How often have you been told "Just give your breastfed baby a bottle of formula at bedtime to make him sleep"?
Although this advice is almost some kind of folklore among the believers, there are some health professionals who may even advise you to do this with a newborn. Some will tell you that giving a bottle is a great way for fathers to "get involved".
But does this really work? And what could be the trade-offs? Here's what you need to know.
Your milk supply
Your breasts work on a basis of supply and demand. This means that whatever milk you remove from your breasts, they will be signalled to make more milk – so if you start offering bottles of formula at any stage of breastfeeding, your breasts won't receive the signal to make milk.
Research by Dr Peter Hartman, from the University of Western Australia, affirms that an 'empty' breast (and no, your breast is never actually empty) makes milk quicker than a fuller breast. So by offering a bottle of formula, unless you also express at this time, you could be compromising your milk supply.
Your newborn's tummy is only the size of his tiny fist, so it's normal for your baby to need frequent feeds in the early weeks. This is a time when your own milk supply is being established, and in these early times, you'll be developing more prolactin (the milk-making hormone) receptors in your breasts – so if you feed less because your baby is zonked out on formula, your body will not only get the message to make less milk, but you could be inhibiting breast development and influencing your ongoing milk supply.
On the other hand, if you feed according to your baby's cues in these early weeks, you'll encourage more breast development and set your milk production at a higher point. This will mean that as your baby's tiny tummy grows and he can manage a bigger volume of milk, you'll be producing a good amount, so he'll naturally start spacing out feeds and sleeping longer.
There's a very different tongue, jaw and sucking action required to drink from either a breast or a bottle. When your baby latches onto the breast, he needs to open his mouth wide, flange his lips and draw the nipple deeply into his mouth, while his tongue has to 'milk' the breast with rhythmic movements. When bottle-feeding, a baby doesn't have to open his mouth so wide or flange his lips to form a seal, nor does he have to work to get the milk out – he can simply latch onto the tip of the teat. If the bottle milk flows too quickly, the baby may thrust his tongue upwards to stop the flow.
This means that if you offer unnecessary bottles to your baby in the first 4 to 6 weeks, your baby may become confused by the different sucking actions. As a result, he may breastfeed less effectively, or he may prefer the faster flow of the bottle and refuse the breast.
If you do need to supplement in the early days, ask if you can try a small cup or a syringe. If you ever need to supplement and you use a bottle, finish a feed at the breast, after the bottle, so your baby associates a full tummy with breastfeeding. This can help avoid your baby preferring the bottle and refusing the breast altogether.
Exposure to potential allergens
Your baby is protected from potential allergens through your breast milk. He's also protected against viruses and bugs through the immune factors in your milk, so by introducing formula to try and get more sleep, the trade-off could be an unwell baby who is actually more wakeful if he becomes constipated or has an allergic response to the foreign proteins in formula.
Some parents find it helpful to offer a 'dream feed' – an extra feed just before they go to bed, no matter what time their baby last fed, so their baby's longer sleep may coincide with their own. But there are no guarantees that this will help all babies sleep longer – some babies will happily gulp an extra feed but seem to think, "Bonus! And I'll still wake up in a couple of hours for more!", while others will refuse to drink at all.
If you do want to try this as a way of getting more sleep, it's best to make this feed either a breastfeed top-up or a bottle of expressed breast milk so you'll be maintaining your milk supply.
Night milk and brain development
Remember this: your day and night milk have different components. Evening breast milk is rich in tryptophan, a sleep-inducing amino acid that's a precursor to serotonin. In turn, serotonin is a vital hormone for brain function and development that makes the brain work better, keeps one in a good mood and helps with sleep cycles.
We now know that ingestion of tryptophan in infancy leads to more serotonin development, creating the potential for life-long well-being. Night time breast milk also has amino acids that promote serotonin synthesis, so evening and night time breastfeeds could be more important to your baby's development than simply promoting sound sleep.
Getting more sleep: will formula really help?
If you're sleep deprived and wondering if a bottle of formula will get you more sleep, the answer is probably no. A 2015 study of babies aged 6 to 12 months, published in the Academy of Breastfeeding Medicine, found that night wakings or night feeds didn't differ between mothers who breastfed or formula fed. Another study showed that infants who were breastfed in the evening and/or at night slept an average of 40-45 minutes more than parents of infants given formula.
The researchers added that parents who supplement their infant feeding with formula in the hopes they will get more sleep should be encouraged to continue breastfeeding, because sleep loss of more than 30 minutes each night can begin to affect daytime functioning, particularly in parents who return to work.
Parents and partners
Of course it's your choice how you work out ways to get enough rest, as well as ways for partners to parent (they aren't just "getting involved" – they're parenting too!). There are plenty of ways for partners to connect with your baby other than giving a bottle: try bathing your baby, wearing your baby, or giving your baby a massage (check out my baby massage DVD – it's also available as a streaming download).
And partners, if you want her to express so you can give your baby a bottle, please note: you should wash the breast pump and tubing. It's an extra chore to express, without also doing a load of washing up – one of the best things about breastfeeding is that you can just whip out a boob and snuggle your baby, with nothing to clean up.
Pinky McKay is an internationally certified Lactation Consultant and best-selling babycare author. Her new revised version of Sleeping Like a Baby has just been released in print and audio. See it on Pinky's website at www.pinkymckay.com