In total, 150 women have had their fertility treatment suspended while problems in the  lab run by Utrecht teaching hospital are sorted out, the AD said on Thursday.

The hospital originally said 84 women were affected but has now revised the figure upward. Four other hospitals make use of the UMC Utrecht’s laboratory and their patients too must now wait until the problems have been solved.

At the end of last year it emerged that mistakes at the fertility lab may mean the wrong sperm was used to fertilise the eggs of 26 different women.

The mistakes happened during a test tube baby technique known as ICSI which involves a sperm cell being directly injected into the egg. This meant that some sperm from the previous treatment remained in the equipment and could have entered the egg the next time the apparatus was used.

All ICSI treatment has now been halted while procedures are double checked. According to the AD, it will take a month before treatment is resumed.