New mothers are being warned lifting and carrying baby car seats can put their postnatal recovery at risk.
First-stage seats are heavy and awkward for women left vulnerable after giving birth and can cause or worsen pelvic organ prolapse, physiotherapists said.
Nelly Brewer, 32, said she "thought her life was over" when she suffered a bladder prolapse after carrying her baby in his car seat. Manufacturers said they were limited on design and weight by regulations.
Cornwall physiotherapist Laura Cullen warned seats should ideally not be removed from the car in at least the first six to eight weeks after birth.
The Professional Network of Pelvic, Obstetric and Gynaecological Physiotherapy (POGP) said the seats were not well designed for carrying.
Amanda Savage, from POGP, said the seats were "not well designed to be a way of moving a baby around".
Ms Savage added women were "very, very vulnerable in those first few weeks" and they should be lifting as little as possible and strengthening support muscles. POGP advised putting a car seat on a lightweight frame with wheels and to use the car's Isofix fittings if possible to minimise twisting.
