This is a controversial subject not because natural supplements are bad for pregnant women, but because they have not been proven to be safe. An easy assumption to make is that a natural herb or vitamin is going to be healthier for you than its synthetic counterpart. There is not evidence that supports that pharmaceutical medicines are safer. The problem is not knowing for certain whether or not a natural supplement will harm your baby.
Although herbs are all natural, this does not mean they are safe for pregnancy. Any time you are considering taking a supplement you need to speak to a medical professional first, whether it is a doctor or herbalist. Some herbs can cause disasterous effects like miscarriage, premature labour, contractions or injury to your baby.
There are herbs known to be unsafe for pregnancy that should be avoided entirely such as
Pennyroyal, Passion Flower, Ephedra, Goldenseal, Saw Palmetto, Dong Quai, Pay D’Arco, Roman Chamomile, Blue and Black Cohosh and Yohimbe.
While there are natural supplements that are considered safe or likely safe, it is still a gamble if there is no research. Talk to your doctor and get their input before trying anything new.