Adopting a child is a "stringent and rigorous" process - with Matthew and Craig Scully-Hicks undergoing months of training, assessment and meetings.
Elsie was taken into care after her birth in November 2014, with the couple registering interest in becoming adopters days later.
They were visited in January 2015 by an adoption manager and attended training later that month.
There were four visits, including an assessment, by a social worker before their application to adopt was received by the Vale of Glamorgan Council.
Criminal records checks, medical examinations, social services checks and local authority checks were carried out before their case was reviewed by two social workers.
They were then presented to the Vale of Glamorgan adoption panel as prospective adopters and approved in July 2015.
Social workers for the couple and Elsie (pictured) carried out a home visit and they attended appointments to discuss her medical needs, personality, routine and care needs.
In August 2015, the match of Elsie and the couple was presented to the adoption panel and it was ratified in September, and they were introduced to her days later.
The introductions were reviewed by the adoption manager for the Vale, Valleys and Cardiff board, with the decision made to place Elsie with the couple.
She came to live at their home in Wellright Road, Fairwater, Cardiff, on September 10 - where the couple introduced her to a new routine and solid foods.
Following her placement, Elsie was observed during two visits to the family home by two social workers.
There was an adoption review at the house with social workers and an independent reviewing officer on September 29, and a health visitor visited on October 21.
Elsie attended a health visitor clinic on December 1, and was visited by a social worker the following day.
On December 17, Elsie's adoption was reviewed. A health visitor visited the family home four days later.
In January 2016, a social worker visited. Matthew Scully-Hicks and Elsie attended an adoption medical in February, with a social worker visit three days later.
A social worker visited in March, four days after Elsie had apparently fallen down the stairs, and an adoption review took place in April - as well as another social worker visit.
Elsie was formally adopted by Matthew and Craig Scully-Hicks on May 12 and died on May 29 - four days after collapsing at home.
Dr Justin Rogers, a lecturer in social work at the University of Bath, said: "We do not know enough about the details of the assessment of the adopters in this case and we will only understand more after a child practice review, the Welsh version of a serious case review, where lessons will be learned for practice.
"However, this desperately sad case does highlight that adoption is not some sort of panacea that can alleviate all child protection concerns.
"It shows risk and uncertainty remains when you are placing vulnerable infants, children and young people."
Dr Rogers said adoption was often prioritised by governments as a way to rescue children in need of protection.
In Wales, there were 385 adoptions in 2014 compared with 212 in 2007, he said.
Adoption can be a "very positive" placement choice for children and statistics show that only 3% of adoptions disrupt and fail.
However, research also suggests there are a "significant" number of adopters coping with complex and challenging circumstances, Dr Rogers added.
"The Government's prioritisation of adoption does not recognise this reality," he said.
"This shocking case in Cardiff shows that in child protection there are no guaranteed risk-free interventions."
The legal basis for adoption in Wales and England is the Adoption and Children Act 2002, which came into force in 2005.
Since November 2015, adoption services in Wales have been organised by the National Adoption Service for Wales.
Local authorities retain the statutory responsibility for "looked after" children, including identifying and care planning for those who will have an adoption plan.
A child placed for adoption continues to be a "looked after" child until an Adoption Order is granted by court.
Up until adoption, parental responsibility is shared between the local authority, birth-parents and the adopters.
The local authority is responsible for undertaking regular visits and reviewing placement until an adoption order is made - with these continuing if the child has particular support needs.
When a court grants an adoption order, all legal parental responsibility transfers to the adopter and an adoption certificate is issued naming the adopters as parents.
Since September 2015, the National Adoption Service has managed the Wales Adoption Register on behalf of the Welsh Government.
Copyright (c) Press Association Ltd. 2017, All Rights Reserved. Picture (c) South Wales Police / PA Wire.