A New Zealand medical student who used a Taser to repeatedly shock a woman nearly nine months pregnant has been charged with attempted first-degree murder in the United States.

Christine Renee DeVaux - a 38-year-old medical student reportedly on leave from studies in New Zealand - is alleged to have snuck into the home of her boyfriend's pregnant daughter-in-law at the weekend.

She shot her with a Taser and beat her, causing the woman to go into labour, US authorities told the Washington Post.

Lynae Mattson, 29, and her almost full-term baby survived and were recovering at home near Damascus, about 65km northwest of Washington DC, police said.

DeVaux appeared to have worked in Wellington for Standards New Zealand in 2004, after coming here from the United States.

"We're lucky we're not here on a homicide case," Montgomery county deputy state attorney John Maloney said in court today.

DeVaux, charged with attempted murder and other counts, did not make bail because she was deemed a flight risk, given her strong contacts with New Zealand.

She holds a master's degree in economics from George Washington University, in Washington DC.

The victim's husband, an FBI agent, declined to comment. Police said there is no indication that the attack was related to his job.

The Washington Post reported DeVaux thought the victim, the victim's husband and the pregnancy were the source of problems between her and her own boyfriend, the victim's father-in-law.

According to court documents released today (NZ time) Mrs Mattson escaped by pulling her attacker's hair and running to a neighbour for help.

She spent about 12 hours in a hospital to receive treatment for injuries, including scratches and bruises, where doctors were able to prevent a premature birth.

In addition to a Taser probe and wiring, investigators found about 15m feet of wiring and cord and pepper spray inside the victim's home.

DeVaux was taken into custody between on Friday night at a Frederick motel, where she had rented a room.

DeVaux worked at the National Institute of Standards and Technology in Gaithersburg from 1997-2004 as a standards specialist, and has written papers touching on technical infrastructure in New Zealand.

Her preliminary hearing has been scheduled for July 2 in Montgomery County District Court.