The use of nitrous oxide has been suspended with immediate effect at Ipswich Hospital until new ventilation can be fitted.
Dr Giles Thorpe, chief nurse at East Suffolk and North Essex NHS Foundation Trust, said they had tested the levels of nitrous oxide in their maternity services following concerns about high levels at Basildon Hospital.
He added that nitrous oxide is piped at Colchester Hospital's maternity unit with extraction units in place, but this is not the case at Ipswich Hospital.
A specialist testing company checked the Ipswich birthing rooms and found that there are some areas "above the 'safe' levels identified in national guidance."
Dr Thorpe said they have placed an immediate order for 13 mobile units known as scavengers to remove any excess nitrous oxide in the air, but it is likely to be five to seven days before they arrive.
He added: "Therefore, we have taken the decision to protect all of our staff by stopping the use of nitrous oxide at Ipswich maternity unit until the mobile units are in place."
Dr Thorpe emphasised that nitrous oxide is not harmful to pregnant people, but that better ventilation would help reduce residual levels left in the air after it has been used.
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