Pregnancy is a transition period in a woman's life characterized by physiologic and psychological changes. In this period, many women report increased worries and anxiety [1]. Enhanced levels of anxiety during pregnancy may affect maternal blood flow [2] and contribute to adverse obstetric, fetal and neonatal outcomes [3, 4]. Risk factors for increased worries and anxiety are, for instance, single status and nulliparity [1]. Additionally, positive results from genetic screening or a prenatal diagnosis of fetal malformation increase anxiety in pregnant women [5, 6]. Even the suspicion of fetal abnormality conduces to strong feelings of anxiety, or worries [7, 8]. Thus, the assessment of anxiety and worries in pregnancy is an important issue that warrants adequate and validated instruments for assessment.

A widely used instrument for measuring anxiety is the Spielberger-State-Trait-Anxiety Inventory (STAI) [9], which has been used in numerous studies on pregnant women. Grant et al., for instance, examined the course of maternal anxiety across the transition to parenthood by using the STAI, whereas Fertl et al. used the STAI on a sample of women who had experienced prior miscarriages [10, 11]. The STAI is a validated instrument that is fairly short and easy to fill in. However, it should be taken into account that the STAI measures the extent of anxiety at a particular point in time and provides no information on what the pregnant woman is anxious about [12]. Furthermore, a study by Hundley et al. indicated that the STAI may be unstable around the time of delivery [13]. Green et al. developed the Cambridge Worry Scale (CWS) with the aim of assessing both the content and the extent of women's worries during pregnancy. The focus was on pregnancy-related and more general worries, which were regarded as non-pathological [12]. The CWS was developed for use in the "Cambridge Prenatal Screening Study" on a sample of 1072 women that was broadly representative of the UK childbearing population with regard to age, parity, education and socio-economic class [14]. The original English version of the CWS demonstrated satisfactory reliability and validity [12], which was also confirmed for its use in early pregnancy [15]. A Swedish version of the CWS has been validated by Georgsson Öhman et al. [16]. The importance of an instrument measuring worries in pregnancy is evidenced by the increasing use of the CWS in research projects over recent years [17–24].

Furthermore, the CWS has been adapted for use with other populations, such as parents of disabled children [25] and women with a family history of cancer [26].

To our knowledge, a German version of the CWS is not yet available. The aim of this study was to assess the extent and content of worries in pregnancy on a sample of women in Germany using a translated and adapted version of the Cambridge Worry Scale, and to evaluate the psychometric properties of the German version.

This study showed that the major worries reported by pregnant women were about giving birth and that something might be wrong with the baby. The internal consistency of the scale (0.80) was satisfactory, and we found a four-factor structure, similar to previous studies.

The study population was representative for the child-bearing population in the federal state of Baden-Württemberg with regard to age, smoking habits, obstetric risk factors and outcomes. Despite the fact that costs for antenatal classes are covered by medical insurance and most pregnant women take part in these classes [27], women of non-German nationality and housewives were underrepresented and skilled workers overrepresented, reflecting the relatively urban study region. In addition, nulliparae were overrepresented, which can be explained by the fact that multiparae already have child-bearing experience and thus participation rate in these classes is lower.

The overall mean score for trait anxiety (36.4) was comparable to the mean trait-anxiety scores in other studies of pregnant women, indicating that our sample was not generally more anxious than other similar populations: In a study by Green et al. the mean trait anxiety was 38.4 (+/- SD 8.1) in the 16^th gestational week [14] and in a study by Georgsson Öhman et al. it was 34.0 (+/- SD 8.5) in the 24^th gestational week [18].

This study showed that worries relating to the birth and to the possibility that something might be wrong with the baby were the major worries for participants. The worry relating to the baby's health ranked second in our study, whereas in comparable studies it ranked top [12, 14, 16]. The worry about the baby's health is strongly influenced by antenatal care, and women have high expectations of antenatal care in terms of possibilities for preventing fetal morbidity [34]. Most women take part in screening programs to be reassured that the baby is healthy and pregnancy is progressing normally [34, 35]. This is true for ultrasound examinations [36], and for other tests such as serum screening [37]. However, contrary to their expectations of reassurance, many women report suspicious findings in antenatal care, which may lead to further examinations and cause or increase worries [8].

An additional concern for women - not included as an item in the CWS used in this study - was worry about the reaction of older children to the newborn. This concern - already identified by Green et al. - can be added as an item if the scale is to be used in late pregnancy [12]. Women did not mention additional concerns regarding maternity services, contrary to the Swedish women that participated in the study by Georgsson Öhman et al. [16]. The findings of Georgsson Öhman et al. were probably specific for the Stockholm region at the time of the study, where two of six maternity units had closed for financial reasons [16].

