Discussion
Summary of main results
The results of this review demonstrated a statistically significant positive effect of skin-to-skin contact (SSC) on the following primary outcomes: breastfeeding one month to four months postbirth, SCRIP score first six hours postbirth, and blood glucose mg/dL at 75 to 90 minutes postbirth, We did not identify significant between group differences in duration of breastfeeding, and results relating to infant axillary temperature at 90 minutes to two hours postbirth were difficult to interpret due to high heterogeneity.
We found a statistically significant and positive effect of SSC on the following secondary outcomes: success of the first breastfeeding (IBFAT score), mean variation in maternal breast temperature 30 to 120 minutes postbirth, infant did not exceed physiological parameters for stability, number of babies not crying for more than one minute during a 90-minute observation, amount of crying in minutes during a 75-minute observation period and PCERA dyadic mutuality and reciprocity 12 months postbirth. We did not identify significant between group differences in successful first breastfeeding (IBFAT score 10 to 12 or BAT score 8 to 12), infant heart rate 75 minutes to two hours postbirth, infant respiratory rate 75 minutes to two hours postbirth, infant body weight change (grams) day 14 postbirth, transfers to the neonatal intensive care unit, infant hospital length of stay in hours, or PCERA maternal positive affective involvement and responsiveness 12 months postbirth.
No negative outcomes associated with SSC were reported in any of the studies except Sosa 1976a, who reported a longer duration of breastfeeding in the control group.
In summation, the totality of significant outcomes relating to breastfeeding, infant physiology and maternal neurobehavior supports the use of SSC in the early period after birth. However, this overall finding should be treated with some caution: for many outcomes only one or two studies contributed data, and for those outcomes where several studies were combined in meta-analysis there was considerable heterogeneity between individual studies. At the same time, some of those results that did not reach statistical significance were derived from small studies which did not have the statistical power to demonstrate differences between groups.
Breastfeeding/lactation outcomes
Only two breastfeeding meta-analyses contained more that three studies. Thirteen studies (702 infants) reported breastfeeding rates between one and four months postbirth (Analysis 1.1) demonstrating that mothers in the SSC group were more likely to be breastfeeding than those in the control group. The only other outcome with more than three studies (seven studies, 324 infants) was breastfeeding duration (Analysis 1.2). Infants in the SSC group breastfed an average of 42.55 days longer than control infants and when a study with inconsistent results was removed from the analysis the difference between groups was statistically significant. Evidence for breastfeeding exclusivity was conflicting, being no different at hospital discharge (Analysis 1.7, 2 studies) but significantly greater at three to six months postbirth (Analysis 1.9, three studies).The findings of improved breastfeeding for the two largest meta-analyses in this review were obtained in diverse countries and among women of low and high socio-economic class.
Results for IBFAT scores for the first breastfeeding postbirth were conflicting with one meta-analysis which treated this outcome as a dichotomous variable (Analysis 1.12) demonstrating no significant between group differences and another meta-analysis which used interval level data (Analysis 1.11) finding a significant effect of early SSC. Moore 2005 also found that SSC and the mother's nipple protractility contributed equally to the variance in infant IBFAT scores.The mother's nipple protractility was important in relation to the infant's ability to establish competent suckling. Dewey 2003 reported that suboptimal breastfeeding behavior during the first 24 hours postbirth was associated with the mother's flat or inverted nipples (RR 1.56). These infants were also 2.6 times more likely to have excessive weight loss.
Timing of when this outcome is measured may be critical because most healthy full term infants spontaneously grasp the nipple and begin to suckle by approximately 55 minutes postbirth. During the first 30 minutes, they may only lick the nipple. Widstrom 2011 found that some infants may take up to 45 minutes to latch after crawling towards and reaching the nipple and recommended that this process should not be disturbed or forced. Also, the intervention will be more successful if a clinician reassures the mother that healthy full term babies are able to crawl to the breast and begin to nurse on their own without assistance when they are ready. After the first two hours postbirth, infants often become sleepy and difficult to arous