According to a review of previous research, by Toronto's Mount Sinai Hospital, it apprears that the best baby painkiller, is breastfeeding

The research compared babies who were swaddled, cuddled, or given a placebo, and it found that the babies who were breastfed experienced the least pain, and it's thought that the mother's presence was the key.

The research illustrates that permature babies who had to undergo many painful procedures during the first weeks of their life could be helped by breastfeeding. At best it was the most inexpensive and effective way to relieve baby's pain.

The researchers thought that it could be linked to the sweetness of breast milk, and a concentrated sugar solution has been found to soothe them just as well

Baby's pain was measured by their breathing, heartrate and the length of time the baby cried after the injection.