Extracted from Babycare Before Birth by Zita West (DK) £12.99

Until recently, scientists paid little attention to the effects of environmental agents on human reproduction, but a lot of research has been done on animals, revealing that chemicals do impact in particular on male reproduction, affecting the testes or damaging the sperm themselves.

Potential hazards
Genetic abnormalities in an embryo are a major cause of early miscarriage: they prevent normal development and the embryo dies. While this was previously thought to be a fault with the woman's egg, or random mutation, it is becoming evident that chromosomal abnormalities in sperm may be a contributing factor.

Although genetic abnormalities may be inherited, they can also be caused by environmental pollutants and lifestyle factors such as smoking. Sperm are particularly vulnerable to this because they are in constant production.

Once you are pregnant, your environment can have a profound effect on a developing embryo.

From day 15 to day 60 - that is, the second to the eighth week, known as the embryonic period - is a critical time for the development of your baby's organs. The impact of environmental factors during this time can affect the outcome. Don't start panicking, but be aware when you have a baby on board that certain substances pass through the placenta. There are more than four million chemical mixtures in homes and businesses that may affect a fetus, as well as environmental pollutants in air and water.

Around the house
Many products are potentially hazardous. Be especially wary of household cleansers, paints, varnishes, air fresheners, carpet cleaners, drycleaning fluids, printing inks, equipment or furnishings containing flame retardants and stain removers. You should also be conscious of beauty products such as hair dyes, nail polish and varnish, fragrances and deodorants. Many of these contain organic solvents - that is chemicals that dissolve other substances. Phythalates and parabens are chemicals which are used in some make-up products and toiletries, yet both are suspected of being hormone-disruptors, so get into the habit of checking labels carefully.

If you're a gardener, do not use powerful weedkillers or any other chemicals on the garden, and if you have hobbies such as painting and enamelling, use products with caution. To put it simply, if you are doing anything around the house that involves powerful chemicals, limit your exposure, ventilate the room well and wear protective clothes.

Metals to avoid
Lead is found in decreasing amounts in industry or manufacturing, but may still be found in piping in old houses. Arts and crafts material may have lead in them, and even some shampoos. Recent research shows that lead in sperm prevents it from binding to the egg. Lead has also been linked to stillbirths, deposits having been found in the placenta.

Vitamin C may assist in the removal of lead from the body, along with pectin, which is found in apples, pears and banans.

You are often exposed to mercury by eating contaminated fish. While trace amounts are present in most fish, it is most concentrated in large species. This is unfortunate because fish is such an important food, but I now recommend supplements instead. And avoid having mercury dental fillings put in or removed while trying to conceive.

Other metals to be wary of are cadmium (cigarettes, fertilizers, processed foods), aluminium (saucepans, foil, food additives) and copper (water pipes, jewellery, IUDs).

Pesticides
Avoid pesticides as much as possible (and beware anti-nit preparations!). Research has shown that exposure may contribute to miscarriage, premature birth and birth defects. (A study published in The Lancet in 1994 found that organic farmers had much higher sperm counts than farmers using chemicals.)

Some pesticides, known as endocrine disruptors, have oestrogen-like qualities that may affect the reproductive system of a fetus. Wash all fruit and vegetables, wear rubber gloves when gardening and avoid insect repellents containing DEET.

Other chemicals
Polychlorinated biphenyls (PCBs) are mixtures of chemicals that are no longer used in manufacturing of electrical equipment but can still be released into the environment from hazardous waste sites or leaks. They do not break down readily. PCBs have been linked to reproductive problems and impaired development in the womb as well as cancer.

Dangerous rays
Much debate continues about the effects of electromagnetic rays on our health. Should you limit your use of a mobile phone? Is autism linked to exposure to electromagnetic radiation?

• There has been a lot of concern in the past about radiation from computer screens causing miscarriage or even birth defects. But extensive research has so far shown this not to be the case. However, it's probably a good idea not to sit for hours with a laptop on your knee - and this applies to men as well as women. The jury is still out on mobile phones, and much more research is needed on long-term safety. So, carry your phone in a bag rather than putting it in your pocket, and keep it away from your abdomen.
• In the home, limit your use of the microwave and certainly don't stand in front of it while it's operating. You might also want to give your electric blanket a miss while you're trying to conceive. Keep each other warm instead.

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