The safety of common herbs and spices during pregnancy is a frequent concern, prompting caution about dietary choices. Anise, derived from the plant Pimpinella anisum, is a widely used spice and traditional remedy found in global cuisine and folk medicine for centuries. Questions naturally arise about its potential effects on fetal development. This article evaluates the scientific evidence regarding anise use during pregnancy, focusing on its bioactive compounds and the current understanding of associated risks.
Identifying Anise and Related Compounds
Anise, or aniseed, is botanically known as Pimpinella anisum and is a member of the carrot family, Apiaceae. The spice is harvested from the small fruits of this plant, which are commonly used to flavor candies, drinks, and baked goods.
It is important to distinguish true Anise from Star Anise (Illicium verum), which comes from an entirely different tree native to China and is chemically similar, but botanically distinct. Japanese Star Anise (Illicium anisatum) is highly toxic and has caused serious poisoning when mistaken for the culinary variety.
The primary component responsible for Anise’s distinctive flavor and biological activity is trans-anethole, which typically constitutes between 75% and 90% of the essential oil. Anise also contains trace amounts of estragole, a structural isomer of anethole, which is a subject of toxicological concern.
Scientific Evaluation of Miscarriage Risk
The primary scientific concern regarding anise consumption during pregnancy stems from the estrogenic properties of its main compound, trans-anethole. Traditional knowledge has long associated aniseed with actions that can promote menstruation or facilitate childbirth, leading to its historical reputation as a potential abortifacient. Modern research has provided some mechanistic insight into these claims by demonstrating that anethole can bind to estrogen receptors.
In animal models, anethole has been shown to increase uterine weight in immature rats, confirming its estrogenic effect. The compound also exhibited an anti-implantation effect in pregnant rats, suggesting a potential for interference with the early stages of pregnancy. Furthermore, laboratory studies using a human feto-placental co-culture model have shown that both anethole and estragole can disrupt the normal process of steroidogenesis. Exposure to these compounds significantly increased the concentrations of various hormones, including estradiol and progesterone, indicating a potential for endocrine interference at the feto-placental barrier.
The presence of estragole is an additional concern, as this minor component is classified as a pro-carcinogen, and health authorities recommend minimizing exposure to it, especially in sensitive populations. Due to the lack of large-scale clinical trials in humans, regulatory bodies generally consider that there is limited reliable information available to confirm the safety of anise when consumed in medicinal or concentrated amounts during gestation.
Safety Guidelines for Consumption During Pregnancy
Based on current evidence, a clear distinction must be made between the culinary use of anise and its medicinal use. Anise is considered safe for consumption when used in the small amounts typically found in food preparations, such as in baked goods or seasoning. The trace quantities of anethole and estragole ingested from using the spice as a flavoring agent pose a negligible risk to fetal health.
The concern increases significantly when anise is consumed in medicinal or supplemental quantities, such as strong teas, concentrated extracts, or essential oils. These concentrated forms deliver a much higher dose of anethole and estragole, which can exceed safe levels due to their potential hormonal effects. The use of aniseed in amounts exceeding those found in food is explicitly not recommended during pregnancy.
Pregnant individuals should avoid all internal use of anise essential oil, as a single milliliter can contain enough concentrated compounds to cause toxicity. Before incorporating any herbal supplement or remedy, including anise tea, into a prenatal routine, it is strongly advised to consult with a healthcare provider. This consultation ensures that all dietary and supplementary choices are safe.