Many alternative medical practitioners and midwives use herbs and other supplements as a way to “tone” the uterine wall, which consists largely of muscle. Most of these herbs are used only in late pregnancy, because toning herbs can cause contractions that could cause miscarriage or premature labor. Take toning herbs only as directed by your medical practitioner and only at the times and in the quantities prescribed because miscarriage or other complications can occur from herb use.
Red raspberry leaf is one of the most frequently recommended uterine tonics, but proponents are divided on when it should be used. Some practitioners use this herb only in the third trimester, due to the risk of premature contractions. Others, like herbalist Susun Weed, claim this herb is not harmful in early pregnancy, but rather strengthens the uterus, preventing miscarriage. However, the overwhelming majority of miscarriages occur because of chromosomal abnormalities, which herbs cannot change. Other herbs used include squaw vine, blue cohosh and black cohosh. Do not take these herbs until the last few weeks of pregnancy, Weed warns.
Many midwives use herbs to decrease the length of labor and reduce the risk of Cesarean delivery. A double-blind, placebo controlled study conducted by researchers from the New South Wales Holistic Nurses Association found that consuming red raspberry leaf tablets starting at 32 weeks of pregnancy had little effect on labor duration. The study, published in the 2001 March-April issue of the “Journal of Midwifery and Women’s Health” found that the herb had no effect on the first stage of labor. The second stage, or pushing stage, of labor was shortened by an average of 9.59 minutes. The group who took the herb had a 19.3 percent use of forceps for delivery, while the placebo group needed forceps in 30.4 percent of cases.
Taking toning herbs in early pregnancy could cause contractions severe enough to cause a miscarriage. In labor, toning herbs could increase the strength of uterine contractions to the point of uterine rupture, particularly if you’ve had previous uterine surgery and have uterine scarring from fibroid removal or from a Cesarean delivery. Do not take herbs to tone the uterus without your medical practitioner’s approval. A review of literature on blue cohosh, used by as many as 64 percent of midwives in the United States to induce labor, published in the winter 2008 issue of the “Canadian Journal of Clinical Pharmacology” looked at the safety of the herb in pregnancy. Issues are potential pregnancy loss as well as possible birth defects, hypoxia in the newborn and perinatal stroke. Blue cohosh should not be used in pregnancy until studies on its safety have been conducted, note the researchers from the University of Toronto.
Despite their over-the-counter availability, the safety and efficacy of herbs in pregnancy remains unproven, Professor Edzard Ernst of the Department of Complementary Medicine at the University of Exeter warns. Avoiding supplements altogether is safest during pregnancy.