A sprig of parsley can liven up your dinner plate -- but you may hesitate to eat it if you're pregnant. While pregnant women should not take large quantities of parsley oil, the amount found in parsley leaves used as a food garnish will not cause any harm, according to Dr. Lisa Rice of Creighton University Medical School. Talk to your doctor if you have concerns about your parsley intake.
The active ingredients that could affect a pregnancy in parsley include apiol and myristicin, both found in the oil of the plant. More than 30 varieties of parsley exist. Different types of parsley contain varying amounts of both substances. The seeds of the parsley plant contain more oils than the leaves.
At high doses, the oils in parsley can stimulate uterine contractions that can bring on a menstrual period. Parsley has a history of use as an abortifacient and could induce miscarriage or preterm labor in high doses. In Russia, a product containing 85 percent parsley juice has been used to induce labor, according to Drugs.com. Myristicin can cross the placenta to the fetus and may cause an increased heartbeat at high doses. Parsley oil in high doses can also cause a problem with the hemoglobin in your baby's blood, says obstetrician Gerald DiLeo, who writes for the Baby Zone website.
Parsley oil in high doses can have other side effects that have an indirect impact on you or your baby during pregnancy. Myristicin in parsley can have hallucinogenic effects, causing giddiness, loss of balance, kidney damage or seizures.
No safe dose in pregnancy has been established for parsley, but using parsley as a spice or garnish in cooking should not pose a danger. Avoid parsley tea, which is made from parsley seeds.