Herbal Supplements in Pregnancy: Unexpected Results From a Multicentre Study

F. Facchinetti; G. Pedrielli, G. Benoni; M. Joppi; G. Verlato; G. Dante, S. Balduzzi; L. Cuzzolin


Hum Reprod. 2012;27(11):3161-3167. 

In This Article

Abstract and Introduction


Study Question How common is the use of herbal supplements during pregnancy and does it adversely affect the pregnancy outcome?
Summary Answer The use of herbal products during pregnancy is very common and daily almond oil spreading is associated with preterm birth (PTB).
What is Known and What This Paper ADDS Herbal drugs are often promoted as 'natural' and 'safe' and such claims attract pregnant women. More than a quarter of Italian pregnant women consume herbs every day for at least 3 months during pregnancy. We raise an alert over the habit of daily almond oil spreading since it seems to be associated with PTB.
Design A multicenter retrospective cohort study performed over a 15-month period.
Participants and Setting Seven hundred women interviewed within 3 days of childbirth, in three public hospitals in northern Italy.
Main Results and Role of Chance One hundred and eighty-nine women were considered 'regular users', since they consumed herbs every day, for at least 3 months. Almond oil, chamomile and fennel were the most commonly used herbs. Both length of gestation and birthweight were affected by herb consumption. Almond oil users showed more pre-term birth (29 of 189) than non-users (51 of 511). After adjusting for multiple pregnancies, smoking, advanced age and drug intake, almond oil users maintained an increased risk to give birth <37th week (odds ratio = 2.09, 95% confidence interval: 1.08–4.08).
Bias, Confounding and Other Reasons for Caution The association between daily spreading of almond oil and PTB only raises a hypothesis that requires confirmation in larger trials devoted to this topic. The relatively small sample size did not allow the investigation of other adverse pregnancy outcomes in herb users.
Generalizability to Other Populations The population under investigation did not significantly differ from the general population attending the same hospitals.
Study Funding/Competing Interest(S) No conflict of interest exists. The study has been supported by a public grant from the University of Modena and Reggio Emilia.
Trial Registration Number None


The use of herbal and complementary medical treatments has increased in many countries over the past decade. Women are more frequent users of complementary/alternative medicine than men (Lloyd and Hornsby, 2009; Brinkhaus et al., 2011). Multiple surveys have shown that women, especially those of white ethnicity, middle-age and with high levels of education and income, are more likely to be users of such 'alternative' medicines (Tesch, 2003).

Accordingly, companies that sell to Western markets now offer a significant number of herbal supplements with different intended purposes, some of which are specifically marketed to pregnant women. The rationale is 3-fold: (i) pregnancy is a condition that requires a greater intake of nutrients to assure adequate support to the new, growing organism; (ii) pregnancy is associated with minor complaints (e.g. nausea and constipation) that require relief but in some cases are not treated with conventional drugs that are believed to be harmful to the fetus and (iii) women and doctors trust that the best outcome in pregnancy can only be reached by removing hazards (e.g. anaemia or pregnancy-related complications) and that this goal can be achieved through a variety of different treatments.

Several studies conducted in Europe, the USA and Australia indicate that between 7 and 45% of pregnant women use herbal products (McFarlin et al., 1999; Forster et al., 2006; Louik et al., 2010; Nordeng et al., 2011). Pregnant women choose these types of treatments because they consider herbs to be natural compounds and therefore safer compared with conventional drugs (McKenna and McIntyre, 2006). However, although the adverse effects of certain herbal treatments are well documented, data on the safety of herbal consumption during pregnancy are very limited (Donald and Snodgrass, 2005).

Concerns about the outcome of pregnancy in herbal users are therefore quite justified. A previous study found no statistically significant differences related to herbal consumption, with the exception of a higher rate of neonates that were small for their gestational age among herb users (Ernst, 2002). Deeper analysis of the data suggested that a regular intake of chamomile and liquorice (taken from the beginning of pregnancy) increased episodes of threatening miscarriage and preterm labour.

The aim of the present study was to investigate the use of herbal products among a large sample of pregnant Italian women and verify its possible influence on pregnancy outcomes.