Emma Wehrman, 30, from North Carolina, US, was inspired to create the onesies after her friend Kimberly Langston struggled to conceive.
She told Babble, Langston had been through a "heartbreaking" journey into parenthood, as her twin sons died at 24 weeks due to premature labour.
Langston is now 12 weeks' pregnant with her "miracle baby" and so Wehrman made the babygrows as a tribute to all her friend has been through.
"I was able to make these onesies for a friend that is finally pregnant with her little miracle baby," she wrote on the Facebook page for her Etsy shop on 13 February.
The onesies include adorable sayings: "Made with love and science", "The little embryo that could", and "I survived the ice age."
Wehrman decided to sell them on her Etsy store, which specialises in personalised items and clothing.
The onesies are priced at £9 each and can be purchased in sizes up to 12 months.