In the event her circumstances changed and she has been able to stay at home with Sage and her two other children aged 7 and 16, and she said Sage's health had not suffered.
But Ms Moroney said the Ministry of Health had reversed the position that it took on breastfeeding when her first bill on the issue was introduced in 2012.
"The first time the Ministry of Health said there was no connection between paid parental leave and increasing breastfeeding. This time round they acquiesced on that," she said.
She said the ministry had now "very conservatively" calculated that extending paid leave to six months would save about $3 million a year in health costs by enabling mothers to keep breastfeeding for longer.
She said she was confident the bill would pass its second reading due on May 25. Her earlier bill tied 60-60 so it did not proceed, but since then the Opposition has gained one extra seat through NZ First leader Winston Peter's win in last year's Northland byelection.
However Finance Minister Bill English's office said last month that the Government still planned to veto the bill on financial grounds because the immediate cost had not been authorised.
Ms Moroney said extending paid leave to 26 weeks would cost an extra $107 million a year, but it would also save $28 million a year in childcare subsidies, reduced unemployment benefits, reduced health costs and higher taxes.
She said the net cost was small compared with the $1 billion the Government has allowed for new spending in this month's Budget and $2.5 billion in next year's Budget, which is expected to be used for election-year tax cuts.
"There is no question that there is additional funding available, it's about whether they choose to spend it on families," she said.
Jacinta Fa'alili-Fidow, manager of the Taha Well Pacific Mother and Infant Service, told the gathering that extending paid leave to six months was important to reinforce the Ministry of Health recommendation that babies should be fed exclusively on breastmilk until six months if possible.
She said those who argued that parents chose to have babies and should pay for them ignored the fact that almost no one could afford to stop work in the current Auckland housing market without publicly funded support.
"The housing market is massively out of control," she said.
"Probably only 1 per cent can afford to have children in these circumstances. We need to invest in our families to have children, to have healthy, thriving children, and we can't make the excuse that it's not affordable."