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April 2001; Volume 3; 25-26
By Adriane Fugh-Berman, MD
Red raspberry leaf (rubus idaeus, rubus strigosus) preparations commonly are used in pregnancy. A survey of 172 certified nurse midwives found that of the 90 midwives who used herbal preparations, 63% used red raspberry leaf.1
Herbals aimed at women consistently mention raspberry: "Tea of raspberry leaf as a daily drink is recommended by midwives worldwide for its strengthening, nutritive, and tonic effects on the womb, for mothers to be."2 "Brewed as a tea or infusion, Rubus is the best known, most widely used, and safest of all uterine/pregnancy tonic herbs."3
Should clinicians be concerned about the use of raspberry leaf by pregnant patients? Probably not. No adverse effects of raspberry leaf preparations have been reported, and a retrospective record review of women in Sydney, Australia, found no safety problems for women or their babies when raspberry leaf products were consumed during pregnancy.
Labor and birth outcomes of 57 women who had consumed raspberry leaf products during their pregnancy were compared with 51 controls (randomly selected from hospital records of women who stated they had not consumed raspberry leaf products). The groups were not significantly different in age, weight, parity, ethnicity, and whether they were receiving public or private care. Of the 57 women, 56.1% used raspberry leaf tea, 40.4% tablets, and 3.5% combined products (tea, tablets, and tincture).
Product dosages varied: 75.1% of tea drinkers consumed between one and three cups/d; the most common dose of tablets was six tablets/d (43.5%). Thirteen percent began using raspberry products between eight and 28 weeks, 59% from 30-34 weeks, and 28% from 35-39 weeks. Duration of consumption ranged from one to 32 weeks. Six women discontinued raspberry leaf products because of taste (2), diarrhea (1) Braxton-Hicks contractions (1), labor (1), and a decision to switch to castor oil (1).
Maternal safety outcomes assessed included maternal diastolic blood pressure before labor and, if the birth was vaginal, blood loss. Infant safety outcomes included duration of gestation, five-minute Apgar, and likelihood of babies being transferred to neonatal special care or intensive care. Labor outcomes included length of stages of labor, likelihood of medical augmentation, need for epidural, occurrence of meconium, and percentage of normal deliveries.4 There were no differences between groups in any outcomes. This was not a prospective safety trial, and a retrospective record review cannot provide definitive evidence of safety. Still, this study provides some measure of reassurance about the safety of raspberry leaf products.
Active compounds of raspberry (if there are any) are unknown. Raspberry leaf contains tannins (gallic and ellagic acids), bioflavonoids (rutin, the glycosides of quercetin and kaempferol), polypeptides, vitamin C, citric acid, oxalic acid, calcium, and ferric iron,5 none of which are known to affect pregnancy-related conditions.
A saline extract of raspberry leaves was reported to cause contractions lasting for a few minutes in strips of normal human pregnant uterus (10-16 weeks); there was no effect on strips of human non-pregnant uterus.6 The same extract was reported to inhibit contraction of uteri from pregnant rats, but had no effect on uteri from non-pregnant rats. In most strips of pregnant human or rat uteri that reacted to the extract, contractions were noted to become more regular and less frequent over a 20-minute period, as long as the extract stayed in contact with the tissue.
A 1954 report found that some aqueous fractions of raspberry leaves appear to stimulate smooth muscle contraction in guinea pig uterus and ileum.7 Another fraction had a spasmolytic effect on guinea pig ileum; intravenous injection of this fraction into anesthetized cats caused decreased blood pressure and bradycardia (an effect reversible by atropine).
The clinical implications of either of these studies are unclear. As previously noted, it is not known which compounds in raspberry leaf are pharmacologically active, let alone whether these compounds survive digestion in such a way as to have any end-organ effects.
In any case, there is no evidence of harm associated with consumption of raspberry leaf tea by pregnant patients; neither is there any evidence of efficacy.
1. McFarlin BL, et al. A national survey of herbal preparation use by nurse-midwives for labor stimulation. Review of the literature and recommendations for practice. J Nurse Midwifery 1999;44:205-216.
2. Potts B. Witches Heal. 2nd ed. Ann Arbor, MI: DuRêve Publications; 1988:54.
3. Weed S. Wise Woman Herbal for the Childbearing Year. Woodstock, NY: Ash Tree Publishing; 1986:18.
4 Parsons M, et al. Raspberry leaf and its effect on labour: Safety and efficacy. J Aust Coll Midwives 1999; 12:20-25.
5. Briggs CJ, Briggs K. Raspberry. Can Pharm J 1997: 41-43.
6. Bamford DS, et al. Raspberry leaf tea: A new aspect to an old problem. Br J Pharmacol 1970;40:161P-162P.
7. Beckett AH, et al. The active constituents of raspberry leaves: A preliminary investigation. J Pharm Pharmacol 1954;6:785-796.