Family pressures, organisational culture and management styles, lack of opportunity, discrimination – there are any multitude of reasons why more women do not strive to break through into board-level positions.
But what is clear, according to British and U.S research, is that better coaching and encouragement of women by senior management, of whatever gender, can make a big difference in helping to shatter the glass ceiling.
A study by the UK's Institute for Employment Studies, funded by the Foundation of Coaching in New York, has identified the most common reasons why women in senior management positions in the US and Europe decide to accept or decline board-level jobs.
And with U.S consultancy Catalyst earlier this month arguing that women are still woefully represented at senior level, its findings are timely.
The Catalyst research, looking at women in Canadian firms, found that, despite correlations between strong corporate performance and women in leadership roles, Canadian women continued to be disproportionately underrepresented within the country's top 500 companies.
While the number of female corporate officers had grown by almost two percentage points over the past two years (a larger increase than that seen in the four years between 2002 and 2006), women still held fewer than a fifth of corporate officer positions, just slightly more than a tenth of senior leadership line roles and led just six per cent of the top organisations.
By contrast, women represented close to half of the labour force and almost 40 per cent of managerial positions, it argued.
The situation is not much better in the U.S, where women make up on average not quite 15 per cent of board members on Fortune 500 companies and, in the UK, hold just 11 per cent of FTSE-100 board directorships.
But blaming this ongoing gender imbalance at the top on discrimination would be wrong, cautioned the IES, as the reasons why women don't make it to the top, or even self-select themselves out of contention, can be much more complex.
While the legislative and socio-cultural context differed between countries, and some issues were more prominent in some countries than in others, a degree of consensus did emerge as to what were the key factors that impinged upon women's career progression, the study found.
This came up time and again as a factor in men's progression at the expense of women, said the IES, although whether this was simply down to perception or interpretations of behaviour rather than actual behaviour, and whether this made any difference anyway, was a moot point.
"The majority of women felt that there were some differences in style, and that this could lead to women being better, rather than worse, managers," the report argued.
"However, men were allowed more behavioural latitude than were women, while women can find themselves in a double-bind situation: there is pressure to adopt a more masculine management style at board level, but women who do so can find that this is judged as inappropriate for a woman and counts against them," it added.
Again, there was a common feeling among many of the women polled that policies and practices in many organisations had been developed on the assumption that senior, male officers would have a wife at home to support their lifestyle and that this could play against women.
"Executive roles are gendered masculine roles, which can lead some companies to develop 'boorish' cultures and some interviewees had taken a conscious decision to avoid organisations or sectors in which this was more likely to be the case," the research pointed out.
"In different organisations macho posturing could increase or decrease in the higher echelons; dependent upon this change, women could find that their position was made easier or more difficult as they rose through the ranks," it added.
Some women also found that assertive behaviour from women was viewed increasingly unfavourably at the higher organisational levels, something that, again, placed them in a "double bind".
If they were unassertive they did not gain development or progression, but if they were assertive then they are perceived negatively, and so less likely to progress.
There was a tendency for senior managers to recruit "in their own image" or to recruit individuals as similar as possible to the present job incumbents.
This served to make organisations resistant to change and to make it more difficult for women to be seen as appropriate potential employees, the IES said.
"Selection criteria that include overly-rigid requirements (such as specific experience) can make it difficult for women to be seen as appropriate candidates. Evidence shows that women recruited to boards are typically far more highly qualified than male board members," it pointed out.
Although women in all of the countries except Greece reported having experienced discrimination, it was not this so much as the assumptions made by senior colleagues that damaged women's career progression opportunities, the IES argued.
"Where there was discrimination it was more likely to be covert rather than overt. In particular, the discriminatory attitudes of males who currently hold board posts can often mean they overlook highly qualified and competent women when posts become vacant," the report added.
Women were less likely to be given the types of development opportunity that were viewed as necessary to support progression into higher levels of management and ultimately into board positions.
"Those women who had received the necessary development often reported having sought out and/or created the opportunities themselves," the report pointed out, somewhat damningly.
The fact that many occupations are strongly segregated along gender lines is well known, but what was less recognised was the fact that moving into a gender-segregated area could have a lasting and profound effect on career progression opportunities, the IES argued.
There was a strong suspicion among those polled that board members tended to be drawn predominantly from male-dominated backgrounds, such as finance and engineering.
Senior managers from areas such as human resources were viewed as lacking the appropriate experience and knowledge to fit them for service at board level.
