A Question of Health

WHY DO contraceptive pills come in packets of 21?

The men who invented the contraceptive pill decided women liked seeing a period every month. So they produced a system that induces a bleed every 28 days. Bleeding that occurs when you take the pill is artificially induced by hormones - it is not a true menstrual bleed. The pill could easily have come in packets of 35, which would produce a period every six weeks, or 65, which would cause bleeding every nine weeks.

Some women take three packets consecutively, followed by a one-week break, and this means they get only four periods a year. This system of "tri- cycling" is effective and causes no harm.

MY MOTHER had an underactive thyroid gland and I think I may be developing the same thing. What symptoms should I look out for?

Weight gain, constipation, dry skin, hair loss, feeling cold, puffiness around the eyes, depression, general tiredness and slowing down. But if the thyroid gland is not producing sufficient hormones, it usually begins slowly and insidiously, with vague symptoms of tiredness. Women are affected by hypothyroidism much more than men, and thyroid problems, both underactive and overactive, often run in families. Sadly, most people who are overweight, myself included, do not have underactive thyroid glands.

MY FOUR-month-old son has had a sticky eye since he was born. Can anything be done about it?

Your son has a blocked tear duct, the tiny channel that drains tears away from the eye. It's quite a common problem. The good news is that the duct almost always opens up without any intervention from doctors. Just keep the eye clean with cotton wool and clean water.

HOW MUCH effect does diet have on cholesterol levels?

Most people can reduce raised cholesterol levels by up to 10 per cent by cutting down on their intake of fat.Drugs known as statins can reduce cholesterol levels more effectively than dietary changes, with hardly any side-effects. Although cholesterol causes heart disease, it has to be seen as part of a wider picture, including smoking, exercise, blood pressure, obesity and genetic factors.

Please send questions to A Question of Health, The Independent, 1 Canada Square, Canary Wharf, London E14 5DL; fax 0171-293 2182; or e-mail to health@independent.co.uk