From my medical herbalist perspective, it is a good question about juniper. But the question about use of juniper is a tough one to answer definitively. There is longstanding and traditional use for ceremonial and purification purposes as well as a digestive stimulant and food flavouring. Juniper leaf and berries have diuretic effects and have many aromatic pine-like constituents which can be useful as an antiseptic in urinary complaints. The essential oils in juniper can also provide anti-inflammatory effects. The problem is an association of the plant with reported effects of lowering fertility and stimulating miscarriage. Clinical studies in humans are practically non-existent, but studies in animals have suggested that implantation of a fertilised egg may be reduced. These physiological effects likely derive from essential oil constituents in juniper which stimulate uterine contractions and are irritant to the kidneys. Hence use is not advised in pregnancy (or breastfeeding) and long-term use is not recommended, especially in kidney conditions. However, it is likely that some concerns are based on confusion of common juniper (Juniperus communis) with savin (Juniperus sabina), a mountain-growing member of the Cupressus family notorious for use as an abortifacient. And a European assessment of juniper suggests there may have been confusion of toxicity with turpentine, a product of pine resins. Overall my view is that this is one of those plants that tests us because the therapeutic and toxic dosages can be so hard to differentiate. The juniper berries produce around 1% essential oil, and this is a highly concentrated extract which has to be used with care. Personally, I use juniper essential oil most often as an addition to external remedies - for example, it is an excellent insect repellent. In small quantities juniper berries provide a delightful flavouring (gin comes to mind) and
should be reasonably safe when used in curing. However, I have also seen reports of traditional use of as little as 5-6 berries in tea being drunk daily for contraceptive effects. So, without further evidence, I would have to err on the cautious side and advise against inclusion of juniper if pregnant, or planning to be pregnant.