A court in the US state of Iowa has ordered that state’s Department of Public Health to issue a new birth certificate listing both members of a same-sex marriage as the legal parents of a 2-year-old girl. No mention will be made of the biological father.

Polk County District Judge Eliza Ovrom ordered the new birth certificate Wednesday as part of her ruling in a lawsuit brought by Melissa Gartner, 41, and Heather Gartner, 40.

The Des Moines couple sued the state when the Department refused in 2009 to list both names on the birth certificate of their daughter, Mackenzie.

Ovrom’s 12-page ruling did not declare a constitutional right for same-sex parents to be named automatically on newborns’ birth certificates.

However it accuses state officials of failing to correctly interpret older Iowa laws in light of the April 2009 Iowa Supreme Court decision that legalised same-sex marriages.

State administrators are bound by the 2009 case to interpret laws in a way that gives “full access to the institution of marriage,” Ovrom wrote.

“Pursuant to Varnum v. Brien, where a married woman gives birth to a baby conceived through use of an anonymous sperm donor, the Department of Public Health should place her same-sex spouse’s name on the child’s birth certificate without requiring the spouse to go through an adoption proceeding,” Ovrom concluded.

“Petitioners have proven the Department’s actions are in violation of law and based on an erroneous interpretation of the law.”

Iowa law says that if a woman is married, the husband must be legally deemed the father unless there’s a court order that says otherwise.

But state lawyers argued in the case that gender-specific parenting rights make it legally impossible to replace a “husband” with a same-sex “spouse.”

“If I had to summarise the department’s case in one sentence, it would be this: It is a biological impossibility for a woman to ever legally establish paternity of a child,” attorney Heather Adams argued at a hearing in November.

A public health spokeswoman on Wednesday said the department respected the limited scope of the ruling and was reviewing the order. The spokeswoman added that the department would decide whether to appeal the case within the next couple of weeks

Justice Ovrom’s ruling was based on provisions of Iowa law saying that an agency’s ruling can be legally reversed if it violates any provision of law or if it is based on an erroneous interpretation of a law “whose interpretation has not clearly been vested in the agency.”

She declined in light of those findings to rule on an argument that Iowa’s treatment of same-sex parents was unconstitutional.