The pretest of the questionnaire indicated that many women did not know how to score the response to the item "giving up work", probably because many women had already given up work before pregnancy or had never worked at all. However, participants may also have found it difficult to complete this item because it might reflect gender stereotypes and intrinsically devaluate the unpaid work of mothering. Further research should focus on whether it might be more appropriate to ask specifically about income security or maternity leave, as these factors also influence maternal psychological well-being. Cooklin et al., for instance, showed that nearly 18% of women experience pregnancy-related workplace discrimination or difficulty in negotiating maternity leave, and that experiencing adversity in the workplace during pregnancy was associated with increased depression and anxiety [38].

Cronbach's α coefficient for the German version of the CWS (0.80) was satisfactory and comparable to those reported for the original scale by Green et al. (between 0.76 and 0.79) [12] and that reported by Jomeen and Martin (0.80) [15]. Georgsson Öhman et al. also registered a similar α-value (0.81) for the Swedish CWS [16].

The principle component analysis revealed a four-factor structure, similar to the four-factor structure identified by Green et al. [12] and to the five-factor structure found by Jomeen and Martin [15]. The primary factor identified in this study on the socio-medical aspects of having a baby was consistent with that of the two studies reported above [12, 15]. We found that items concerning the baby's health and maternal and others' health loaded on two single factors, consistent with the findings of Jomeen and Martin [15], whereas in the study of Green these items loaded on one common factor [12]. Jomeen and Martin noted that the loading of health factors on two distinct factors appears to be commensurate with two health concepts, those of the health of the baby and those of others' health or "non-baby health" [15], which is confirmed by this study.

Items concerning socio-economic and relationship aspects loaded on a single factor in this study, whereas in previous studies they loaded on two separate factors [12, 15]. This difference is probably attributable to country-specific aspects. One way to interpret the difference is to take into account that in Germany the socio-economic situation of married couples may differ from Great Britain. One reason, for instance, can be found in the taxation system. While most countries rely on individual taxation, in Germany married couples can apply for joint taxation. This taxation system has been criticized as being a fiscal disincentive to the full-time employment of second-earners [39]. In fact, Germany represents one of the countries with the lowest share of households with two partners in full-time employment in Europe. The traditional male breadwinner model is still relatively common (in more than 40% of households), particularly in families with children [39]. However, such considerations require further research.

Convergent validity was examined by investigating the association between the total sum scores and the factor scores of the CWS and the state and trait anxiety of the STAI. We found a statistically significant moderate correlation between the total worry score and trait anxiety (r = 0.60). This represents moderate agreement, which shows that the CWS assesses a slightly different construct to the trait-anxiety questionnaire. This is important since it confirms that the CWS scores are not simply attributable to anxiety proneness [12]. Green et al. found a similar correlation between total CWS and trait anxiety [12]. Jomeen and Martin found a correlation of r = 0.38 between total CWS scores and anxiety [15], although the comparison is hampered by the fact that Jomeen and Martin used a different instrument, the Hospital Anxiety and Depression Scale for measuring anxiety [15]. We also found that the single factors of the CWS represented a different construct compared with state and trait anxiety but had the necessary overlap to be externally valid. The highest correlation was between the socio-medical factor and the state-, and trait-anxiety scores of the STAI. This might reflect the fact that the socio-medical factor integrates several aspects of anxiety that are covered by the STAI. Green et al. found a similar range of correlations between the factors assessed in the CWS and those in the STAI [12]. However, because of the different factor structure the findings of Green et al. are not directly comparable to the findings of this study.

This study has some limitations, attributable to the use of a cross-sectional design with a one-point measurement. The psychometric properties of the CWS described in this publication refer to a sample of women with a mean pregnancy week of 31. In the course of pregnancy, the extent of worries can be described as U-shaped, with a decrease in mid-pregnancy and an increase as birth approaches [14, 16, 40]. Thus, assessing the psychometric properties of the CWS on women in earlier or later pregnancy would probably lead to somewhat different findings.

The CWS is a flexible, context-specific tool which has allowed its adaptation for use in studies with other populations, such as parents of disabled children [25] and women with a family history of cancer [26]. In all of these, some of the core items such as money and housing were retained and pilot studies enabled the other main areas of concern to be adapted to suit the target group [12]. From a public health perspective, the CWS has considerable potential to be used as a context-specific, user-friendly tool in various populations. Further research is required to assess whether its use might also be useful to clinicians to better address women's concerns.

This study showed that the major concerns of pregnant women were related to worries about birth and the possibility that something might be wrong with the baby. The German version of CWS was well understood and easy to fill in. Internal consistency was satisfactory, and we found a four-factor structure, similar to previous studies. Tests of convergent validity showed that the German CWS represents a different construct when compared with state and trait anxiety but has the desired overlap. The German version of CWS represents a valuable tool for use in scientific studies and is also likely to be useful to clinicians.