Hi Lisa,

I'm a mom of two, and certainly understand how strong those maternal urges are.

I did a little quick searching, and found only generic warnings about fentanyl (Duragesic) risk during pregnancy. Sounds like the usual warnings for other narcotic pain relievers. Here's what WebMD said:

"Fentanyl should be used during pregnancy only if the benefits to the mother outweigh the risks to the fetus. Talk with your doctor before using fentanyl if you are or may be pregnant. This drug can pass through your body in breast milk and should not be used while you are breast-feeding."

Reading between the lines, this probably means that there probably hasn't been many incidents of problems due to fetal exposure, but that they probably don't have enough data to rule it out, either. My guess is that the animal toxicology studies during initial drug testing probably didn't show a lot of teratogenicity (i.e. causing mutations to fetuses) either. Usually the pregnancy risk description for drugs that cause significant problems to animal fetuses at relatively low doses (i.e. the doses humans would use) are very strongly worded.

I remember reading that many anticonvulsants DO have a history of causing significant problems with human fetuses when taken by pregnant moms. I don't have that data on hand (although I know that Tegretol is one that is potentially a problem).

I did a quick search at PubMed, and couldn't find any papers about the worsening or improving of existing RSD during pregnancy. However, I did find a reference to one review paper that summarized data about RSD diagnosed during pregnancy. Here's the reference and abstract:

Eur J Obstet Gynecol Reprod Biol. 1999 Sep;86(1):55-63.
Reflex sympathetic dystrophy in pregnancy: nine cases and a review of the literature.

"OBJECTIVE: To better understand the diagnosis of reflex sympathetic dystrophy of the lower extremities in pregnant women. SUBJECT: Disease analysis using a retrospective series of nine cases and a review of the literature (57 patients and 159 sites of reflex sympathetic dystrophy). RESULTS: This disorder should be considered in any painful pelvic girdle syndrome or lower extremity pain. The hip is involved in 88% of cases. Symptoms develop in the third trimester of pregnancy, between the 26th and the 34th weeks. Magnetic resonance imaging (MRI) provides an early, accurate, and very specific diagnosis, although standard radiography continues to be the first-line diagnostic tool. Fracture occurs in 19% of patients. The etiology and pathophysiology remain unclear, although pregnancy itself appears to play a significant role in this disease. Although locoregional mechanical factors partly explain reflex sympathetic dystrophy. Hypertriglyceridemia appears to be a risk factor. This disorder develops independently, but the conclusion of pregnancy appears to be necessary for cure. Reflex sympathetic dystrophy does not appear to affect the course of the pregnancy. Indications for cesarean delivery remain obstetrical and should be discussed when a fracture is involved. Simple therapeutic management using gentle physical therapy provides rapid and complete recovery in 2-3 months. CONCLUSION: Reflex sympathetic dystrophy during pregnancy remains poorly understood and underestimated. Only joints of the inferior limbs are involved. MRI appears to be the best diagnostic tool. Pathogenesis remains unclear. Fractures are not rare. Treatment should be non-aggressive"

I have the whole paper on a PDF file if you're interested.

Hope this is helpful, and good luck!
Annie