You will probably find shes finding the sound and feel reassurring because this is what she became used to inside the womb. I agree with loza, you do need to be careful otherwise you may find in a years time, this is still the only way you can get her to sleep. You could also try gently patting her back or stroking the nape of her neck to settle her once shes lying down. When my daughter wasnt settling, I would lay her in her pram and rock her, then go lay her in her moses basket when she was asleep. I was very lucky though because at 2 months old, when it came to night time, I was able to lay her down in her basket upstairs while she was still awake, leave her, and she would drift off to sleep in her own time :)