Raspberry Leaf - why to wait until 32 weeks
We don't recommend you start drinking raspberry leaf tea until you're 32 weeks pregnant, but we thought it would be wise to say why we don't advise starting any earlier.
Essentially, this is because raspberry leaf has been used for millennia to help women prepare for labour. It is often written that it does this by making the muscles in the uterus contract - this is why some women experience braxton hicks contractions when they drink it. Studies on pregnant rat uterus's show this result clearly. However, it would appear that raspberry leaf can also make the uterine muscles relax too. This is shown in different animal studies, on non-pregnant uterine muscles, where a key chemical compound called 'fragarine' has a relaxant effect. No one is yet sure if the relaxing effect is strongest when not pregnant, and once pregnant is has a different impact. But the key thing is - that it is shown to affect your uterus and lead to positive birth outcomes.
It has historically been avoided until the later stages of pregnancy as you generally do not want to interfere with your uterus when a baby is on board! If you talk to your midwife, or doctor, they will likely recommend that you wait until 32, or even 36 weeks to drink the tea. Just to be safe.
Tests have been done on taking raspberry leaf from 32 weeks, showing very positive results.
The major one cited, is a double-blind, randomized, placebo-controlled trial consisting of 192 low-risk, nulliparous women who birthed their babies between May 1999 and February 2000 at a large tertiary-level hospital in Sydney, Australia - https://pubmed.ncbi.nlm.nih.gov/10754818/. It found that raspberry leaf, taken from 32 weeks’ gestation until labor, caused no adverse effects for mother or baby, and although it did not shorten labor, a lower rate of forceps deliveries between the treatment group and the control group (19.3% vs. 30.4%) was observed. Another study consisted of 108 mothers; 57 (52.8%) consumed raspberry leaf products, whereas 51 (47.2%) were in the control group.
These are great results from taking from 32 weeks.
In comparison, the only study available on taking raspberry leaf earlier in pregnancy looked at 57 Australian women who had used raspberry leaf products during pregnancy - https://pubmed.ncbi.nlm.nih.gov/10754818/. The majority (59%) of women began to take raspberry from 30 to 34 weeks onward, followed by 28% starting at 35 to 39 weeks. 13% (this is 7 women!) began using raspberry products between 8 and 28 weeks.
It was a tiny trial, but also showed good outcomes, in women having a lower likelihood of intervention in birth compared to those who didn't take raspberry leaf. BUT, most importantly, it showed (statistically) no benefit to consuming raspberry leaf earlier in pregnancy. At which point, we ask ourselves why you should be encouraged to take it earlier in pregnancy, and have it potentially contract and relax the uterus unnecessarily?
Whilst it may be bad business for us, we'd rather follow millenia of usage, and NHS guidelines to advise you to start from 32 weeks. There is no evidence to show that starting any earlier will give you more benefits, so we would play it safe.