Although the charges to which Williams pleaded guilty could bring her a prison term of up to 200 years, Lerner told Williams her actual sentence would be less because of the terms of her plea agreement with prosecutors.
Prosecutors, for example, waived a sentencing provision calling for a mandatory life term because Williams pleaded guilty to two counts of third-degree murder.
Williams' sentence will depend on the quality of her testimony in the eventual trial of Gosnell. Lerner did not set a sentencing date.
Williams, of Wilmington, a ninth-grade dropout, got through the hearing composed and assured. At one point she even laughed when Lerner joked about a gnat flying about.
But when the hearing ended, the impact of what will likely be a year or more in prison without bail before Gosnell's trial starts - followed by a prison sentence - hit her.
Williams' lip began to quiver and tears rolled down her cheeks.
"I don't know if I can do another year," the thin and pale woman said to defense attorney Stephen P. Patrizio, referring to the fact that she is segregated from other inmates for fear about her personal safety.
Patrizio tried to comfort her and was joined by Assistant District Attorneys Joanne Pescatore and Christine Wechsler, who walked over to the defense table.
"You did the right thing, Lynda, you did great," said Pescatore.
Lerner, who handles pretrial issues for all Philadelphia homicide cases, said he would hold a final pretrial hearing Nov. 17 in the Gosnell case. He will then assign the case to a trial judge.
Williams is the fifth of 10 people charged in the Gosnell case to plead guilty.
Among those still facing trial are Gosnell, who could be sentenced to death if found guilty of first-degree murder, and Gosnell's wife, Pearl, 50, who is charged with performing one late-term abortion and conspiracy.
According to the grand jury report, Gosnell hired Williams to work full-time at the West Philadelphia clinic in 2008. She had previously worked with him at Atlantic Women's Medical Services in Delaware.
Although originally hired to clean surgical instruments, the grand jury report said, she was soon working by Gosnell's side, anesthetizing abortion patients, performing ultrasounds, and dealing with babies born alive when Gosnell was not present.
Gosnell is accused of killing babies after live births by cutting their spinal cords with scissors. Williams' guilty plea involves one newborn - identified as "Baby C" - she killed with scissors 20 minutes after its birth in 2006 or 2007.
Williams also pleaded guilty to a count of third-degree murder in the Nov. 20, 2009, death of Karnamaya Mongar, a 41-year-old Virginia woman who came to the Gosnell clinic for an abortion and, according to the grand jury, was overdosed with anesthetics.
Contact staff writer Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or @joeslobo on Twitter.