Gum's the word

My husband recently had part of his bowel removed, and was given chewing gum to stimulate his remaining bowel. It did seem to help. So is chewing gum good for you? My parents would have been shocked at such a suggestion.

The act of chewing, without swallowing anything solid, after a bowel operation starts the saliva and other digestive juices flowing. The bowel wall muscles respond, too, with regular and coordinated contractions. It's a safe way to "kick-start" normal intestinal action. Studies show that the hexitols used to make gum sweet can cause gas and gut cramps, so you can overdo things if you're constantly chewing.

Why is my mouth dry?

I have a dry mouth, more so at night while sleeping. I wake up four to six times to drink water; I also mouth-wash before bed and use rehydrate tablets regularly. Is it an age thing (I'm 42), or do I need treatment?

A dry mouth of recent onset occurring at night can have several causes. You may simply be breathing through your mouth because your nose is blocked, which will dry out your mouth even if you are producing plenty of saliva. Do you know if you snore? If so, you may need an ENT examination. More likely is that you aren't producing enough saliva. This can have several causes, from stones blocking your salivary ducts to a condition called Sjögren's syndrome, in which many of the body's secretions are inadequate. Do you have dry eyes, too? This may indicate Sjögren's. It's not your age. Go to your doctor for a check-up - and your dentist, too, because it may be affecting the health of your gums.

Warm-up warning

My partner and I resolved to take more exercise this year, and have taken up seven-a-side football. It's great fun, but we're short of time and go straight into the game without warming up. Friends say this is dangerous and we could get injuries. Are they right?

Your friends may have read a recent report on Norwegian women's football - on 125 teams, no less, for such a small population. They compared the injuries sustained by nearly 1,900 women asked to follow a specific warm-up programme before playing with those in 837 women who did "their own thing". The warm-up improved the strength and muscle control, and cut relatively minor injuries by a third and serious injuries by half. So take that extra time to get to the club early and do 20 minutes of warm-up exercises before you start to play.

Pregnancy: a weighty issue

I'm halfway through my third pregnancy. I was about two stone overweight when I conceived, and have since put on another two stone. I just don't seem to be able to stop eating. My midwife and doctor are very concerned and want me to lose most of the extra weight before the birth. Do I really have to? And what are the risks if I don't?

You aren't going to like this, but please take my answer seriously. You have more than twice the risk of other women of becoming diabetic and of developing high blood pressure and pre-eclampsia in the last three months. What's more, your baby has a high chance of weighing more than 4kg (9lb), and there is a raised risk of stillbirth. And if you have an anaesthetic, you will have a raised chance of complications. So please, follow your midwife's advice.

• Do you have a question for Dr Smith? Email doctordoctor@theguardian.com