First-time parents are often unprepared for the frequency with which their breastfed newborns need to feed, or how long night-time breastfeeding is likely to continue.
Breastfed babies are generally still feeding as frequently throughout the night at 3 months of age as they were at 1 month (Elias et al 1986; Ball 2003).It has been suggested by various researchers that frequent night waking is a factor contributing to the introduction of formula milk to babies, thereby undermining breastfeeding (Pinilla & Birch 1993; Marchand & Morrow 1994; Greenslade 1995; Ball 2003) given the common (but possibly no longer valid - see Doan et al 2007) perception that formula use promotes infant sleep.
For those committed to breastfeeding, sleeping with their babies becomes one of the means by which mothers cope with frequent night-time feeding and later settling.
A study of 253 families in the North-East of England reported that mothers who started bed-sharing in their babies' first month of life were twice as likely to still be breastfeeding when their baby was 4 months of age, in comparison with women who breastfed their baby in the absence of early bed-sharing (Ball 2003). Similar results have been seen in other studies (Blair and Ball 2004; Clements et al 1997; Elias et al 1986; Ford et al 1994; McCoy et al 2004; Mitchell & Scragg 1994; Rigda et al 2000; Quillin and Glen 2004; Baddock et al 2007, Santos et al 2009) indicating that bed-sharing is an important night-time care strategy in the context of breastfeeding. Results from the NECOT trial showed that participants who had reported bed-sharing in the first 13 weeks postnatally were half as likely as those who had reported no bed-sharing to have ceased breastfeeding at any given point (Ball et al 2011). A recent study using data from US mothers (Huang et al 2013) showed that, after adjusting for covariates, longer bed-sharing duration was associated with longer duration of any (but not exclusive) breastfeeding.
Although it is not possible to say that bed-sharing causes women to continue breastfeeding it seems likely that a positive feedback loop exists, and the two behaviours are mutually reinforcing: bed-sharing facilitates frequent feeding which supports milk supply, while breastfeeding introduces oxytocin into the mother's blood and milk, reducing mothers' blood pressure (Jonas et al 2008) and inducing sleep for both mother and infant (Stuart-Macadam & Dettwyler 1995; Hrdy 1999). Bed-sharing breastfeeding mothers cope more easily with frequent night time feeds, getting more sleep and continuing to breastfeed for longer. McKenna and Gettler (2014) have termed the combination of bed-sharing and night-time feeding 'Breast-sleeping'.
Bed-sharing inherently puts mothers and babies in close body contact; a condition which anthropologists and others consider to be the evolutionary 'norm' for human infants - click here for more information. Bed-sharing has a number of benefits, as identified by researchers, or as perceived by parents who choose to bed-share. The flip-side of these factors can be viewed as the risks or drawbacks associated with cot sleeping.
However bed-sharing is not a risk-free activity, and no studies have found that the parents' bed is safer than a cot beside the parents' bed.
It is important that parents are made aware of how their individual circumstances affect risk; the magnitude of their personal risk-related behaviours, and how these may change from night-to-night . Parents should also know about the risks and consequences of alternate infant sleep locations, some of which can be more hazardous than bed-sharing, and are given the tools to arrive at an informed decision about whether or not to bed-share with their infant at any given time.