The short answer is: it's not easy.
Even though it is well-known that it is impossible to know a child's sex at birth based on visual inspection of the baby's genitals, and impossible to guess at their gender identity when they are born, the government continues to insist that children be assigned either M or F.
When a baby is born, if there is a medical practitioner (doctor, nurse, licensed midwife) who attends the birth, they are legally obliged to report the fact of the birth, and such details as the child's birth weight, place of birth, parent(s)...and their sex.
As the parent, you also have an obligation to file a Registration of Live Birth, which in turn asks you to report the infant's sex.
So, in order to avoid having your child's sex registered, you must convince your medical attendant not to specifiy 'm' or 'f'. And you must not do so yourself.
BUT - and here is a big BUT - if you do that, the Vital Statistics Agency will NOT give you a birth certificate for the baby. The Vital Statistics Act says specifically that a birth certificate has to show a child's sex.
Searyl Doty, a child whose birth was registered without a birth certificate, was initially refused, but later granted, medical services. Their health card was issued with a 'U' for unspecified. So I think it is likely that you would be able to be enrolled in the medical system. But, for example, you couldn't get a passport without a birth certificate.
If you would like further information or to discuss the options, feel free to give us a call.