SPRINGFIELD, N.J. — Leona Maguire of Ireland birdied four of her final six holes for a 3-under 68 and a one-shot lead over three players Friday at the halfway point of the KMPG Women’s PGA Championship at Baltusrol.

The winner Sunday in Michigan for her second LPGA title, the 28-year-old Maguire had five birdies and two bogeys in shooting her seventh straight round in the 60s, dating to the final round at the Mizuho Americas Open.

At 5-under 137 at Baltusrol, Maguire had her first halfway lead in a major. The former Duke star is ranked 12th in the world.

Mel Reid (67) of England, Xiyu Lin (71) of China and rookie Celine Borge (69) of Norway were tied for second, a shot ahead of first-round leader Lee-Anne Pace (73) of South Africa and fifth-ranked Minjee Lee of Australia, who pushed herself into the hunt for the second major with a 67.

“This is uncharted territory for me,” Maguire said. “Whatever happens this week, I’m sure I’ll learn a lot, and just sort of taking it one day at a time. I think this golf course demands that. I think you can’t think more than one shot ahead, let alone a hole or a round ahead.”

The Lower Course at Baltusrol has been the big winner this week. Through two rounds there were only 15 players under par and some of the biggest names in women’s golf won’t be around for the weekend, missing the cut at 5 over.

Still in contention are first-time winner Ruoning Yin of China at 2 under, two-time major winner Brooke Henderson of Canada and top-ranked Jin Young Ko of South Korea and Celine Boutier of France, along with Americans Gina Kim, Allisen Corpuz and Mina Harigae, all at 1 under.

Rose Zhang, who burst onto the women’s golf scene with a win at Mizuho in her first event as a professional, struggled and needed a birdie on her last hole to finish with a 74 and a 2-over score.

Among those who missed the cut were No. 2 Nelly Korda, No. 4 Lilia Vu, No. 6 Atthaya Thitikul of Thailand and No. 8 Georgia Hall of England. Lexi Thompson, ranked No. 9, needed four straight birdies late in her round to get to 4 over and make the weekend.