Eve Carlile describes the move as "practically really helpful, and ideologically great".
The 33-year-old lives with her partner Rosalind Carlile, 34, in Scunthorpe with their two boys, aged four and one.
The two adults have been together for 12 years and in a civil partnership for the last three.
Both their children were conceived by Rosalind using an anonymous sperm donor.
"It's brilliant that women in our situation will have full legal rights for the co-parent from the beginning," Eve said. "It's fantastically good news.
"We didn't conceive our children together, but we did conceive of them.
"Hopefully it will have a positive effect on society's view of lesbian and gay people, because the government are basically saying that we're OK, and perhaps people who are not gay will begin to think the same."
The media coverage will help get the point across that our lifestyle is 'normal', for want of a better word, and nothing to get excited about
The new law only counts for women receiving fertility treatment on or after 6 April of this year.
For women like Eve, this means that she has to adopt the children, and she has begun that procedure.
"It's a little bit farcical, because we have to be seen by a social worker who has to take time away from children who are at risk to examine my case," she said.
"I'm not a step-parent but I'm regarded as such in the adoption process. Understandably, the social workers put cases like ours at the bottom of their list.
"While I'm pleased that this new law has come in for couples in the future, it's a shame that it won't have a positive effect on people like us, that it won't mean our case will be fast-tracked or anything."
Eve also said the new law "cannot be anything other than a good thing" in the advancement of gay issues among public opinion.
"The media coverage will help get the point across that our lifestyle is 'normal', for want of a better word, and nothing to get excited about.
"But I don't think many people are homophobic about our type of family. Certainly we've never experienced any homophobia, at school or in church, anywhere.
"The new law means that as the children attend school and hospital, a woman in my situation can say that she is the other parent."
Rosalind echoes her partner's sentiment, saying the previous circumstances have been "such a pain".
She added: "This whole adoption procedure is going to be long and drawn out and it's a waste time and resources.
"Unfortunately it would be an administrative nightmare for the government to go back and apply the law retrospectively, but you would think they would fast-track cases such as ours, for people who have had fertility treatment in the last few years."