By Nova Safo, CNN

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Editor's Note: On March 26th and 27th, the US Supreme Court will hear two key cases regarding same-sex marriage. Every Monday and Tuesday in March, CNN Radio will feature stories about issues related to same-sex marriage.

Listen to the full story in our player above, and join the conversation in our comments section below.

(CNN) - In Iowa, gay couples have been able to get legally married since 2009, when the state’s supreme court upheld a lower court ruling striking down a gay marriage ban.

But the Iowa Department of Public Health has refused to grant birth certificates that list both spouses in a gay marriage as the legal parents of newborn children. That decision has left families in legal limbo, and it led to a lawsuit that has thrust the gay rights debate right back to the state’s supreme court.

The couple involved in the supreme court case are Heather and Melissa Gartner. Even though they are legally married, Melissa Gartner’s name was erased from their daughter’s birth certificate. Heather Gartner, who was the biological mother, was the only one listed:

[6:21] "When you have somebody tell you that your marriage is not equal to your counterparts, because of who you’re married to, you can’t be a parent to this child – it’s very hurtful. I mean, honestly, when the first birth certificate came, it felt like someone had smacked you.”

Gay rights advocates say the Department of Public Health’s decision has left families in a precarious legal state. A birth certificate is a valuable document that legally ties a parent to a child, they argue, and without it, parents may be unable to perform even simple tasks such as checking their children in and out of school.

But the Iowa Department of Public Health has argued that it will provide a birth certificate naming both parents, once a parent that is not biologically related goes through a stepparent adoption. The department told the Iowa Supreme Court during oral arguments in December that since Melissa Gartner is not biologically related to Mackenzie, she cannot be listed on a birth certificate until she legally adopts her as a stepparent. The department argued it is required by law to provide an accurate birth certificate that records a child’s biological relatives.

A lower court ruled in favor of the Gartners, saying that once gay marriage became legal in Iowa, the Department of Public Health should have automatically begun to recognize both spouses as parents – as it does with legally married opposite-sex parents.

That is what other states have done, according to Angela Onwuachi-Willig, professor of law at the University of Iowa.

[9:49] “Every state that has addressed this issue has allowed both parents to be put on the birth certificate. We have no reason to believe that there’s any marriage equality state that is doing anything like what the Iowa Department of Public Health is doing.”

The Iowa supreme court is now considering the case, and there is no timeline as to when it might issue a ruling.

Listen to our story above to learn more about how families are affected by the “Iowa anomaly,” to meet the Gartners and another affected family, and to hear about the legal questions the Gartner’s case has raised.

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