Methodological limitations
This study has a number of limitations that should be considered before drawing conclusions. The sample of women was heterogenous: all women were white and two thirds were educated to degree level or above, despite our attempts to recruit a diverse sample of women. Similarly, the health professionals interviewed were all obstetricians. More research is therefore needed to determine the views of women from ethnic minority groups and other maternity care professionals, such as midwives, who help manage impacted fetal head. A second limitation is the challenge of presenting two different, complex RCT designs to participants. Although participants had a good understanding of the different techniques, some of the women found the trial designs hard to understand, especially if they had a limited understanding of research methods and procedures. To address this we used a visual diagram (Fig. 