In August 1997 I had a pituitary adenoma removed that was disrupting my ability to become pregnant. I was also diagnosed as having hypothyroidism and am on levoxyl. I became pregnant in February 1998, but the baby died in utero at five months. Is there ever any connection between hypothyroidism and miscarriage? If so, what should I do in the future if I am lucky enough to get pregnant again? Also, during my pregnancy my doctor never tested my hormone levels; what should I have been tested for, and how often?

Mandy

One cause of low thyroid hormone level is low thyroid-stimulating hormone (TSH) levels. If this is the case, then thyroid replacement should solve the problem. However, another cause of hypothyroidism is anti-thyroid antibodies. If these are present, they may be associated with problems that could cause miscarriage.

Women with anti-thyroid antibodies often have antibodies to antiphospholipids (APL), which are important components in the blood-vessel walls of the placenta. If these antibodies are present, blood flow in the placenta can be cut off, resulting in pregnancy loss.

Midtrimester stillbirths are best followed up by checking the chromosomes of the fetus and completing an autopsy. If this was done, you may want to review the findings with your physician. If chromosomal analysis or autopsy were not performed, you may still be able to glean information regarding a possible immune mechanism for the pregnancy loss. You would need to send a microscopic specimen from the placenta -- which should have been preserved -- for pathological review by a trained placental pathology specialist, who will perform special staining of the slide to check for immune causes.

If an immune cause for pregnancy loss is identified, you may benefit from treatment with heparin and aspirin, white-cell immunization, high-dose progesterone or intravenous immune globulin. Immunotherapy is controversial, and while many studies offer promise, the experimental data has not shown conclusively whether any of these immunotherapies is effective. For more information on this topic, see my previous column on Imm unological Causes of Miscarriage.