Not being truthful at home while having a baby (7)

I believe the answer is:

lyingin

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'home while having a baby' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'not being truthful at' is the wordplay.
'not being truthful' becomes 'lying' (I can't justify this - if you can you should believe this answer much more).
'at' becomes 'in' (synonymous in some cases - eg at school, in school).
'lying'+'in'='LYINGIN'

Can you help me to learn more?

(Another definition for lyingin that I've seen is " End of pregnancy".)

I've seen this clue in The Daily Express.

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