Big baby expected

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My OB suspects a big baby is brewing...he says my belly is measuring 38 weeks which is where I am...but after it took him a bit to find the heartbeat he said he believed baby boy would potentially be on the bigger side and mentioned that if he still thought so in the next couple weeks that a c-section would be considered. Anyone else being told this or something like it or have in the past? I'm sort of unclear about why he thought that and regret not asking... Curious to hear your thoughts/experiences. Thanks 😀