It is maddening that companies have such a blatant disregard for people's rights. This is absolutely not acceptable and she should contact HR if available.
The company has to conduct a risk assessment (which is sounds like they have done) and make reasonable adjustments. Failure to do so is discrimination under the Equality Act. If they are not able to make adjustments to make the work safe for the pregnant woman they must put her on paid leave until such a time that the risk is removed.
Taken from www.maternityaction.org.uk/advice-2/mums-dads-scenarios/pregnant/health-and-safety-during-pregnancy-and-on-return-to-work/
If your employer employs people of childbearing age and the work could involve a risk to pregnant women or new mothers, the general risk assessment must include a ‘specific’ risk assessment of risks to new and expectant mothers arising from any processes, working conditions, physical, biological and chemical agents. This includes women who have given birth in the last six months and for as long as they are breastfeeding. It also includes a woman who has had a stillbirth after the 24th week of pregnancy.
If the risk assessment reveals a risk, your employer must do all that is reasonable to remove it or prevent your exposure to it. Your employer must give you information on the risks and what action has been taken.
If there are still risks and you have notified your employer in writing (see the next section) that you are pregnant, breastfeeding or have given birth in the last six months, your employer must consider the risks and take action as follows:
Step 1: temporarily alter your working conditions or hours of work, if this is reasonable and avoids the risk, such as allowing extra breaks, ensuring that you can sit down and avoiding heavy lifting.
Step 2: If that is not possible, your employer must offer you suitable alternative work on terms and conditions that are not substantially less favourable than your original job.
Step 3: If there is no suitable alternative work, your employer must suspend you on full pay for as long as necessary to avoid the risk.