I wish I could help Cindy. I never knew a goiter could have an unknown cause, I always thought it was related to a malfunction in the thyroid. My great aunt had her thyroid removed (she had hypothyroidism). Her goiter was so prominent it could be seen by other (her neck being so swollen that is). Yes, she had a difficult time breathing and even had sleep apnia (Here is some information I found on the net that may be helpful.
Hormone level could be high, low or normal
Goiter doesn't necessarily mean your thyroid gland isn't producing hormones normally. Even when enlarged, your thyroid may produce below-normal, normal or above-normal amounts of hormones.
Enlargement of the gland can be uniform (diffuse goiter), or the gland may be enlarged due to one or more nodules (nodular goiter). Nodules are lumps within an otherwise normal thyroid gland.
One cause of goiter is iodine deficiency. In this situation, your thyroid can't make and release enough thyroxine and T-3 — both of which contain iodine — and enlarges in response to excess stimulation from the pituitary.
Many causes of thyroid enlargement exist other than iodine deficiency. Some of the causes are serious, others not. Other causes of goiter include:
Graves' disease. This disease, an autoimmune disorder, is the most common cause of an overactive thyroid (hyperthyroidism). In Graves' disease, antibodies produced by your immune system stimulate the thyroid to produce too much thyroxine. Normally, your immune system uses antibodies to help protect against viruses, bacteria and other foreign substances that invade the body. In Graves' disease, antibodies mistakenly attack your thyroid gland and occasionally the tissue behind your eyes and the skin of your lower legs. Scientists aren't sure why Graves' disease occurs. The overstimulation of your thyroid in Graves' disease results in uniform and nonpainful swelling of the gland.
Hashimoto's disease. This disease, also called chronic lymphocytic thyroiditis, is a common cause of an underactive thyroid (hypothyroidism). Hashimoto's disease also is an autoimmune disorder and causes inflammation, which impairs your thyroid's ability to produce hormones. Then, your pituitary gland attempts to stimulate your thyroid gland to produce more thyroid hormones, causing your thyroid gland to enlarge.
Multinodular goiter. In this condition, several nodules develop in both sides of your thyroid, resulting in overall enlargement of the gland. Multinodular goiter may occur with normal, low or excessive thyroid hormone production.
Solitary thyroid nodules. A solitary nodule describes a single nodule that can occur in any part of your thyroid gland. Most nodules are noncancerous (benign) and don't lead to cancer.
Thyroid cancer. Thyroid cancer is less common than benign thyroid nodules. Cancer of the thyroid often appears as an enlargement on one side of the thyroid.
Pregnancy. A hormone produced during pregnancy, human chorionic gonadotropin (HCG), may cause slight uniform enlargement of your thyroid gland.
Inflammation. Thyroiditis is an inflammatory condition of the thyroid. Various types of thyroiditis can result in an enlargement of your thyroid gland. Some may cause thyroid pain, often aggravated by swallowing or pressure. Some types of thyroiditis are associated with hyperthyroidism.
http://www.cnn.com/HEALTH/library/DS/00217.html
Cindy,
Note that one of the causes is pregnancy. It may be that your goiter will go away once your not pregnant anymore. I would advise a second opinion, possibly from the OB/GYN or the CNM that is handling your pregnancy because I'm sure they've seen this type of situation before. I'm not a doctor but from what I'm reading on the net here and from what I know about my family history with my aunt, having the surgery isn't something you need to rush into so you most likely have time to explore all your options and get other opinions on this. Don't panic - you'll be fine.
:-3
:-3