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Limited evidenceWomen's health

Red Raspberry Leaf

A traditional "partus preparator" tea taken in late pregnancy, but the only decent randomised trial found no shortening of labour's first stage and only a ~10-minute effect on the second. It appears reasonably well tolerated, yet the evidence base is far too thin to call it effective.

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What the science says

  • Shortens labour Limited evidence

    The best-known RCT (192 low-risk nulliparous women, 1.2 g tablets twice daily from 32 weeks) found no significant shortening of the first stage of labour and only about a 9.6-minute reduction in the second stage — clinically trivial. A secondary finding of fewer forceps deliveries (roughly 19% vs 30%) was not a pre-specified primary outcome and has never been replicated.

  • Prevents post-term pregnancy or induces labour Limited evidence

    No controlled trial has shown that raspberry leaf brings on labour or reduces post-term induction rates. A 2021 systematic integrative review concluded that the biophysical mechanism in humans remains unestablished and that existing studies are too few, too small and too heterogeneous to support efficacy claims.

  • Relieves menstrual cramps Limited evidence

    This is an extrapolation from the same presumed uterine smooth-muscle effect, but there are no human trials of raspberry leaf for dysmenorrhoea at any dose. Animal tissue work is contradictory, with extracts relaxing uterine strips in some preparations and stimulating contractions in others.

Dosage & safety

Studied doseTrial dosing was 1.2 g of dried leaf in tablet form twice daily (2.4 g/day) beginning at 32 weeks' gestation. Traditional tea use is 1-3 cups/day made from 1-2 g dried leaf per cup, typically started in the third trimester. No dose-response work exists, and commercial capsules (300-500 mg) deliver well under the studied amount.
SafetyGenerally well tolerated in the available trials, with no increase in adverse maternal or neonatal outcomes reported in the 192-woman RCT — but that sample is far too small to detect uncommon harms. Reported side effects are mild: nausea, loose stools, and Braxton Hicks-type contractions. Because of the theoretical uterotonic action, it is conventionally avoided before the third trimester and in women with a history of precipitate labour, prior caesarean, placenta praevia, or any pregnancy under obstetric-led care. Raspberry leaf contains tannins that may reduce iron absorption if taken with meals, and there are isolated reports of hypoglycaemia, so caution is warranted in gestational diabetes. Discuss with a midwife or obstetrician before use in pregnancy.

How to take it

TimingConventionally started in the third trimester, around 32 weeks, and only after discussing it with your midwife or obstetrician.
With food?Take it away from iron-rich meals and iron supplements, since the tannins reduce iron absorption.
Worth knowingCommercial capsules at 300-500 mg deliver a small fraction of the 2.4 g/day used in the single trial, so a capsule label is nowhere near the studied dose.

Interactions

With other supplements

  • iron supplements

    The tannins in raspberry leaf bind non-heme iron and reduce its absorption. separate the tea or tablets from iron by about 2 hours

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does raspberry leaf tea shorten labour?

The evidence is limited. The one decent trial, in 192 first-time mothers, found red raspberry leaf did not shorten the first stage of labour and cut the second stage by only about 9.6 minutes, which is clinically trivial.

Can raspberry leaf tea induce labour?

No controlled trial shows red raspberry leaf brings on labour or reduces post-term inductions, and a 2021 review found the studies too few, too small and too heterogeneous to support efficacy.

When should I start raspberry leaf tea in pregnancy?

Red raspberry leaf is conventionally started in the third trimester, around 32 weeks, after discussing it with your midwife or obstetrician. It is usually avoided with a history of precipitate labour, prior caesarean or placenta praevia.

How much raspberry leaf should I take?

The single trial of red raspberry leaf used 1.2 g tablets twice daily (2.4 g/day) from 32 weeks, and traditional use is 1-3 cups of tea a day. Capsules at 300-500 mg deliver well under the studied amount.

Scientific references

Where to buy

Frontier Co-op, Organic Red Raspberry Leaf, 1.48 oz (42 g)

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