Breastfeeding: the complete guide

Breastfeeding is one of the most natural things in the world, and also one of the hardest things to start. Many parents are surprised by this. The mechanism is biological, but the skill takes time to develop — for both the parent and the baby.

This guide covers how breastfeeding works, how to get started, what to expect in the first weeks, and how to handle the most common challenges. For parents who are formula feeding or doing both, the overview starts at the Feeding your baby hub.

How breast milk production works

Milk production operates on supply and demand. The more milk is removed from the breast — by feeding, pumping, or hand expression — the more your body produces. The less that is removed, the less is made.

This mechanism is driven by prolactin, the hormone that stimulates milk production, and oxytocin, the hormone that causes the let-down reflex (the release of milk from the ducts). Prolactin levels rise after each feed and peak about 30 minutes later. Frequent, effective feeding in the early weeks is what establishes and protects supply.¹

The implication: supplementing with formula in the first weeks without also pumping or feeding at the same time will reduce supply, because the breast receives a signal that the milk was not needed. This is not a reason to avoid combination feeding when it is medically necessary or a parental choice — it is just the mechanism to understand.

Getting started: colostrum and the first days

Before mature milk arrives, your body produces colostrum — a thick, sticky, yellowish fluid rich in antibodies, white blood cells, and concentrated nutrients. It is present from late pregnancy and produced in small volumes (5–7 ml on day one, up to about 20–30 ml by day three).¹ These amounts are exactly right for a newborn stomach, which is approximately the size of a marble on day one.

Colostrum transitions to mature milk around days 3–5 post-birth, often described as the milk "coming in." This transition can cause breast engorgement — fullness, firmness, and sometimes pain. Frequent feeding (8–12 times in 24 hours) is the most effective way to manage engorgement and establish a good supply.

Feeding frequency in the first weeks: aim for at least 8–12 feeds in 24 hours, including overnight. Newborns have small stomachs and breast milk digests quickly. Longer gaps in the early weeks can undermine supply and leave the baby hungry. Feed on cue — do not wait for crying.

Latch and positioning

A good latch is the foundation of comfortable, effective breastfeeding. A poor latch causes nipple pain, ineffective milk transfer, and supply problems — most of which resolve once the latch improves.

Signs of a good latch:

• Baby's mouth is wide open, taking in not just the nipple but a good portion of the areola
• The chin is touching the breast; the nose is clear or barely touching
• The baby's lips are flanged outward (not tucked in)
• You can hear swallowing — not clicking or smacking
• Feeding is not painful after the initial few seconds

Signs of a poor latch:

• Nipple pain throughout the feed or lasting after the feed ends
• A clicking or smacking sound
• Baby coming on and off repeatedly
• Nipples appear creased, flattened, or blanched after feeding

A baby who is latched shallowly (nipple only, not much areola) cannot draw milk effectively and compresses the nipple against teeth and hard palate — which causes pain and ineffective transfer. If latch is painful, remove the baby gently by inserting a clean finger into the corner of the mouth to break the seal, and try again.

Positioning options — cradle hold, cross-cradle, football hold, laid-back feeding, side-lying — are all viable. The best position is the one that allows a good latch, keeps your back comfortable, and works for both of you.

Knowing baby is getting enough

You cannot see how much milk a breastfed baby takes in. These indirect signs are the reliable check:

• 6+ wet nappies a day from day 5 onwards — the single most useful indicator²
• Regular weight gain after the initial post-birth dip (up to 7–10% weight loss in the first few days is normal; birth weight should be regained by 2 weeks)¹
• Regular stool output in the first 6 weeks — yellow, seedy, soft stools after most feeds
• Baby seems satisfied after feeds, has alert wakeful periods, and is not continuously distressed
• Breasts feel softer after a feed than before

Weight checks with a health visitor or midwife are the definitive measure. If you are concerned, ask to have your baby weighed — this is always an appropriate request.

Common worries

Low supply

True low supply is less common than parents fear, but supply concerns are one of the top reasons for stopping breastfeeding earlier than planned. Most cases of perceived low supply are actually about timing — a baby going through a growth spurt will feed more frequently for a few days to signal the body to produce more. This looks like low supply but is the system working correctly.

Genuine low supply can be caused by: insufficient feeding frequency in the early weeks, significant supplementation without pumping, certain medications or hormonal conditions, previous breast surgery, or (rarely) insufficient glandular tissue. If supply is a genuine concern, an IBCLC assessment is more useful than generic advice.

Oversupply and fast letdown

Some parents produce significantly more milk than their baby needs. This causes: uncomfortable fullness, frequent leaking, forceful letdown that causes the baby to choke or pull off, gassy baby, and green frothy stools (from excess foremilk). Block feeding — feeding from one breast for a set period before switching — can help regulate supply.

Engorgement

Engorgement occurs when breasts fill faster than they are emptied — commonly in the first days as milk comes in, or after any gap in feeding. Frequent feeding is the primary treatment. Cold compresses between feeds and warm compresses just before feeding can help with comfort. Cabbage leaves applied to the breast are a traditional remedy with some evidence of reducing discomfort.³

Blocked ducts and mastitis

A blocked duct feels like a hard, tender lump in the breast. Continued feeding from the affected side (uncomfortable as it is), gentle massage toward the nipple, and warmth before feeds usually resolve it within a day or two.

