A Labour MP is to spend just £21 on food for a week to see if it is possible to eat healthily while pregnant on income support.
Low birth weight is linked to a mother's nutrition
Helen Goodman, 48 and not pregnant, said she was concerned the benefits for pregnant women were insufficient.
She said a 24-year-old woman would receive £45.50 a week with which to pay for household bills, travel and clothing, leaving £21 for food.
"I think I'll get enough to eat but it won't be healthy," Ms Goodman added.
Starting on Monday, the MP said she expected "to have to eat porridge for breakfast", with a small glass of orange juice on four or five days and one piece of fruit included in her daily intake.
She said she might have to eat a biscuit instead of more fruit as "biscuits are cheaper".
Government guidelines suggest at least five portions of fruit or vegetable a day, with fish eaten at least twice a week.
"It's not possible with that budget to get five fruit and veg every day and I think I'll be well down on the amount of meat and fish," Ms Goodman added.
"So, I'll be able to get enough calories to keep going throughout the week, but, in terms of the quality of the diet, it won't be very good, and that's a real problem when you're pregnant."
Research shows a mother's poor nutrition can contribute to a baby's low birth weight.
This can then lead to problems later in life, including high blood pressure and learning difficulties.
"It will be fascinating to see whether it is possible to eat properly on Income Support, or whether we are storing up social problems for the future by failing to adequately support the poorest pregnant women," Ms Goodman said.