ACT Health says women and babies are never sent home before it is clinically appropriate.

But in a recent letter written by senior midwives at Canberra Hospital to ACT politicians, staff claimed patients were being sent home too early.

"Due to the lack of available beds, women and babies are discharged home inappropriately early with feeding, pain or health concerns," the letter read.

"Babies are often re-admitted to [the hospital] due to excessive weight-loss as a direct result of being sent home early due to hospital capacity.

"Staff are unable to provide adequate breastfeeding support in the brief period they are in the hospital and Midcall, the hospital postnatal home visiting service has been substantially reduced."

The data showed the average length of stay at Canberra Hospital after a vaginal delivery was 2.1 days, while at Calvary Public Hospital it was 1.9 days. The peer average for similar hospitals was 2.3 days for both.

The data relates to women who stayed one or more nights for a vaginal delivery without complications.

Ten per cent of mothers at Calvary and 8 per cent at Canberra Hospital did not stay overnight after a vaginal birth.

Births have increased at Canberra Hospital by 22 per cent since 2011-12, while the length of stay slightly decreased.

Births slightly decreased during the same period at Calvary Hospital but the length of stay has dropped significantly from 2.5 to 1.9 days.

The Royal Prince Alfred Hospital in Sydney - which has the same "major hopsital" classification as Canberra Hospital - had the longest average length of stay for major hospitals at three days.

Only 2 per cent of women at the hospital were discharged without staying a night at the hospital.

When taking into account nearby regional hospitals, women stayed significantly longer at Queanbeyan Hospital, where the average stay was 2.7 days and only 2 per cent of women left without staying a night.

Goulburn Hospital had an average stay of 2.6 days and 2 per cent left without staying a night.

The Australian Medical Association has expressed concern women are being pushed out too quickly, with the trend to decreased postpartum hospital stays in recent decades.

The association has raised concerns the effect that may have on breastfeeding and gaining support for things like post natal depression.

"Mothers can be discharged as early as six to 48 hours after delivery, long before their milk has come in," the association's position statement said.

"Women should only be discharged from hospital when they are physically and emotionally ready to return home, recognising that flexibility will be required to accommodate the unique circumstances of each family."

The executive director of women, youth and children at Canberra Hospital, Elizabeth Chatham, said women or babies were not sent home before it was clinically appropriate.

"We also want to be clear that women and babies are not sent home until they are well," she said.

"After being discharged, women receive midwifery support through the Midcall Domiciliary Midwifery Program and our Maternal and Child Health services to ensure newborns are developing as expected."