How to / is there a way to increase baby weight when in womb ?

I am FTM , 34.2 weeks currently & my OBGYN said baby is likely to be 2.75 kg approx at birth (he specifically said not to worry because he is not a big baby) , whereas my mom & mil keep insisting that baby should atleast be 3 kg -3.5 kg at birth .

While I read that ultrasound based projections can off by 500gm either ways , I am just worried that mine is not on the downside.

So is there really a way I can increase the baby weight now ? Or would it happen automatically ?

Also my HB has been dropping (9.3 at 30w to 8.8 at 33.6w) which is worrying me a lot but the OBGYN hasn't highlighted anything alarming . I would be seeing him at 34.5w but have already begun my iron supplements 😓

P:S - Birth weights in the family if it makes any sense from genetics point of view.

Hubby = 2.7kg born @ 34.3w

Hubby's bro = 2.85kg born @ 36.1w

Myself = 3.1kg born @ 40.2w

My bro = 3.4kg born @ 40.4w