A mother and her baby daughter who were on Social Services' radar had been dead for at least a week before their bodies were discovered, an inquest has heard.
Joanne Thomas was found in her bed alongside four-month-old Harper at their terraced home in Troedyrhiw, South Wales, last July.
Aberdare Coroner's Court heard concerns had been raised weeks before, after 27-year-old Miss Thomas failed to take Harper for her injections.
A social worker told acting coroner Andrew Barkley he tried to visit Miss Thomas on three occasions before their bodies were found, as well as sending out letters and attempting to contact her family.
The bodies were eventually formally identified via dental records and DNA testing - with a top pathologist saying it was "impossible" to say who had died first.
Police later ruled out foul play, as well as discounting the possibility of carbon monoxide poisoning - after "slightly raised levels" were found in the blood of smoker Miss Thomas' blood and her baby.
A coroner was told Miss Thomas regularly complained of feeling unwell in the weeks leading up to her death and may have been vomiting blood.
Police say the deaths of a mother and baby from Merthyr Tydfil are not being treated as suspicious.
The bodies of Joanne Thomas, 27, and her four-month-old daughter Harper were discovered on Wednesday at an address in the village of Troedyrhiw.
Post-mortem examinations carried out to establish how they died have proved inconclusive so far and officers are awaiting the results of further tests, but there do not appear to be any suspicious circumstances.
A file of evidence is now being prepared for the Coroner.
Officers piecing together Joanne’s last movements still want to hear from anybody who think they may have seen her in the weeks leading up to Wednesday 3rd July.
Specially trained officers continue to provide support to the family at this difficult time.
The family of 27-year-old Joanne Thomas and her four-month-old baby Harper, whose bodies were discovered at an address in Church Street, Troedyrhiw on Wednesday have paid a short tribute to them.
They have described Joanne as being, “a bubbly, sociable, and kind hearted person. She was a loving and caring mother to her children. Joanne and baby Harper will be sorely missed by all her family and friends.”
The police investigation into the circumstances surrounding the incident is ongoing. Officers await the results of a Home Office Post Mortem to determine the cause of the deaths which at this stage are being treated as unexplained.
Detective Superintendent Paul Hurley, said: “I’d like to thank the local community for their co-operation so far and my appeal to them continues. We are still keen to hear from anyone who may have seen Joanne and baby Harper in the past few weeks to come forward.
"Our thoughts are with Joanne’s family. Specially trained officers are providing them with support at this difficult time.”Anyone with information can contact the incident room on 02920 527 303.