I used to guzzle loads of Lucozade during my pregnancy with my second child because I believed that it would give me a little pick me up , due to the fact that I was still having terrible morning sickness. (I had it for the full nine months, morning , noon and night !) When I told my midwife at an appointment around the eighth month mark , she nearly went off her head , telling me that the foetus absorbs your excess sugar in late pregnancy and this can cause you to have a really large birth weight baby which could cause complications - this was backed up by my health visitor. It didn't help though that I was also craving sugar puffs - which ordinarily I loathe.(I did eat very healthily apart from this !) I cut out both at that stage and my daughter was 9 lb 4 oz at birth. I dread to think what she may have been if I hadn't stopped.
I think it's like everything else - the key is moderation. A little of what you fancy won't hurt but too much can cause problems. Lucozade is packed with sugar and is often given to diabetics who need a quick sugar rush as it is so heavily loaded with sugar so as long as she is not consuming exorbitant amounts , it shouldn't be a problem. A healthy diet and plenty of juicy fruits will give her just as much energy. Oranges are excellent and a good source of vitamin C . Pregnancy is draining on the body and it's important that she gets as much rest as possible and plenty of help from others where possible. I wish her all the best x