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Table 2 Summary of Results

From: Biophysical effects, safety and efficacy of raspberry leaf use in pregnancy: a systematic integrative review

Year, Authors (in chronological order) Design Participants Methods Preparation and dosage Analysis Effect on Uterus Effect on other physiology
1941, Burn & Whithell [22] Laboratory study: in vitro and in vivo Animal Cat, dog, rabbit and guinea pig uteri (and tissues), spleen, heart and blood vessels Variety of experiments on both isolated tissue and uteri in situ Extracts prepared 4 different ways, generally infusion of herb. Author stated dose was 1/100th part of human dose. unclear Relaxation effect occasionally followed by contraction Relaxes intestinal smooth muscle
1941, Whitehouse [23] Case series Human 3 postnatal women (Day 5, 7 and 8) Intrauterine ‘bag’ introduced to uterus to record contractions Oral dose - Uterine trace compared (no control) Relaxation effect, Aid irregular contractions Very slight fall in systolic pressure
1954, Becket, et al [24] Laboratory study Animal Virgin guinea pigs uterine and ilium, Frog rectums Compared different solutions pharmacological actions in isolated tissue A variety of preparations, no comparison to human consumption made unclear Some constituents were smooth muscle stimulants, others relaxed smooth muscle Smooth muscle relaxant to ilium and rectum
1970, Bamford, et al [25] Laboratory study Animal and human Rat uteri – both pregnant and non-pregnant Human uteri – both pregnant and non-pregnant Exposed uterine tissue to raspberry leaf and observed for 20 min Whole leaf used – crushed and infused with saline unclear Inhibited contractions of pregnant rats and contracted human uterine tissue in vitro in a coordinated fashion  
1999, Parsons, et al [26] Retrospective cohort study Human 108 pregnant women – 57 consumed raspberry leaf, 51 were in control group. Compared clinical outcomes for mother and infant Some had tea, some had tablets, some had both, one had tincture. Dose ranged from 1 to 8 cups or tablet per day. 13% commencing 8–28 weeks, 59% from 30 to 34 weeks, 28% from 35 to 39 weeks. Duration over a 1–32 week continuous period. Descriptive statistics, contingency tables and t-tests Shorten labour, ↑ term birth, ↓Artificial rupture of membranes, caesareans and instrumental birth No adverse effects.  
2001, Simpson, et al [16] RCT Human 192 pregnant women (primips) 96 in treatment group, 96 in placebo group Compared clinical outcomes for mother and infant, and side effects for cohort of women taking raspberry leaf in pregnancy with those not. Tablet from 32 weeks gestation for both raspberry leaf and placebo – only difference was addition of 1.2 g extract of raspberry leaf. Conservative dose (as first study of its kind) of 2.4 g / day – considered half dose. Descriptive & inferential statistical tests depending on variable measured ↓ second stage length, instrumental birth & ARM  
2002, Rojas-Vera, et al [27] Laboratory study Animal Guinea pig’s ileum, number not specified Ileum exposed to raspberry leaf for 5-10 min, washed and re-exposed. Relaxation activity compared 5 min before exposure to after exposure. Not described Dose response curve   Smooth muscle relaxant – but dependent on production process of extract of raspberry leaf
2009, Johnson, et al [28] RCT Animal Pregnant rats, number not specified Rats given either raspberry leaf or constituents, then offspring randomly selected checked for onset of puberty 10 mg / kg body weight once breeding confirmed until birth. Student t test and Mann-Whitney rank sum test and Fisher’s exact test ↑gestational length & accelerated reproduction development in offspring Transgenerational affect
2010, Zheng, et al [29] Laboratory study Animal Non-pregnant and pregnant rat uteri (number not specified) Non-pregnant uteri tissue was exposed to raspberry leave tea, capsules and extract. Based on the results of this only tea was used on pregnant uteri tissue accumulating every 12 min. Synthetic oxytocin was tested similarly. Authors stated highest concentrations, unlikely to be obtained through consumption by women. However, authors assessment of assumed dosage for humans was suggesting a cup of tea per day (less than common recommendations) and did not stipulate for how long. Concentration-effect curves Had more effect on pregnant uteri then non-pregnant uteri.
Excited contractions similar to oxytocin in pregnant tissue. Co-treatment of tea and oxytocin enhanced contractility more than oxytocin alone. Variable levels of response from different animals.
2011, Nordeng, et al [30] Retrospective cohort study Human 600 postnatal Norwegian women, 34 took raspberry leaf Interview using structured questionnaire during postnatal stay in hospital and a review of medical chart. Not identified Students t-test Pearson’s’ chi-square Linear regression
Logistic regression
↑ caesarean risk  
2011, Makaji, et al [31] RCT Animal Pregnant rats and their offspring, number not specified Nulliparous rats received raspberry leaf or variety of derivatives, as soon as breeding confirmed until they birthed. Male and female pups sacrifice from each litter for biopsy of liver 10 mg/kg body weight. Stated this was dose for humans, did not reference the point. SigmaStat P < .05   Female offspring had alterations in liver enzymes
2016, Cheang, et al [32] Case study Human
Pregnant woman with IDGDM
Hypoglycaemic effects followed use of tea and confirmed by withdrawal and reintroduction of raspberry leaf Consumed 2 cups of tea at 32 weeks gestation for 3 days. Naranjo algorithm   ↓ Blood glucose levels in a pregnant woman
2016, Bohata & Dostalak [33] Retrospective cohort study Human 315 primiparous women, unclear as to how many had raspberry leaf Women questioned after vaginal birth on methods used to prevent injury Not specified Descriptive statistics compared to control group using no preventative birth injury method   No effect on perineal injury