It was a dilemma: Return a five-year-old to his mother with drug-riddled prison records or let his foster parents adopt him.

In a rare move, District Judge Shobha Nair overruled the objections and allowed the adoption based on the Adoption of Children Act.

But the natural parents have appealed against her order, she said while giving the grounds for her decision last week.

The judge said: "The straitened choice before the court was this - to endorse the request of foster parents to adopt a five-year-old twin boy they had been looking after since birth or to return him to his natural mother who is soon to complete an imprisonment term."

She added: "I allowed the adoption."

Born prematurely in September 2014, the boy had been fostered to the couple after he was discharged from hospital three months later.

This was because officers from the Child Protection Services (CPS) could not find anyone suitable among the mother's extended family to look after him.

Before she gave birth to the twins, the mother had been jailed for a drug-linked offence and released in February 2014. The father of the children was in jail for drug-related offences at the time of their birth.

At issue was the mother's commitment to caregiving of the twins, a concern the medical social worker at the KK Women's and Children's Hospital had raised to the CPS wing of the Ministry of Social and Family Development in November 2014.

The mother said she was unable to visit the twins regularly at the hospital because she was stressed as their father was then in prison.

She also had difficulty managing her older daughter, who was living in a children's home and having problems.

There were also difficulties in getting her to discuss long-term plans for the twins.

She and her husband agreed to foster care and signed the voluntary care agreement (VCA), giving the boy to one pair of foster parents and the twin girl to another.

They agreed to extend the VCA each time it expired and the last renewal was till December 2015.

In 2015, both were jailed again for drug-related offences and after their release in September and October 2015, remained uncontactable until January 2016. There were efforts to bring the twins and their natural parents together as a family in March 2016.

But the boy had, by then, formed a deep attachment to the foster family and displayed separation anxiety when taken to visit his parents.

From May 2016, the parents could not be contacted until November 2016, when they were arrested. She got a five-year jail sentence on conviction and is now in a halfway house, from which she is due to be discharged in August.

The father is awaiting trial on a drug trafficking charge that could carry the death sentence on conviction.

The mother, in her submissions objecting to adoption, expressed disbelief in having "to defend myself as a mother".

The father, referring to the CPS, said: "Whoever gives them this power - the child is ours and how dare they, like giving out chocolates, they are giving out our child."

The Director of Social Welfare, as Guardian-in-Adoption, investigated the application and supported the adoption.

The judge noted that the foster parents "only applied for adoption when notified by CPS that reunification efforts were not showing promise". She added: "The boy's story speaks of the devastating impact of drug use on families. It is a story that must allow for a better ending. I am of the view that the applicants are better equipped to ensure the best outcome for the boy's future."