Cheeky, Bioforce's remedy is made from Sponge Cucumber and Heartseed and several other herbs, none of which were listed as contra-indicated in pregnancy while I was training.
With aromatherapy, therapists and aromatherapy books give conflicting information on whats suitable in pregnancy and whats not it, but most herbalists I think would say that luffa is not contraindicated.
However, lots of things are described as safe just because they have no known adverse effects, they may not completely safe for everyone but are described as such because no researchers or users have identified any associated problems.
Sorry if this isn't very helpful but remember that we don't know for sure ultrasound is safe for the baby. With one of my scans I received a letter saying they were safe for the mother and as far as they knew they were safe for the baby but more research needed to be done, yet very few of us refuse a scan, even in early pregnancy and until that letter everyone else had insisted they were safe.
Don't forget how many people drink and smoke all the way through pregnancy and lots of people do things they're not meant to in the early weeks before they know they have conceived and still go on to have normal healthy babies. I am not saying you shouldn't worry about taking risks, but that we never know for sure what is safe and what isn't. Luffa is a combination of some of the safest herbs and I would use it if I needed to.
With aromatherapy you do have conflicting advice so its hard to trust any essential oil but I would be surprised if any herbalist was afraid to prescribe Luffa in pregnancy. It would be interesting to see if Baboon agrees with me as she is also a herbalist