There were 1,118 women in jail at the end of last year but the Singapore Prison Service declined to say how many of these women have children.
In 2012, a scheme was started to ensure that children of newly incarcerated women are cared for and given the help they need to cope, the prison service spokesman told The Sunday Times.
The Initiative for Incarcerated Mothers and Affected Children was started because mothers are the main caregivers and there may not be anyone to look after the children when they are behind bars.
In about three in four of these cases, grandparents are the ones looking after the children when their mothers are in jail.
The rest include other relatives, fathers and non-relatives such as the mothers' friends, said the Singapore After-Care Association which runs the scheme.
Cases where grandparents look after the children when their mothers are in jail.
Its social worker Evina Subani said: "Most of the time, the fathers are not around. Either they are divorced, not in the picture or they are also in jail."
Besides checking that there is someone to take care of the children, social workers would also assess if the children or their caregivers need more help to cope.
For example, the child may require counselling or the caregiver needs financial aid to get by.
Ms Subani said: "Children feel a very big sense of loss and grief as they are separated from their mothers. It is worse as many are not told their mothers are in jail as the mums or caregivers do not want their children to know out of shame."
If there is no relative or friend to care for the children, social workers would arrange for them to be placed in foster care, among other alternatives.
These children range from babies to teenagers, and the women have an average of three children each, Ms Subani said.
The scheme has reached out to about 1,600 children.