Officials say they hope a normal service will resume as soon as possible at Basingstoke and North Hampshire Hospital.
The neonatal unit had to be temporarily relocated after an incident on Monday night, which led to pregnant mums being sent to Winchester instead yesterday.
Hampshire Hospitals NHS Foundation Trust says the care and treatment of babies on the unit has been unaffected, but it remains in a different part of the hospital.
The unit had to be evacuated from its normal location on Monday night. after steam was seen escaping from a maintenance area overnight.
Fire crews attended, but found no sign of a fire.
Hampshire Fire and Rescue Service says the alarm was caused by smoke from a pump in the pump room being pushed around the ventilation system.
Alex Whitfield, chief executive of Hampshire Hospitals NHS Foundation Trust, which runs Basingstoke and North Hampshire Hospital, Royal Hampshire County Hospital, in Winchester, and Andover War Memorial Hospital, said:
“The maintenance issues that led to the temporary relocation of the neonatal unit at Basingstoke and North Hampshire Hospital have now been resolved. The area is currently being deep cleaned and normal service will resume as soon as possible.
“The care and treatment of babies on the neonatal unit has been unaffected, but while it remains in a different area of the hospital, we are taking the extra precaution of asking women who have been under the care of a consultant during their pregnancy to birth at Royal Hampshire County Hospital.
“Obstetricians and paediatricians remain available at Basingstoke hospital and the maternity unit is open for women who have had midwife-led care throughout their pregnancy, with midwives working on our labour line service advising women appropriately when they call.
“Women who are not in labour but would like to speak to somebody about the options available should either call 07920 117968 or email Hilary.Goodman@hhft.nhs.uk.
“Further updates will be provided as they become available.”