The Canadian dropped her fourth straight match Wednesday, losing 6-3, 4-6, 6-0 to Kristina Mladenovic of France in second-round action at the Aegon Classic.
Bouchard, who reached the Wimbledon final last year, became the seventh of the 16 seeds to fall at the tournament.
Bouchard, from Westmount, Que., was seeded fifth in Birmingham, but lost to Mladenovic for the second time in her last three matches. Mladenovic also eliminated Bouchard in the first round of the French Open last month.
Mladenovic had six aces to Bouchard's one, and saved nine of 10 break point chances.
"I felt very frustrated," Bouchard said. "But they told us that if we smack our rackets on the court we would get a huge fine — so perhaps that's why I kept my cool."
Bouchard has lost 10 of her last 11 matches in WTA and Fed Cup play combined, and has fallen out of the top 10 of the world rankings.
Elsewhere, former world No. 1s Victoria Azarenka and Ana Ivanovic departed from the tournament, with only Ivanovic confident of being ready for Wimbledon in 11 days.
Azarenka suffered another blow to her chances of reviving her faltering career when she was forced to withdraw with a left foot injury, while Ivanovic's title defence was ruined in the second round by Portuguese qualifier Michelle Larcher de Brito 6-4, 3-6, 7-6 (6).
Azarenka's foot injury is similar to the ailment which contributed to her fall from the world's top 20 more than 10 months ago, something which has prevented her from adding to her 17 titles in almost two years.
Although the forceful Belarusian is still only 25, with time in which to rebuild a top-level game which has so far earned her two Grand Slam titles, this latest setback will both cast doubt on her chances of doing well at Wimbledon, and add to her long-term worries.
Azarenka, nevertheless, tried to put a brave face on it.
"It's very disappointing for me to make this decision, but I tried to practice, and it just doesn't feel 100 per cent," she said. "I don't think it is the right time for me to take a risk right now, especially right before Wimbledon, and I need to make sure I have the best preparation possible."
With little time before Wimbledon, Azarenka looked like she would do well to be fit enough for the American hard-court season which follows a month later.
De Brito appeared to benefit from having played two matches already on grass, often hitting fiercely and with good timing, but Ivanovic seemed to have weathered the storm when she broke serve early in the final set and went to close the match out at 5-4.
However, de Brito played a fine game to break back, and thereafter discomforted the champion by swinging more freely. It earned her two match points at 6-4 in the tiebreaker, both of which Ivanovic saved well, only to double fault on the third at 7-6 down to lose her title.
"So many times I tried to do too much because I felt like, OK, it's fast, I have to do more, instead of just staying calm and executing my shots," the second-seeded Ivanovic said.
— With files from The Associated Press.