Mother charged with murder after her second baby dies while co-sleeping.

Doctors warned Jessica Harper not to co-sleep. They made her watch safety videos, sign documents saying she knew of the dangers and urged her not to do it.

Jessica Harper while pregnant. Image via Facebook.

But she ignored them.

She ignored them, saying she knew best, and for the second tragic time a two-month-old baby son of hers has died “under similar circumstances.”

Police were called after two-month-old Hunter was found dead after co-sleeping with his mother and three-year-old-sister.

In 2011 Jessica Harper served 85 days jail time over the death of her two-month-old son Nicholas.

She had placed him on a couch, covered him in a blanket and gone upstairs in their home while her three other children, all aged under four, slept.

She then forgot about Nicholas and began texting friends.

Two hours later she returned to him where he lay blue and unresponsive on the couch.

His cause of death "positional asphyxiation."

But in a tragic turn of events in July this year the 28-year-old woke to her two-month-old son, Hunter, blue and unresponsive next to her in bed.

Harper, from Pennsylvania in the US, told police that her baby son slept in between her and her three-year-old daughter despite numerous warnings from doctors about co-sleeping.

In 2011 Jessica Harper served 85 days jail time over the death of her two-month-old son Nicholas. image via Facebook.

According to KTLA 5, when her youngest son was born Lancaster General Hospital made Harper read all safety conditions and sign a form that she acknowledged safe sleeping. She also had to watch a video on safe sleeping before she was discharged from the hospital.

Then again on May 20th Children and Youth advised her of the dangers of co-sleeping and when the baby was admitted to a pediatric hospital in June, Harper was again made to watch a video about safe sleeping.

Further to this police say two nurses spoke to her about the dangers of co-sleeping.

Police wrote that Harper’s paediatrician also repeatedly warned her of the dangers of co-sleeping.

But according to documents lodged six days before her son died, they said she dismissed the warnings about co-sleeping. Telling doctors she was “going to do it anyway.”

Authorities had been flagged about Harper after the death of Nicholas in 2011.

At the time Harper was charged with first-degree child abuse resulting in death and second-degree child abuse.

Detective Angel Valle wrote that when Nicolas died Harper “lost track of time and continued to text her friends for over two hours or more.”

“The defendant stated that during that time, she was selfish and neglectful of her son.”

Harper finally checked on Nicolas around 1 a.m. finding him"purple, cold and not breathing," court papers indicated at the time.

She eventually only served 85 days jail after medical examiners ruled the death was “accidental” asphyxiation.

Harper has been charged with murder. Image via KTLA 5.

But the death of Hunter has brought it all back again for the young mother.

The Lancaster County District Attorney's Office said in a statement that “Harper was warned numerous times by multiple medical professionals not to have the infant sleep in a bed next to her; Harper ignored those directives.”

Harper has now been charged with third-degree murder, involuntary manslaughter and endangering the welfare of a child. She was placed in Lancaster County Prison without bail. The Daily Beast reports the DA will seek 20-40 years for the murder charge.

The Daily Beast reports the DA will seek 20-40 years. Image via Facebook.

Harper's mother told The Daily Beast that she thought it was unfair the two cases were being linked.

“They were both asphyxiation, but one was on the couch, one was on the bed,” she said.

She said that it was because of the death of Nicholas that Harper co-slept.

“[Jessica] was fearful that she wouldn’t be there if he needed her, especially after what happened to the last one. She had been having bad dreams about it. The reason she did it, I truly believe, is that she thought he was safer with her than on his own.”

While experts caution parents not to co-sleep, studies show more than 50% of parents do.