I'll preface my response by saying I've torn (mild but did require stitches) in the same place with all three births, regardless of their size (2.9kg, 3.6kg and 4.5kg). However, I didn't feel it happen (in all 3 births) and didn't have any probs afterwards with pain/discomfort. Probably just lucky, I guess. I'd suggest perineal massage and then, during the final stages of labour/pushing, having a warm compress put on your perineum (by midwife). Probably my best advice though would be to do your best to listen to the midwives and try not to push when bub is crowning. Not necessarily the most comfortable of sensations as you probably recall, but it doesn't last long and gives your body a chance to adjust to the stretching.