Prammanasudh was joined atop the leaderboard at Tartan Fields Golf Club by the soon-to-be retired Kristal Parker-Manzo, Jee Young Lee and Katie Futcher.
Prammanasudh started on the back nine and converted a birdie right away on the 10th. However, she ran off nine straight pars from there.
The 26-year-old birdied the second and came right back with a birdie on No. 3. A birdie on the seventh moved her to minus-4.
Prammanasudh made it two straight as she birdied the par-3 eighth. She ended her round with a third straight birdie on the ninth to gain a share of the lead.
'I actually got quite lucky on the first hole,' Prammanasudh admitted. 'I drove it through the fairway just a little bit so I was in the rough. I had a decent lie, but I caught it a little thin. It didn't look like it was going to make it over the water at all. It hit just short of the green and then jumped up. Luckily I made birdie, so that set the tone for the day.'
Parker-Manzo started on the 10th tee Thursday. She birdied that hole, then sank back-to-back birdies from the 14th. Parker-Manzo made the turn at minus-4 thanks to a birdie on the par-4 18th.
She dropped a shot at the first, but erased that error with a birdie on No. 5. Parker-Manzo closed with birdies on eight and nine to get in a minus-6.
Parker-Manzo said afterward that she is going to retire, again, after this event. She did the same two years ago due to an elbow injury, but returned once she was recovered.
'I don't know if you know, but this is supposed to be my last week. I'm retiring,' said Parker-Manzo, whose husband, Ken, caddied for her Thursday. 'It happened to me two years ago, too. I just wanted to go out and have some fun. I retired two years ago because I had a bad elbow. When I announced my retirement, I went out and finished fourth that week.
'I had some time off and got my elbow fixed and then I got the fever to play again. I've only made the cut in one event this year, out of seven. I haven't played bad, but I just haven't been cashing in. I think it's time to go home and be a mom.'
Lee also started on the back nine and got going with a birdie on the par-5 11th. She came right back to birdie the 12th and made it three straight at the 13th.
The Korean drained her fourth birdie on the par-3 15th. Around the turn, Lee stumbled to a bogey on the first. She atoned for that error with a birdie on the second.
Lee then birdied the fifth to get to minus-5. She followed that up with an eagle on the par-5 fourth. Lee faltered to a bogey on No. 6 and closed with three straight pars to remain in a tie atop the leaderboard.
Futcher, like the other three leaders, played the back nine in minus-1 with her birdie coming on the 16th. On the front nine, Futcher birdied the first. She poured in consecutive birdies from the third to move to 4 under.
The 25-year-old Futcher eagled the par-5 ninth, her last, to jump into a tie for the lead.
Among the nine players tied for 13th place -- just two strokes off the lead at 4-under-par 68 -- are Erica Blasberg, Paula Creamer, Ai Miyazato and Morgan Pressel.