Mastitis — inflammation of the breast, often with redness, warmth, and flu-like symptoms — requires the same approach plus monitoring. Most mastitis resolves without antibiotics, but if symptoms worsen or do not improve within 24 hours, speak to a GP as a course of antibiotics may be needed.⁴ Do not stop feeding from the affected breast.

Pumping basics

Expressing milk by pump or hand allows someone else to give feeds, helps establish or maintain supply when a baby cannot feed directly (e.g., premature birth or latch difficulties), and builds a freezer stash for returning to work.

Electric pumps (particularly hospital-grade double pumps) are the most efficient option for regular expressing. Hand pumps work well for occasional use. Hand expression is a skill worth learning — it works without any equipment and is often more effective in the first few days when volumes are small.

If pumping to establish or protect supply alongside a baby who is not latching, aim to pump every 2–3 hours, including at least once overnight, in the early weeks. Frequency matters more than duration.

Breast milk storage

Fresh breast milk can be stored at room temperature (up to 25°C) for 4–6 hours, in the fridge (4°C or below) for up to 4 days, and in a freezer (−18°C or below) for up to 6 months.⁵

Store in clean sealed containers or breast milk storage bags. Label with the date expressed. Thaw frozen milk in the fridge overnight or under cool running water — do not microwave (creates hot spots, destroys some bioactive components). Use thawed milk within 24 hours. Do not refreeze.

Vitamin D supplementation

Breast milk does not contain enough vitamin D to meet an infant's needs regardless of the parent's own vitamin D levels.⁶ The NHS recommends all breastfed babies receive a daily supplement of 8.5–10 micrograms (340–400 IU) of vitamin D from birth until they are consuming 500 ml of formula per day (formula is fortified).⁶ The AAP recommendation for the US is 400 IU/day from shortly after birth.⁷

This is one of the few areas where breastfeeding requires active supplementation. Vitamin D drops for infants are available from pharmacies and supermarkets without prescription.

Combination feeding

Combination feeding — mixing breastfeeding and formula — is common and workable. The main consideration is the timing: introducing formula in the first 4–6 weeks before supply is established can reduce supply if the breast is not also stimulated at the same time. After supply is established, most parents can introduce a formula feed without supply impact.

Combination feeding is appropriate when: medical circumstances require supplementation, returning to work makes exclusive breastfeeding impractical, the breastfeeding parent needs shared feeding for rest, or the baby is not gaining weight adequately on breast milk alone. Any breastfeeding is better than none — partial breastfeeding still provides immunological benefits.

Cluster feeding

Cluster feeding — where a baby wants to feed repeatedly over several hours, usually in the evenings — is a normal breastfeeding pattern, not a sign of low supply. It is especially common in the first weeks and during growth spurts.

→ Deep dive: Cluster feeding

When to wean

The WHO recommends exclusive breastfeeding for 6 months, then continued breastfeeding alongside complementary foods for 2 years or beyond.[^8] The AAP recommends breastfeeding for at least 12 months.¹ The NHS recommends at least 6 months of exclusive breastfeeding, then continued alongside foods for as long as both parent and baby wish.²

There is no age at which breastfeeding becomes harmful or inappropriate. Weaning happens when the parent, the child, or both are ready. Gradual weaning — dropping one feed every few days — is easier on the body (reducing engorgement risk) than sudden stopping.

← Back to: Feeding your baby: the complete guide

Sources

1. American Academy of Pediatrics. "Breastfeeding and the Use of Human Milk." Pediatrics 150(1), 2022. https://publications.aap.org/pediatrics/article/150/1/e2022057988/188347/Breastfeeding-and-the-Use-of-Human-Milk
2. NHS. "Breastfeeding: is my baby getting enough milk?" NHS, 2024. https://www.nhs.uk/conditions/baby/breastfeeding-and-bottle-feeding/breastfeeding/is-my-baby-getting-enough-milk/
3. Snowden HM, Renfrew MJ, Woolridge MW. "Treatments for breast engorgement during lactation." Cochrane Database of Systematic Reviews, 2001. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000046/full
4. NHS. "Mastitis." NHS, 2024. https://www.nhs.uk/conditions/mastitis/
5. NHS. "Expressing and storing breast milk." NHS, 2024. https://www.nhs.uk/conditions/baby/breastfeeding-and-bottle-feeding/breastfeeding/expressing-and-storing-breast-milk/
6. NHS. "Vitamins for children." NHS, 2024. https://www.nhs.uk/conditions/baby/weaning-and-feeding/vitamins-for-children/
7. American Academy of Pediatrics. "Vitamin D Supplementation for Infants." HealthyChildren.org, 2023. https://www.healthychildren.org/English/healthy-living/nutrition/Pages/Vitamin-D-Supplementation.aspx
8. World Health Organization. "Breastfeeding." WHO, 2024. https://www.who.int/health-topics/breastfeeding