Is it ok for my sister to be nervous about her 2nd pregnancy?

Her and her husband lost their 1st child. The baby passed away in the womb at the 35 weeks, just a couple weeks after they had their baby shower. It's been 2 years later since the trauma and she's pregnant again.

She's nervous about it and once in a while still has nightmares about it. She is hoping that this time, it would be a successful pregnancy. She's both happy but very nervous.

Is it ok for my sister to be nervous about her 2nd pregnancy?
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