Maternity breaks for women in STEM are an opportunity rather than a problem.

So says Dawn Bonfield, materials engineers and president of the Women's Engineering Society (WES), one of the organisations whose research has shown that 60 per cent of women returners to STEM careers faced barriers to doing so. 

"Over 90 per cent of those surveyed had got back to work, but there must be thousands who did not," says Bonfield.  "The cost of lost training and experience if a woman fails to return has been estimated at £200,000 each, so both women and employers lose out."

Lost women result in fewer at the top of STEM professions. "Studies show that organisations perform better with diversity at the top," says Bonfield. "Employers must stop thinking negatively about maternity leave and see it as a positive opportunity."

Simple but effective ways of helping women build a bridge back to full time work include flexible working, which 14 per cent of women in the survey said would help.

More companies could follow the lead of Thames Tideway Tunnel, which is constructing a 25 kilometre sewer tunnel in London. It introduced paid 12-week professional internships (now closed) for professionals returning to the workforce after two or more years. They were given assignments, coaching support and an internal mentor.

Engineering consultancy Atkins offers a returners course including help with adjusting to being a working parent and creating return plans such as departmental updates, handover plans and support networks.

Women on maternity leave could maintain their skills by undertaking projects for employers or could fill in any knowledge gaps to become chartered engineers, better equipping them to move up the ladder on return from a career break.

"Women on maternity leave who have older children could be STEM advocates among other parents, who are the major influence on a child's career choice," says Bonfield. "They could go into schools as STEM advocates or help access funding for equipment such as 3D printers to boost science teaching."

Professional bodies in the STEM sector could also help career break returners. "Benevolent funds usually used for retired members could be extended to help qualified women re-enter the STEM professions, and the body would gain new members," says Bonfield. "These women are a valuable asset."