Many women worry about being distracted from their labour (that will usually demand their full attention). Setting up your labour support can minimise any interruption to your focus, and emotional well being. In prelabour (and early labour) you will need to create the space to be just a 'labouring woman'. You may need to have the child occupied, taken into another room (or taken for a walk), until the stronger, established labour sets in. If this is not possible, the labour may take a while to get established (hence the reason why many women start labouring strongly once their child is asleep at night).
Once you are in established labour, it is not usually so much of an issue. For many women their focus goes inward, and the events around them become less important. If you have any issues about having your child present, (possibly holding you back during the labour and the birth) then you may need to reconsider their presence, or organise for your child's support person to take them out at appropriate times. You may need to consider how your child will react to being removed, if you think it may be needed.
Some women labour better with their children around, because they know where they are, and how they are. They are able to get on with the job, ignoring any activity happening around them. They are used to the behaviour of their children (even if their carers aren't!) This is OK and should be accommodated.
Vocalising in strong labour is an important part of 'letting go' to birth for most women. If you are concerned about 'holding back' for the child, then again, arrangements may need to be made. Play-acting with your child before the birth, mimicking the loud sounds you can make, talking about how much hard work is involved in having a baby, are all good ways to prepare your child. Taking the situation 'back to them' (if they are old enough to understand) such as, "This is the noise I had to make to have you", often makes them think it is OK.