How poisonous or harmful a substance is depends on many different factors, including the amount you're exposed to, when in the pregnancy you were exposed, how you were exposed, your genetic makeup, and the degree of risk associated with a particular substance. While there is fairly good information about many drugs and infections that are potential teratogens, there is a sore need for more data on the reproductive and developmental risks of most chemicals. If you are exposed to any chemicals on a routine basis, you may want to talk about it with your healthcare provider. Since you can't be expected to live in a sterile bubble for the next nine months, you're smart to be thinking about how to protect your developing baby. You can be exposed to lead if your hobbies have anything to do with ceramics, jewelry making, print making, electronics, glassblowing, or stained glass.
Lead exposure is also common during home renovations when old paint is removed.
It's best to avoid these activities while you're pregnant. Generally, lead gets into water when it leaches from old pipes, so let the tap run for a few minutes before filling your glass or teakettle, or fill containers with drinking water from the tap after you've run water for washing dishes. Finally, avoid taking calcium that comes from dolomite or bone meal, which are often contaminated with lead. If you're concerned about lead, a simple blood test can detect the extent of your exposure and may save you from needless worry. It's best to eat these fish no more than once a month.