The National Women's Council of Ireland (NWCI) made the call after reports that an inter-departmental group is considering putting forward new parental leave rules for couples.
Under measures revealed by the Irish Examiner on Monday, the Coalition is discussing whether to double the amount of leave a mother has after having a baby, and allowing her to split this increased time off with her partner.
It is believed the move will allow both parents to have a more equal responsibility for looking after their child; help women to return to work more easily if they so wish; prevent the need for babies to be placed in childcare facilities too soon; and make creches more affordable and accessible.
While welcoming the potential policy, which has not been signed off on and is one of a number due to be decided after an inter-departmental report in June, the NWCI said it must not dilute the existing guaranteed 26 weeks off for women.
Stressing that this existing leave must "remain intact", the council's director, Orla O'Connor, said it is important that any new policy builds on the current supports for parents.
"As it stands, Ireland is the only EU member state that provides no period of well-paid leave, so it is positive that the Government is looking at measures to ensure that Ireland catches up with other EU member states," said Ms O'Connor.
"It is, however, crucial that when parental leave is introduced it is paid, and that paid paternity leave is introduced as a separate entitlement ensuring maternity leave remains intact. It is equally important that the parental leave is introduced alongside accessible affordable, quality childcare.
Childcare costs in Ireland as a percentage of wages are the highest in the EU, over 50% of average wages, while the EU average is 23.8%. We need to see the incremental introduction of publicly subsidised childcare, starting with the introduction of a second free year pre-school year."
The council's comments mirror concerns raised by Justice Minister Frances Fitzgerald last September about the unexpected impact splitting parental leave could have on existing time off for new mothers. The minister said she had concerns the move could cause a "watering down" of maternity leave and mean "employers would place pressure on mothers to return early".