My wife and I have been trying for a baby for about six months - my wife is urging me to give up my daily cycling because she says it could be lowering my sperm count. I don't want to, but I will if there's any truth in her claim - is there?

If it is a racing cycle with a racing saddle - the one that feels like a knife cutting into you - and you cycle a lot competitively, then there may be problems. Most reports, however, refer to impotence - because the saddle's pressure on the perineum damages the nerves that lead to erection - rather than to low sperm count. Tour de France cyclists, for example, tend to have trouble with sexual performance. If your bike has a normal saddle, and you cycle simply for pleasure, then it's not likely to do any harm. But why not try another sport (not horse riding, of course!) for a few weeks, to see if it makes a difference? Do it for your wife's sake, then you can both be relaxed about conception.

Is it true that there is a link between smoking and developing diabetes?

Yes, it is. Smoking is the health-destroying habit above all others. The follow-up of 17,000 babies born in Britain from March 3-9 1958 proved as long ago as 2002 that if you smoke during pregnancy, you increase your child's risk of developing diabetes. And if you smoke during your teenage years, your risk of becoming diabetic rises. The news gets worse: if you continue to smoke after you develop diabetes, you steeply increase your risk of heart attack, stroke, kidney disease and losing a limb due to gangrene. Enough said.