Mace
Mandrake/Mayapple
Ma-Huang
Marijuana
Meadowsweet
Mistletoe
Motherwort
Mugwort: Famously contra-indicated (internally) during pregnancy because it can be a uterine stimulant (can cause contractions and possibly lead to miscarriage or preterm labor). It contains thujone, a neurotoxin linked to spontaneous abortion.
Myrrh (Commiphora myrrha): Considered an emmenagogue and an abortifacient.
Neem
Nettle Root
Oregon Grape Root
Osha Root
PN6 Capsules/Tea
Parsley: Parsley should be mostly avoided, if possible, during the first 3 months of pregnancy and then used sparingly as a culinary spice in the last 6 months of pregnancy. Large amounts of parsley oil (obtained from food use) can stimulate contractions of the uterine muscles and possibly result in pre-term labor. It can also cause unborn infants to develop a dangerous hemoglobin problem to his/her blood. This does not mean there is danger for you or your unborn child if you have already been consuming parsley. Use common sense. Large amounts of parsley are not recommended for breastfeeding mothers because it is known to decrease milk supply. Supplemental parsley can and does affect breastmilk supply drastically and is not recommended for any breastfeeding woman to ingest. If you have been taking supplemental parsley and notice your supply has decreased there are safe herbs you can take to rebuild it including fenugreek, fennel and goat's rue. Please discuss this with your local herbalist or ND.
Passionflower
Pau 'd Arco
Pennyroyal
Periwinkle
Pleurisy Root
Prickly Ash
Privet Fruit
Poke Root
Quassia Bark
Red Clover
Rhodiola Root
Rosemary Rue (Ruta graveolens)