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Reproductive Toxicant

Reproductive toxicants are substances that adversely affect fertility or a developing embryo or fetus. Toxicants, strictly speaking, are poisons. However, reproductive toxicants loosely include any infectious, physical, chemical, or environmental agent that has a damaging effect on fertility or embryonic development. Some substances that have a beneficial effect on one occasion (such as a dental x ray or aspirin) could be detrimental reproductively. The best defense against these toxicants is knowing what to avoid when.

Roughly 10-15% of couples trying to have a baby experience infertility. Infertility in men is usually due to low or abnormal sperm production or blockage in the male reproductive tract. Excessive alcohol, illegal drugs (like cocaine), radiation treatment, or infectious gonorrhea can all lead to sperm population problems. Female infertility is usually due to hormonal imbalance or pelvic inflammatory disease (PID). PID can be caused by sexually transmitted diseases (including gonorrhea) and can scar fallopian tubes, blocking egg travel and implantation. In addition, women whose mothers received the synthetic hormone diethylstilbestrol (DES) during pregnancy have higher infertility rates.

Infertility has additional causes. Copper or hormone deficiencies can cause infertility. Excessive iodine intake can cause infertility. And the cancer treatments radiation and chemotherapy can both be reproductively toxic. Cancer patients can freeze-store their sperm, eggs, or both for later implantation.

Toxicants that reach the developing baby by maternal exposure are called teratogens. Known teratogens include: excessive alcohol, tobacco smoke, certain medications, cocaine, x rays, some infectious agents, mercury, and lead. Most pose less threat to a mature adult than they do to a developing baby.

Alcohol is a devastating toxicant. Not only can alcohol increase abnormal sperm production in men, but it can also cause fetal alcohol syndrome (FAS) in developing infants. FAS is characterized by mental impairment, malformed facial features, poor coordination, heart defects, and other problems. Pregnant women who drink risk FAS in their unborn children.

Women who smoke during pregnancy have more miscarriages, still-births, and low birth-weight babies than non-smokers. And they have twice as many cases of cervical cancer as non-smokers. Cervical cancer can complicate conception or lead to infertility. Some evidence indicates that pregnant women who smoke also have more children with poor mental concentration.

Some drugs are teratogens. Aspirin and ergotamine (headache treatments) can cause abnormalities and miscarriages, respectively. The antibiotic tetracycline disfigures developing teeth. And certain diuretics, particularly Lasix, decrease levels of potassium (an essential electrolyte) in the fetus. Thalidomide, a sleeping drug never FDA-approved, causes limb deformities. Prescribers should always know if their patient is pregnant.

Other hazards pregnant women should avoid are x rays and certain infectious agents. Dental x rays in the first 12 weeks of pregnancy can double the risk of childhood cancers. And pregnant women should guard against contracting toxoplasmosis, rubella, and chicken pox. Toxoplasmosis is caused by a parasite in cat fur or feces which can cause infant blindness or death. Pregnant women should have someone else handle their cats. Rubella and chicken pox, if contracted during pregnancy, can also cause birth defects.

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