In over 25 years in clinical practice, I’ve seen a LOT of pregnant women. In the course of our conversations about the process of growing, giving birth to and nourishing a baby, virtually every pregnant client has asked me one question:
“What formula should I give my baby if I’m unable to breastfeed?”
I must confess that the first time I heard it, the question took me by surprise. I grew up surrounded by women – my own mother, her sister, older cousins, and later, colleagues’ wives – who had breastfed their babies, and it seemed like the most natural thing in the world to me.
It was only once I began hearing women’s stories and diving deep into the science of human lactation that I realised that while breastfeeding is indeed natural, it still has to be learned, just as wolf cubs must learn how to hunt, even though they’re naturally carnivorous.
However, none of us will invest the time and effort required to learn something unless doing so offers us something that we value. Most women have a fairly amorphous sense that ‘breast is best’, but very few are aware just how valuable – in fact, irreplaceable – breastfeeding is, both for their babies and themselves.
And now I have an even better value proposition to put to my pregnant clients when we’re discussing breastfeeding: A systematic review and meta-analysis published in JAMA Network Open found convincing evidence that women who have breastfed have a reduced risk of developing diabetes and high blood pressure in the future, and a review article published in Pediatric Research found that breast milk helps set babies’ body clocks, encouraging better sleep patterns and enhancing physiological attunement with their mothers
First, let’s unpack the connection between breastfeeding, diabetes and high blood pressure. The JAMA article, a meta-analysis of 6 studies including more than 200 000 participants, found that women who breastfed for more than 12 months in total had a 30% lower risk of becoming diabetic, and a 13% lower risk of developing high blood pressure, than mothers who breastfeed for less than 12 months, after making statistical adjustments to take into account cardiovascular risk factors including obesity, smoking, and family history.
The researchers also conducted a systematic review of studies on breastfeeding and cardiometabolic disease, and found that:
- Every year of breastfeeding (including total breastfeeding duration and duration per child) was associated with a 14% reduction in the risk of development of diabetes.
- Breastfeeding was associated with reduced atherosclerotic plaque, as determined by measuring carotid intima-media thickness, and the longer the duration of breastfeeding, the less plaque build-up.
- 3 years after giving birth, women who breastfed for more than 6 months had lower weight retention (i.e. they had lost more of their ‘baby weight’).
- Women who exclusively breastfed for 1 to 3 months had a lower risk of developing diabetes than those who ‘comped’ with formula.
- Even women who had developed gestational diabetes (diabetes that develops in pregnancy, disappears as soon as women give birth, but leaves both them and their offspring at a higher risk of developing diabetes) were protected against developing type 2 diabetes by breastfeeding.
- Exclusive breastfeeding for longer than 6 months or total breastfeeding for longer than 12 months was associated with a lower risk of developing hypertension later in life compared with no breastfeeding or breastfeeding for less than 6 months.
- The more children women breastfed, and the longer they breastfed them for, the lower the risk of developing hypertension in later life.
Why might breastfeeding be so beneficial to women’s cardiometabolic health? As the authors of the JAMA article point out, pregnant women experience changes in their lipid (cholesterol and triglyceride) profile, insulin resistance and glucose intolerance, and weight gain that are necessary to support the foetus’ growth and development, but are adverse to their own health.
Breastfeeding reverses all these adverse changes: it expends 500 calories per day and mobilises the mother’s fat stores to help her lose her ‘baby weight’ and recover her insulin sensitivity, draws down on her cholesterol in order to pack it into the milk her body produces, and triggers the release of oxytocin which lowers perceived stress and blood pressure.
In the authors’ words,
“Breastfeeding is a reset mechanism to the adverse metabolic profile in pregnancy, so women who do not breastfeed may be at risk for a persistently dysmetabolic state.”
Or to put it plainly, pregnancy messes with women’s bodies, and breastfeeding helps to sort out the mess!
But even women who are sold on the health benefits of breastfeeding may give up on it if they don’t receive effective help in solving some of the challenges that almost invariably surface, particularly in the early days.
One of those problems is the round-the-clock nature of breastfeeding, especially in the first few weeks and even months of a newborn’s life.
Many fear that they are ‘not making enough milk’ because their babies cluster-feed all afternoon and evening, and then wake multiple times during the night to feed again.
