New mums have different breast milk concentrations which can impact babies growth up to age five

New mums have different concentrations of breast milk which can affect a baby’s growth rate up until their fifth birthday, new research has revealed.

Some complex sugar molecules, called human milk oligosaccharides (HMOs), found in breast milk could help babies who are behind the growth curve while others could do the opposite and help lower the risk of childhood obesity, the new study suggests.

Previous studies have found breastfeeding can impact infant growth and help prevent obesity, both in childhood and later in life.

But the components of breast milk responsible for such benefits remain mostly a mystery.

Human milk is an elaborate blend of proteins, fats, minerals and vitamins, plus HMOs.

Read more: What causes breast milk to be bright orange?

There are approximately 150 types of HMOs and, like thumb and tongue prints, their combination and concentration is unique to each new mother.

In the new study, published by The American Journal of Clinical Nutrition, US researchers confirmed a link between HMO concentrations and infants’ weight and body composition, as found in previous research.

Earlier pilot studies looked at a smaller, study group of approximately 30 infants who were exclusively breastfed and who displayed excessive weight gain over a six-month period.

The new study, however, examined a much larger cohort of 802 mothers and their children who were examined from birth until the age of five.

It revealed that high concentrations of one HMO called 2'-Fucosyllactose (2'FL) and low concentrations of another HMO known as Lacto-N-neotetraose (LNnT) were associated with growth in infancy and early childhood.

Breast milk from mothers of taller and heavier infants and children tended to have less diverse HMO composition, higher concentrations of 2’FL and lower concentrations of LNnT.

Breast milk from overweight and obese mothers also tended to have less diverse HMO composition, higher concentrations of 2’FL and lower concentrations of LNnT.

Depending upon concentrations of HMOs in mother's milk, but independent of the mother's pre-pregnancy body mass index (BMI) or duration of breastfeeding, infant height and weight can vary by half a standard deviation.

Standard deviation is a measure of how spread out numbers are.

Study senior author Professor Dr Lars Bode, of the University of California San Diego School of Medicine, said: “We were surprised by the magnitude of the association.

“The impact persisted long after actual exposure to HMOs during breastfeeding.”

Read more: Pregnancy and breastfeeding lowers risk of early menopause

What are HMOs?

HMOs are natural prebiotics that contribute to the shaping of the infant gut microbiome, which may affect health and risk of disease.

But they also act independently of the microbiome, protecting the infant from diseases such as infectious diarrhoea or necrotising enterocolitis - a serious condition that impacts the intestine of premature infants.

HMOs may also reduce the risk for diseases such as asthma, allergies and obesity later in life.

Though the study authors acknowledge that more research needs to be done they hope confirmation of the link between different concentrations of breast milk and a baby’s growth rate could help to identify potential treatments for early childhood growth problems and obesity.

Dr Bode said: “Our goal is to generate a deep mechanistic understanding of how HMOs in a mum’s milk can contribute to infant health and development.

“Although we are only at the very beginning, the generated knowledge provides fascinating new opportunities.

“Some HMOs could help infants who are behind the growth curve. Other HMOs could do the opposite and help lower the risk of childhood obesity.

“We could even imagine applying HMOs as novel therapeutics for adults who either need to gain weight or suffer from overweight and obesity.”

The authors noted that, although their study linked HMO composition with early childhood growth, it couldn’t prove that variations in HMO patterns cause differences in children’s growth.

The research follows news that breast milk is rich in a chemical that combats infant infections.

The benefits of breast milk have long been discussed, but last year, scientists at the National Jewish Health and the University of Iowa identified a compound in human breast milk that fights infections caused by harmful bacteria, while allowing beneficial bacteria to thrive.

The World Health Organisation recommends breastfeeding exclusively for the first six months, and continued breastfeeding along with appropriate complementary foods up to two years of age or beyond.

But in June last year 2018 the Royal College of Midwives (RCM) guidance published new guidance for mothers, claiming mums should not be shamed into breastfeeding and their choice to bottle feed must be respected.

Additional reporting SWNS