Why are herbal vaginal tightening creams not allowed or advisable during pregnancy?

Firstly, interested to know why I am not allowed to use herbal vaginal tightening cream or my previously regularly used vaginal weights whilst pregnant. There is no information about either anywhere I can find. Secondly, I am unable to find any information on how to reduce natural vaginal lubrication on the internet. Everything is about increasing this I have recently had all sorts of tests including hormone level checks (for being pregnant and also for general health check and results were fine). I have had this problem for several years even whilst is breastfeeding (which is supposed to cause the opposite problem). I have an appointment with my GP next week but would really prefer not discuss these things with him in person.