
More than 1,000 women take legal action every year claiming they were sacked simply for being pregnant, figures show.
Other pregnant workers face demotion, hostility, pay cuts or are forced to work in unsafe conditions, the Equal Opportunities Commission (EOC) added.
A further study from shop workers union Usdaw found ignorance and lack of awareness was putting pregnant women and their unborn babies at risk.
The investigations have been published to mark National Pregnancy Week.
The BBC website has further information.