Code was ratified by the World Health Assembly in 1981, and incorporates subsequent World Health Assembly resolutions. It has been wholly or partly implemented as national law in several countries, including partially in the UK(See also our page on ‘The WHO Code‘).

The WHO International Code of Marketing of Breastmilk Substitutes (The Code) and subsequent World Health Assembly resolutions are global agreements aim to “contribute to the provision of safe and adequate nutrition for infants, by the protection and promotion of breastfeeding, and by ensuring the proper use of breastmilk substitutes, when these are necessary, on the basis of adequate information and through appropriate marketing and distribution”.  Nations can pass legislation to uphold the resolutions, but are not penalised if they do not do so.

The Baby Friendly Initiative (BFI)Worldwide programme of the World Health Organization and UNICEF to encourage maternity hospitals to implement the 10 Steps to Successful Breastfeeding and to practice in accordance with the International Code of Marketing of Breast-milk Substitutes (see above).  In the UK this is known as Unicef UK Baby Friendly Initiative.

Epigenetics– Heritable mechanisms in gene expression that do not involve changes to the underlying DNA sequence.  These include microRNAs, histone modifications and DNA methylation.

Microbiome- The microbiome is defined as the collective genomes of the microbes that live inside and on the human body. The ‘gut microbiome’ refers to the microbes colonising the human gut.

Prebiotics– Undigestible oligosaccharides which support the growth of potentially beneficial bacteria in the colon.


  1. UK Department of Health: Nutrition for Pregnancy and the Early Years – Breastfeeding June 2011
  2. WHO: Infant and Young Child Feeding Fact Sheet No 342 Updated February 2018
  3. Unicef UK Baby Friendly Initiative: Responsive Feeding Supporting Close and Loving Relationships
  4. Start4Life: What to Feed Your Baby
  5. WHO: The International Code of Marketing of Breastmilk Substitutes 1981
  6. UK Gov: The Infant Formula and Follow-on Formula (England) Regulations 2007

 Published April 2017, Updated August 7th 2019