The Black Swan star and her choreographer fiancé Benjamin Millepied have decided to wait for their new arrival before buying their baby things, and Portman said her caution is probably linked to her Jewish roots.
She told Access Hollywood, 'I think it's a Jewish thing to be kind of superstitious. You don't do any of the baby stuff before the baby arrives.'
The 29-year-old Oscar winner is rumoured to be expecting a baby boy, and said that so far, the pregnancy is going well.
She added, 'My back is not feeling great right now, sitting for so long. But everything's really great otherwise.'