• London 2012 organisers confirm policy for newborn babies • 'Everyone must be a ticketholder, no matter how old they are'

London 2012 organisers are facing a backlash from prospective parents who have learned they will need tickets for their newborn babies – even if they were not conceived when the highly prized seats were bought.

The situation, which has been described as "ridiculous" and "bloody stupid" by angry ticketholders, has arisen because most tickets went on sale last April – 15 months before the Games.

Ticketholders, some of whom will have babies just weeks old and will be breastfeeding, have been told by the London Organising Committee of the Olympic and Paralympic Games (Locog) they can try to buy an additional ticket for their chosen event for the baby.

But with tickets at a premium for many events, and only a few "pay your age" concessionary tickets available, most parents will not be able to get a ticket or will have to pay the full price.

Ticketholder Rosalind Ereira said she was told she would have to call a hotline to try to buy an extra ticket to the dressage for her as-yet-unborn baby when the final 1.3m tickets go on sale in April.

"Everyone attending the Olympic Games must be a ticketholder, no matter how old they are," she was told. "Where available, pay your age tickets for children aged one and under would be charged at £1. You would need a full price ticket for the session in order for any children to accompany you on the day."

Ereira has contacted the Equality and Human Rights Commission (EHRC), which told her she may have a case for "indirect sex discrimination", as the policy is more likely to affect women than men.

The EHRC said: "A business must not do something which has a worse impact on you and on other people who share a particular protected characteristic such as gender than it has on people who do not share that characteristic. Unless the business can show that what they have done is objectively justified, this will be what is called indirect discrimination.

"It could be argued that women are more likely to have child caring responsibilities and thus this policy might have more of an impact for women, but as stated above the business might be able to justify this potential discrimination."

The policy has drawn a furious response from parents on the Mumsnet website in recent weeks. One woman described it as the "biggest ripoff in the history of London" while another said: "The whole thing is ridiculous, there are people who bought tickets before their babies were even conceived – how are they supposed to know to buy a ticket for a child that doesn't exist yet? There should be more complaining about this policy. It's nuts."

Another poster described the policy as "bloody stupid". She added: "The baby isn't taking up a seat, and if they're worried about fire regulations or whatever then it's not as if the baby isn't going to be with you at all times – essentially you should be counted as one person. The baby's not using the facilities on its own."

London 2012 organisers say the policy has been clear from the start of the ticket sales process and is not unusual for sporting venues. Overall, Locog is selling 6.6m tickets to the British public.

The process has been hit by a number of controversies, most recently when organisers were forced to close the ticket resale website for a week after technical problems.

In the face of the complaints, Locog on Tuesday night appeared to shift its position and said it would re-evaluate the situation, but stopped short of promising tickets for newborns.

"We want families and young people to come and enjoy the Games, which is why we created pay your age tickets at a third of sessions," said a spokeswoman. "Of course we understand that some new mums may want to take their babies to events they have tickets to and we will look at what we can do when the remaining tickets go on sale in April."

This headline has been changed since first publication