Visiting rules at Colchester and Clacton hospital's maternity wards have been "regrettably" changed as the third national coronavirus lockdown began.
The East Suffolk and North Essex Trust said the move was due to the "significant Coronavirus rates in our hospitals."
It means antenatal and postnatal ward visiting is suspended, apart from in exceptional or compassionate circumstances.
Only the person who is pregnant can attend maternity triage and antenatal appointments.
New mums will be able to have one birthing partner accompany them during labour.
One adult from the same household can also attend 12 and 20 week scans.
Giles Thorpe, chief nurse at the trust, said: “We fully understand these very difficult, but necessary decisions are upsetting for our expectant parents.
"We’d like to reassure expectant parents in north Essex they will still receive the best care and support on our maternity units.”
The trust's chief executive Nick Hulme described the move as a "regrettable but necessary step."
The trust said visiting to all wards remains suspended, apart from in exceptional or compassionate circumstances.
It said the decision will be kept under weekly review, based on case numbers.
Outpatients must attend appointments alone and those attending the emergency cannot be accompanied, unless they are a child or vulnerable adult.
All patients thought to be in the last week of life, either dying from coronavirus or other conditions, can have at least one visitor.
In exceptional circumstances up to four people will be able to visit.
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