Second-time mom Kourtney Kardashian is back in a bikini after gaining 45-pounds while pregnant with her daughter, Penelope.

Kardashian put on a tiny purple bikini, showing off a flat stomach and toned thighs, for an Us Weekly exclusive on her weight loss.

The new mom, who gave birth to her second baby in July, dropped 44 pounds in just six months and rocked a gold bikini for the cover of Us Weekly.

"This time, the focus is really on being a mom and being present, knowing my priorities," Kardashian told the magazine.

She used celebrity fitness guru Tracy Anderson's 90-minute dance-focused exercises and cut her portions to get back down to 105 pounds.

”It took me twice as long as last time but I feel healthy and really much better about it,” Kardashian wrote on her Celebuzz blog.

Kourtney gave her sister, Kim, some of the credit for her getting back in such great shape after the baby.

"If she wasn't scheduling the workouts, I probably wouldn't have been as motivated," she told E! News of Kim helping her keep to a strict exercise regimen.

With Kim set to give birth in July, Kourtney will likely be able to teach her a thing or two about motherhood -- something Kim has dissed in the past.

"Mom life is so torturous," Kim told Kourtney in a recent episode of E!'s "Kourtney and Kim Take Miami." Adding, "I have a whole new perspective on how boring and miserable your lives are." She went on to say that she would "literally die" if she were to have kids right now, but later apologized and blamed the outburst on her own fertility fears.

At the time, she didn't know she was pregnant with Kanye's baby.