New Jersey will allow parents to select a third “nonbinary” gender option on state birth certificates starting February 1.

The legislation, which Gov. Phil Murphy signed into law in July 2018, would allow parents to select a third gender option for their children at birth and make it easier for people to change their gender on their birth certificates to match their preferred gender identity.

Before the law’s passage, New Jersey residents could only change their gender on their birth certificates if they had a letter of proof from a doctor confirming they had gender reassignment surgery or a letter from a certified mental health professional.

New Jersey is the fourth state to offer a third gender option on its birth certificates, joining three other states— California, Oregon, and Washington— which already have laws on the books allowing the third gender designation on state birth documents.

New York City also began allowing a gender neutral option on birth certificates, becoming the first local entity to pass a such a law.

Colorado, which recently began allowing residents to select “X” as a gender option on their driver’s licenses, is also deciding whether to include a third gender option for its birth certificates.