Instead of being educated about the finely-tuned supply-and-demand economy of breastfeeding – the more milk a baby takes, the more the breast produces – they may be persuaded to ‘comp’ their babies with formula at night, with the promise that the extra calories and the slow-to-digest nature of formula will help their baby sleep through the night.
However, the law of supply and demand is unbreakable: the practice of comping diminishes the baby’s demand for milk, which in turn leads to to dwindling breast milk supply, increased formula feeding, and more often than not, early termination of breastfeeding.
The great irony is that breast milk is engineered by Mother Nature to help set the newborn’s body clock, which is a crucial element in developing an appropriate sleep-wake cycle, as the second study I’m profiling in this post illuminates.
Titled ‘Human milk as “chrononutrition”: implications for child health and development’, the article summarises research that indicates that breast milk is “a powerful form of ‘chrononutrition,’ formulated by evolutionary processes to communicate time-of-day information to infants.”
Here are a few fascinating snippets:
- Breast milk produced during the day contains 330% more cortisol (which promotes alertness, feeding behavior, and catabolic processes) and more activity-promoting amino acids than milk made at night
- Night milk contains high levels of melatonin and tryptophan to foster sleep, relax digestion, and support anabolic activities including growth and cell restoration.
- Night milk has more fat than day milk, which promotes greater satiety.
- There are higher levels of 5′AMP and 5’GMP, which are compounds that help trigger the release of GABA (the brain’s natural ‘valium’) and melatonin (the sleep hormone),
- Levels of leptin, which reduces appetite, are significantly higher in milk made between 10 p.m. and 4 a.m. than milk made between 4 a.m. and 10 p.m.
- Milk made during the day – when babies are more likely to be exposed to sources of infection such as older siblings, visitors and outings to public places – has higher levels of key immune factors including immunoglobulin A, C3 and C4 proteins of the complement system, and polymorphonuclear phagocytes (immune cells that ‘gobble up’ intruders) than night milk.
Why might be the purpose of breast milk conveying these circadian signals? Quite simply, every important physiological function in our bodies – sleep–wake cycles, respiratory rate, body temperature, digestion, metabolism, hormone release, growth, detoxification, tissue repair – is controlled by circadian clocks.
It is well known that dysregulated circadian rhythms are linked with poor immune function, sleep problems, psychological disorders and other physical and mental health problems in adults.
However, as every parent of a newborn knows, babies are born without a fully operational circadian clock. It may take as long as 9 months for them to develop their own internal time-keeping mechanisms, signalled by emergence of a daily circadian patterns in the key time-keeping hormone cortisol.
Hence, the daily, predictable fluctuations in hormones, nutrients and immune factors that they receive from breast milk – all of which easily cross the gut barrier and diffuse into their blood and tissues – may be crucial in entraining their circadian rhythm before they’re able to carry out this critical function on their own.
And in support of this hypothesis, breastfed infants have higher sleep efficiency and less fragmented sleep in early life compared to formula-fed infants.
The review article raises an important point: women who express their breast milk either for their own baby’s consumption, or for donation to a milk bank, should note the time of day that the milk was made to avoid mis-timed circadian signals that could potentially disrupt the baby’s body clock.
So now I have two more items to add to my already lengthy list of reasons why women should arm themselves with all the resources they need to maximise their chances of succeeding at breastfeeding.
I find that when women are given the opportunity to express and address their fears about breastfeeding, and then engaged in a discussion that deepens their respect for the miraculous process by which their bodies make nourishment that is so precisely matched to their infant’s ever-changing needs – both physical and psychological, they are far more motivated to appropriately prepare for it.
I encourage all pregnant women to join the Australian Breastfeeding Association and to start attending ABA meetings and meet their local group leader well before they give birth, so they can learn the womanly art of breastfeeding from experienced mothers, and be armed with resources to help them trouble-shoot if they hit any bumps in the breastfeeding process.
With appropriate support and guidance, the vast majority of women can breastfeed their babies exclusively for around the first 6 months and continue to breastfeed once solid foods are introduced, for at least 1 year and preferably beyond, as recommended by the World Health Organization, American Academy of Pediatrics and other heath care organisations.
Finally, my answer to the question “What formula should I feed my baby if I can’t breastfeed?” is that for those women who cannot breastfeed their babies, human breast milk from screened donors is the next best option, and infant formula is the last resort. No infant formula has been found to deliver better growth and development outcomes than any other, so the choice of formula comes down to the parents’ ethical stance, and the tolerability of the formula to the infant.
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