It’s a popular theory that returning to work is the more stressful option for new mums, but a new survey shows it could be staying at home that takes a greater toll.

The survey of 60,000 women in the US by Gallup revealed stay-at-home mothers lag behind employed mothers in terms of their daily positive emotions.

When quizzed about their daily emotions, they were less likely to say they smiled or laughed, learned something interesting, or experienced enjoyment and happiness.

Not surprisingly, those stay-at-home mums who also struggled with a low income fared even worse - experiencing the highest rates of sadness, anger, and depression.

The 2012 Gallup Healthways Well-Being Index analysed adult women between the ages of 18 and 64, and showed that stay-at-home mums were much more likely to report having ever been diagnosed with depression than employed mums.

When asked about their emotions, 41 per cent of stay-at-home mums said they worried while only 34 per cent of employed mums said the same thing.

Half of all stay-at-home mums also said they were more likely to experience stress compared to only 48 per cent of employed mums. In fact, employed mums were about as emotionally well-off as working women with no kids.

But is it really about being a career woman? The authors say no.

“Stay-at-home moms at all income levels are worse off than employed moms in terms of sadness, anger, and depression, though they are the same as other women in most other aspects of emotional wellbeing.”

“Employed moms, however, are doing as well as employed women without children at home -- possibly revealing that formal employment, or perhaps the income associated with it, has emotional benefits for mothers.”