The lingerie model whose sexy pregnancy selfies turned her into an overnight internet sensation has already snapped the first photo of her trimmed and toned post-baby physique in 'granny panties' - just four days after giving birth to her son. Sarah Stage, a 30-year-old from Los Angeles, came under fire during her pregnancy for posting a string of selfies showing off her seemingly rock-hard abs, with some critics claiming that maintaining such a tiny figure could be damaging to her unborn child. But her son James Hunter was born at a healthy eight pounds and seven ounces last Tuesday. And only days after welcoming her son into the world, Sarah donned black bikini briefs and a patterned bra for her latest snaphsot, which she shared on Sunday with her 1.6 million Instagram followers. Scroll down for video . Proud mama: Underwear model and animal rights activist Sarah Stage shared this picture of her post-baby body on her Instagram account on Sunday - just four days after giving birth to her son James Hunter . Ready to go: The 30-year-old revealed that she gained 28lbs during her pregnancy, before noting that she was looking forward to getting back to the gym . '[Four] days post baby. Total pregnancy weight gain was 28 pounds. I'm excited to resume my workouts in [five] weeks! #JamesHunter #HealthyBaby #GrannyPanties,' captioned the picture, highlighting her weight gain, which fell within the 25 to 35lbs range that doctors doctors recommend for average-weight women. The image has earned more than 40,000 likes since it was posted, with many commenting on her post-baby body and her healthy son. 'Proud of you hot momma. You put the critics to rest. You look fabulous and have a handsome baby,' one person wrote, while another added: 'Holy moly! What a legend! The baby's weight puts all the critics to rest.' Over the weekend, Sarah also posted a heartwarming photo of herself wearing a long-sleeve floral romper as she cradled her newborn in his nursery, writing: 'So happy #JamesHunter.' Look of love: Sarah gazed adoringly at her newborn son in this photo she posted on Saturday . So precious: Sarah shared this adorable picture of her newborn baby, James Hunter, on Instagram . Meanwhile, the first pictures of her baby boy were released last week. Sarah shared the adorable snapshots on her Instagram page. One, which shows a close-up of her son's face, said: 'Love at first sight #jameshunter.' The first ever picture of James featured the newborn in an adorable fox outfit. Sarah commented on the photo: 'James Hunter (4/14/15) 8.7lbs/22 inches of HEALTHY baby! 'Thank you for the positive support throughout my journey... It's just beginning!!! #JamesHunter #Healthy' During her pregnancy many people commented that they felt Sarah's unusually trim figure could be damaging to her unborn child, but it seems their fears were unfounded. Baby bump: Sarah took her last pregnancy selfie (pictured) at 39 weeks on April 13, writing: 'Still waiting'. The 30-year-old gave birth James the next day . Baby boy: Sarah posted this precious picture of James to her Instagram on Friday commenting that it was 'love at first sight' Sarah confirmed to E! that she welcomed her son last Tuesday, revealing that her baby boy was  22 inches long at the time of his birth, adding: 'He's a big healthy boy and he got an APGAR score of eight to nine.' An APGAR score, which stands for Appearance, Pulse, Grimace, Activity, Respiration, is a quick method for assessing the health of a newborn, with scores of seven or above being considered normal. Sarah famously documented her changing figure via her Instagram page throughout her pregnancy, earning herself a huge number of fans - as well as a fair share of critics - in the process. Although the new mother came under fire last month as more and more critics spoke out against toned figure, their comments never stopped the model from sharing numerous photos of her toned abs. Nap time: In this gorgeous snap, James is seen sleeping in a giraffe costume . Last Tuesday Sarah shared a photo of two In-N-Out burgers, writing, 'Cravings,' although its not clear as to whether or not she enjoyed the meal before or after she gave birth. The lingerie-clad model snapped her last pregnancy selfie, which she captioned: 'Still waiting #9months [sic],' the day before she welcomed her son into the world. The snapshot of her in a black bra and thong underwear has been liked over 40,000 times since it was posted, and has earned nearly 4,000 comments. And Sarah, who is of European and Costa Rican descent, took to Instagram earlier this month to share a photo of growing belly during the last weeks of her of pregnancy, writing: '10 days until we meet #BabyJames.' But while a large number of comments made about Sarah's figure were critical, many women noted that they found Sarah's pregnancy body to be motivation to work out and live a healthy lifestyle. Model off duty: Sarah took plenty of selfies in her underwear throughout her pregnancy; here she posed at 37 weeks on March 27 . Haters gonna hate: Sarah, who came under fire for her being tiny and toned throughout her pregnancy, told her critics to unfollow her if they have a problem with her pictures . Toned physique: Sarah snapped this photo of herself flaunting her barely-there baby bump at 38 weeks on April 6 - 10 days before she was supposed to give birth to her son . 'I'm completely inspired to go to the gym first thing in the morning. You look absolutely gorgeous @sarahstage #amazing [sic],' one fan wrote. 'You look absolutely lovely. Hats off to you for being fit and taking care of yourself!' another added. 'If I ever have children, I'm inspired by you to treat my pregnancy the very same way. I'm sure James will be amazing! Congratulations.' Others compared their figures to Sarah's pregnancy body, with one woman writing: '10 days before giving birth?! Lord Jesus help us all! I look like this after dinner [sic].' 'I look like that after a good meal or two,' someone else commented. Meanwhile, some people suggested that her son would be as tiny as she is - although it has since been proved that there was no need to worry. Pregnancy pals: Sarah, then at 36 weeks, and her friend, at 39 weeks, compared their growing bellies for this playful picture on March 22 . Baby style: Sarah shared this cute photo of matching father and son Timberland boots before the birth of her son . 'Baby James will come out the size of her phone case,' one person commented, referencing the model's bear-shaped cell phone cover. When she's not sharing lingerie selfies, the new mother regularly shared pictures of her son's nursery and his future wardrobe. Last week, Sarah shared an adorable photo of matching father and baby sized Timberland boots, writing: 'Daddy & baby shoe game [sic].' And despite her critics, Sarah refused to hide her then-eight-month pregnant body in maternity clothes. Flaunt it: Sarah refused to wear baggy clothes during her pregnancy and instead opts for figure-hugging dresses like the one she wore in this picture on March 28 . Looking good: Sarah wore this sexy black dress on a 'date night' when she was 37 weeks pregnant on March 31, just two weeks before James was born . She shunned baggy dresses and instead dressed her bump in fitted Lycra or nothing at all. The fitness fanatic loves hitting the gym and often captures photos of herself working out, as well as following a healthy diet of quinoa, spinach and chicken. Clearly not letting her growing baby bump get in the way of her career, Sarah continued to proudly model whilst carrying. Two weeks ago, she shared a sexy snapshot of herself in black underwear and responded to her haters. 'BTW If you don't like my pics then unfollow me,' she wrote. 'I'm excited, happy and enjoying every second of my pregnancy. Can't wait to meet James! #NFG #37weeks [sic].'
Sarah Stage, 30, welcomed son James Hunter into the world last Tuesday .
The baby boy weighed eight pounds, seven ounces and was 22 inches long .
During her pregnancy Sarah was criticized for her trim figure and abs .