Will the lack of weight gain cause preterm birth?

Danni

I started the pregnancy overweight at 190lb (5ft4) in the first few months I went down to 165lb I'm now 20+1 weighing 170lb at night after eating lots all day! Baby weighs about 12oz according to the scan.

Both me and my husband were born a month early. Could the baby be born early?

Obviously I know there's always a chance but is it a bigger chance?