Whether parents use disposable or cloth nappies makes little difference to the environment, a report has concluded.
Some 675,000 children are born in the UK each year
The Environment Agency studied the impact of three types of nappy from their manufacture to their disposal.
Disposable nappies, bought by 95% of parents, led to 400,000 tonnes of waste dumped mainly at landfill sites.
But re-usable nappies affected the environment in other ways, such as by the water and energy used for washing and drying them, it found.
The agency says it is the most independent and thorough study yet carried out in the UK.
It compared the environmental impact of disposable, home-laundered flat cloth nappies and commercially-laundered cloth nappies delivered to the home.
The study was supported by surveys of more than 2,000 parents who were questioned on factors such as the number of daily nappy changes and the size of washing machine loads.
Tricia Henton, director of Environmental Protection at the Environment Agency said: "Although there is no substantial difference between the environmental impacts of the three systems studied, it does show where each system can be improved."
She said parents using reusable nappies can improve their impact on the environment by looking at how they wash them, such as using a bigger load at a lower temperature.
The study found most people washed nappies at 60C.
Ms Henton added that it was hoped manufacturers would use the study to improve the environmental performance of their products and the quantities going into landfill.
Tracy Stewart, director general of trade body the Absorbent Hygiene Products Manufactures Association (AHPMA), said she was delighted by the findings.
"It means parents will be able to make an informed choice and not be made to feel guilty about whatever type of nappy they use."
She said disposable nappies only made up 0.1% of rubbish at landfill sites, adding that the UK needed to look at the disposal of all its waste, considering alternatives such as composting and incineration.
She added that the AHPMA "questioned" why the government had spent £2.6m promoting cloth nappy schemes through the Waste and Resources Action Programme "in the absence of any proven overall environmental benefit".
Philip Ward, director of waste minimisation for WRAP, said: "Our Real Nappy Programme is aimed at reducing the 2.8bn disposable nappies sent to landfill each year and helping parents to make an informed choice.
"The Environment Agency's report itself calls for a reduction in the amount of disposable nappy waste being sent to landfill."