This was a multinational, cross-sectional, internet-based study. Invitations to participate in the project were extended to countries of the European Network of Teratology Information Services (ENTIS), Mothersafe in Australia, the Organization of Teratology Information Specialists (OTIS) in North and South America and other European institutions conducting public health research. The following countries agreed to participate: Australia, Austria, Canada, Croatia, Finland, France, Iceland, Italy, Norway, Poland, Russia, Serbia, Slovenia, Sweden, Switzerland, The Netherlands, United Kingdom, and USA. Data originating from some South and Central America countries (Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay and Venezuela) was also collected.
To minimize recall bias, women were eligible to participate if they were pregnant or had at least one child under one year of age. Study participants were categorized by reported country of residence at the time of the completion of the questionnaire. Country of residence was combined into six regions: Western Europe, Northern Europe, Eastern Europe, North America, South America and Australia.
An online self-completed questionnaire was developed and was open to the public via utilization of banners (invitations to participate in the study) on national websites and/or social networks commonly visited and consulted by pregnant women and/or new mothers. The websites also included Teratology Information Services (TISs), Organization for Teratology Information Services (OTIS) webpages, social networking sites, pregnancy forums and e-mail newsletters. Detailed information on recruitment locations and internet penetration rates are summarized in Additional file 1. The recruitment phase was between October 1 2011 and February 29 2012. The survey questionnaire was administered by Questback (http://www.questback.com). In each participating country, the questionnaire was accessible online for a period of two months.
The questionnaire was first developed in Norwegian and English. Translation into the relevant languages was performed; back-translation to English was done for specific parts of the questionnaire (i.e. psychometric scales) by two independent native speakers and/or translators. The questionnaire was translated into the following languages; Croatian, Dutch, Finnish, French, German, Icelandic, Italian, Norwegian, Polish, Russian, Serbian, Slovenian, Spanish and Swedish. A pilot phase of the study was carried out in September 2011 in Norway, Sweden, Finland and Italy (n = 47). The analysis of pilot data did not identify any major issues to the questionnaire. Collected data were scrutinized for the presence of potential duplicates (based on reported country of residency, socio-demographic characteristics, date and exact time of questionnaire completion) but none were identified. As a means of assessing external validity, socio-demographic and lifestyle characteristics of the questionnaire respondents was compared to those of the general birthing population in the corresponding country. National Statistics Bureau reports or national studies were used as the source for these comparisons (see Additional file 2).
Consent was obtained as follows: upon clicking on the link to the survey, each woman was presented with a description of the study and asked whether she was willing to participate. Informed consent was given by ticking a Yes response. Study approval was obtained from the Regional Ethic Committee, Region South-East in Norway and relevant Ethics Boards in each specific country. Permission to analyze the herbal medicine study data was also obtained from the Research Ethic Board of the Hospital for Sick Children, Toronto, Canada. All data were handled and stored anonymously.
The online questionnaire captured data on maternal health, socio-demographic, and lifestyle characteristics as well as use of herbal, and conventional medicines in pregnancy. The question “Did you take any herbal preparations during pregnancy (e.g. ginger, echinacea, valerian, cranberries)? If yes, please provide the name of all herbal preparations you have taken during pregnancy” was posed to all study participants. Women could report as free text entry the names of all herbal medicines used in pregnancy, along with the reason for its use, the period of use during pregnancy and the recommendation source(s). In addition, herbal medicine use could be reported under the specific questions about diseases and pregnancy-related health ailments. The relevant sections of the questionnaire are detailed in Additional file 3.
We defined herbal medicine according to the World Health Organization’s definition of any medicinal product based on herbs, herbal materials, herbal preparations and finished herbal products, that contain as active ingredients parts of plants, other plant materials, or combinations thereof . Medicinal products based on animal components, vitamins, minerals or homeopathic products were not considered as herbal medicines.
The responses to the herbal medicine text field were coded according to a pre-determined classification list of herbs by the national coordinator in each participating country. The pre-determined classification list was compiled by the study development team and included the herb’s common name, latin name and a 7 character specific code following the format of the World Health Organization’s Anatomical Therapeutic Chemical (ATC) code convention as a means to standardize the coding in the questionnaire database. When a product name representing a multi-herbal combination or combination product was entered, an internet search on the product name was performed and the botanical ingredient(s) coded according to the pre-determined classification list. When the woman reported using several herbal medicines and several reasons for use consecutively, the order of reporting was used to match the herbal medicine and its use. The form of the herbal medicine was not specifically requested (tea, tablet, or tincture). Period of use was defined as weeks 1 - 12 (first trimester), 13-24 weeks (second trimester) and week 25 to delivery (third trimester) and presented as selection options. Several recommendation sources could be checked off: my own choice, family/friends, physician, midwife/nurse, pharmacist, herbal shop staff, internet, magazine/media/etc or other.
Reasons for use were recorded and grouped into the following categories: preparation for labor, health promotion, nausea, anemia, cold/flu, urinary tract infections (UTIs), pain conditions, constipation, heartburn, gastrointestinal disorders/flatulence, sedative/sleeping problems, restless legs, water retention and prevention of premature delivery.
Maternal characteristics included age, marital status, educational level, mother tongue, employment status, parity, pregnancy intention, and information on use of assisted reproductive technology. Life-style characteristics included folic acid use and smoking status before and during pregnancy and alcohol consumption after awareness of pregnancy. Both disease specific and questions regarding pregnancy-related health ailments and how they were treated were included in the questionnaire. Participating women were first presented with a list of questions related to acute/short-term illnesses (e.g. nausea, UTIs) and chronic/long-term disorders (e.g. asthma, depression) and asked whether they suffered from these conditions during pregnancy. In cases with an affirmative response, women were questioned about medication use for each individual indication as free-text entry fields. Conventional medications were coded according to the World Health Organization’s ATC classification system .
Descriptive statistics were used to calculate the prevalence (%) and associated standard error (SE) of herbal medicine use in pregnancy, reasons for use and information sources. If a point estimate had a SE greater than 50%, an “*” was used and the point estimate was not reported. Univariate and multivariate logistic regression analysis was used to identify significant factors associated with herbal medicine use among study participants. The analyzed maternal characteristics included region of residence, age, parity, marital status, employment status, education level, use of folic acid prior to and/or during pregnancy, alcohol use after awareness of pregnancy and smoking during pregnancy. First the univariate logistic regression model was fit for all explanatory variables. From this, the multivariate model was built and adjusted for relevant covariates. A p-value of <0.05 was considered statistically significant. The Hosmer and Lemeshow test was used to assess goodness of fit of the final multivariate model . The data are presented as adjusted odds ratios (aOR) with 95% confidence intervals (CI). All statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM® SPSS® Statistics, Armonk, USA).