A 19-year-old pregnant woman has died in a bathtub after suffering an epileptic fit.

On Saturday night, 19-year-old Meg Walsh took a relaxing bath at the home of a friend in Newcastle, north of Sydney.

Meg – who was also 14 weeks pregnant – suffered an epileptic fit during her bath and slipped below the water’s surface, 9 News reports.

After knocking on the bathroom door to no response, a friend discovered Meg's lifeless body.

She pulled her from water and started performing CPR. Meg was declared dead after going into cardiac arrest at the hospital.

"I open the door and there she is lifeless in my bathtub. Cold, white, unresponsive, not breathing, blue lips, dead weight," the friend told 9 News of finding her friend.

"It was traumatising."

Meg's older sister, Jemma, told nine.com.au her sister had been diagnosed with epilepsy at age four and had been taking medication to control the condition.

The hormonal changes brought on by pregnancy had been affecting Meg's medication and treatment.

"When she fell pregnant, the medication started going through her body a lot quicker and they could not get the seizures under control," the 22-year-old said.

"The absent seizures would last about 20 seconds. Her whole body would go stiff and she would have this awful stare."

Meg also suffered grand mal seizures, but it is not known which type she suffered when she died on the weekend.

She said her younger sister was "so excited" after learning she had fallen pregnant and "could not wait to become a mother".

"She was only 14 weeks when she passed...but she had ideas for baby names," she said.

The father of Meg's child is devastated by the news.

"He is a mess," Jemma said.

"They weren't together but we have given him some of the ultrasound pictures Meg had."

Friends have also posted tributes to the "beautiful girl" on social media.

"Heaven gained two beautiful angels. Rest easy princess and the little life you carried inside you," one wrote.

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Meg's heartbroken family are hoping an autopsy will be able to determine her baby's gender so they can farewell the pair properly.

The family are hosting a fundraiser at the Tomago Bowling Club this Sunday in honour of Meg and her unborn child, with money raised going towards Meg's funeral costs and epilepsy research.

A GoFundMe campaign has also been launched to help raise funds for her funeral service.