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 .
but her son james hunter was born at a healthy eight pounds and seven ounces last tuesday .
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 .