'Born in the same womb, but different parents': Australia's ultra-rare twin case

A woman in Australia who became pregnant through both surrogacy and natural conception at the same time gave birth to two children with different biological parents on the same day, in a case that has only recently come to light. The two children grew in the same womb but are not genetically related to each other — an extraordinary circumstance that prompted a court to rule that while they are "gestational twins," they are not siblings under surrogacy law. Only the girl was recognized as the legal child of the couple who commissioned the surrogacy.

According to The Guardian, a Queensland woman identified as DZ agreed in April last year to serve as a surrogate for acquaintances BNJ and DRJ, and received the couple's embryo through in vitro fertilization (IVF).

About two weeks later, an ultrasound produced an unexpected result: DZ was carrying twins. Subsequent testing revealed that the girl was the biological child of the embryo donors, BNJ and DRJ, while the boy was the biological child of DZ and her partner FZ, conceived naturally.

Because DZ had also conceived naturally around the same time as the embryo transfer, two fetuses with different parents developed simultaneously in the same womb. The two children were delivered by cesarean section on the same day last November. There was no dispute between the two sets of parents over parentage, and each child has since been raised separately by their respective biological families.

The complication arose from Queensland's surrogacy legislation. Under current law, a parentage order cannot be issued for only one child among siblings born from the same pregnancy — if twins are born through a surrogacy arrangement, both children must have their legal parentage transferred to the same commissioning couple.

In this case, however, the two children had different biological parents from the outset: the girl belonged to the commissioning couple, and the boy to the surrogate and her partner.

The Queensland Children's Court ultimately ruled that while the two children were twins in the gestational sense, they did not constitute siblings as defined under surrogacy law. The court accordingly granted a parentage order recognizing BNJ and DRJ as the girl's legal parents.

The two families agreed to maintain ongoing contact so that the children can come to understand each other's existence and the unusual circumstances of their birth as they grow up. An independent consultant said in a written report submitted to the court that even though the children are being raised in separate households, the experience of being born together as twins could carry significant emotional and developmental meaning for both of them.

Judge Jodi Woodridge concluded that given the unique nature of the case, the two children could not be considered legal siblings, and that existing surrogacy law did not bar the parentage order from being granted. The Guardian noted that this is believed to be the first case in Australia in which children with different parents were born from the same pregnancy.