Germany on Friday became the first European country to allow babies born with characteristics of both sexes to be officially registered as neither male nor female.
Under new legislation, the field for gender can be left blank on birth certificates, effectively creating a category for indeterminate sex in the public record.
Germany will soon also allow the gender field on passports be filled with an "X" instead of "M" or "F."
The new German law is intended to remove pressure on parents to quickly make a decision about controversial sex assignment surgeries for newborns, but some rights advocates said it does not go far enough.
Activists promoting the rights of so-called intersex people said they hoped the creation of a third gender option would open the door to broader changes that would limit genital surgery on newborns with both male and female characteristics.
"It's a first, important step in the right direction," said Lucie Veith, an intersex person from the northern German city of Hamburg.
But Veith said leaving the gender undefined on birth certificates was never the main lobbying point for the Association of Intersexed People in Germany, or others in the intersex community.
"Forbid cosmetic genital surgeries for newborns, that is our first demand," said Veith, who leads the organization.
The organization is calling for a ban on medically unnecessary surgeries until the child turns 16, so the intersex individual can decide whether to live as a man, woman, or neither.
Silvan Agius, policy director at ILGA Europe – a lesbian, gay, bisexual, trans and intersex rights group – said that even prior to having the choice of not recording a baby's gender, parents already had the option of saying, "'No, thank you very much, I don't want any surgery until my child can choose his or her gender.'"
Agius and other rights advocates fear that the new law would do nothing to change a society that operates largely on a gender-binary basis, with facilities such as male and female public toilets.
"There could be many other laws that could follow it and make it implementable and good," Agius said.
"My point is that if it remains as is ... then it's greatly deficient."
Experts estimate one in 1,500 to 2,000 births result in a baby of indeterminate gender, or both male and female gender features.
Surgeries such as clitoral reductions, removal of undescended testicles, and vaginoplasty, or the surgical creation of a vagina, can be performed to physically assign a gender.
According to a 2012 European Commission report on the topic, surgeries are performed on intersex babies and infants in many European countries without adequate informed consent by the patients.
The report also found that many intersex-born people are angry that these surgeries were performed without their consent.
In 2009, a regional court in Cologne in western Germany awarded more than 100,000 euros ($135,130) in damages to an intersex person who was raised as a boy, and whose uterus and womb were removed as a teenager.
The court found that the doctor had violated the person's health and self-determination, according to the EU Commission report.
Other countries that recognize a third gender on their passports include: Australia, Bangladesh, India, Nepal and New Zealand. Pakistan’s national identity cards began allowing the option for a third gender in 2011. Thailand’s military officially recognizes a third gender as well.