"Given that more females than males move into areas such as HR, this view can severely curtail the opportunities for women to be selected for board membership," the report concluded.
Pioneers or tokens?
The women interviewed were, to some extent, pioneers, the IES conceded.
In many cases, however, they also felt they were tokens, used by their companies to present a more positive public image than might in reality be justified.
In some cases employers were "insultingly blatant" about choosing specific individuals to be a token "presence", argued the institute.
The difficulty here was that, whatever the rights or wrongs of such tokenism, women had little option but to concede that such appointments did allow them to gain experience that might otherwise not have been offered.
"Whether women arrive at senior positions through their own pioneering spirit or by being a token appointee, it is typically a lonely experience and the fact that such women are very much in the spotlight means that the position can be particularly stressful," the report pointed out.
The women polled believed they were judged far more on their appearance than were men.
This pressure to adopt an "appropriate" appearance that would not prompt stereotypical judgements from colleagues had led some women to take a strategic decision to radically alter their appearance.
Although such actions often made women feel as if they were wearing a "costume", they could be effective.
However, again, women often found it difficult to create the correct balance – although business suits increased credibility, they also potentially made a woman appear unfeminine and unapproachable and therefore led to less, rather than more, approval.
With countries such as Norway and Sweden leading the way in terms of national quotas for women in the boardroom (or at least the consideration of national quotas), this was now an issue deserving serious consideration, argued the IES, even though as an idea it was fraught with difficulties.
"While many interviewees believed that quotas were a good idea in theory, they have the disadvantage of effectively being a positive discrimination policy, with the potential for appointments to be seen as being made solely or primarily on grounds of gender rather than merit," it pointed out.
"Women believed that they themselves would feel insulted if they had been appointed as a 'quota woman' rather than on grounds of ability," it added.
Formal and informal networks had a large role to play in helping men gain influence and access to high-ranking positions, the IES concluded.
Women often found it difficult to break into male networks and there were few women's networks. Furthermore, the scarcity of women in senior positions meant any networks that were formed were unlikely to be as effective as those of men.
"Interviewees questioned whether it was worth trying to build up networks of women given that the majority of decision-makers are male. It was suggested that it would be more useful to help women develop the skills that would allow them to break into male networks," argued the report.
Childcare remained a major barrier to women's ability to participate in full at work, emphasised the IES.
Although availability of childcare was an issue in many countries, attitudes towards it could constitute just as much of a barrier too.
In Sweden, for example, although there are more progressive childcare policies and provision than that available in the other study countries, social attitudes lag behind the legislative environment and opinions about women who return to work soon after having a child are often negative.
In the other countries, the social attitudes and cultural norms regarding childcare were even more deeply ingrained.
Women in the five countries surveyed by the IES spoke of the sacrifices they had been forced to make, either in terms of their career or their family life.
"Many women with children were faced with the option of returning to work on a part-time basis only or not at all, and those who move to part-time working may find they are subsequently overlooked for promotion," it pointed out.
International experience was considered essential by many of the women interviewees to aid career progression.
While the increasing numbers of dual-career couples made it difficult for both women and men to move to take up international placements, none the less the view among those women polled was that international moves were significantly more difficult for women than for men.
"Whatever the practical difficulties, women were far less likely than men to be awarded such plum development opportunities," it argued.
More women suffered from a lack of self-confidence than did men, said the IES, and low self-confidence could hamper women's career progression in several ways.
"Women are less likely than men to make speculative job applications for posts for which they do not consider themselves fully qualified; self-confidence is also a factor in the significantly lower salaries negotiated, on average, by women compared to men. Women are more likely than men to be averse to self-promotion, which also impacts negatively on progression and rewards," it pointed out.
So, what was the answer? The IES study did not come to any hard and fast, or easy, solutions. But coaching for women in executive-level positions could be a key tool in helping them to progress.
Coaching, it argued, could help with confidence building, with providing a sounding board for ideas and for dealing with organisational cultures.
At the same time, it could improve women's networking capabilities, help them to identify values and goals, give them better access to development opportunities and assist them in making the right impression.
Finally, ongoing coaching could help women to cope with a new role, encourage them to achieve specific goals, help them to juggle any work-life balance and, ultimately, allow them to focus on what was personally important.
Coaching, it also suggested, should be offered as early as possible, as well as at key career transition points, and that coaching for men – as key gatekeepers to board-level positions – should focus on what they can do to help move more women into senior positions.