INS and placental insufficiency: Overweight and obesity are generally considered to be the risk factors for PTB due to the effects of placental insufficiency (Lassance et al., 2015; Pereira et al., 2015), inflammatory state (Gaillard et al., 2016), insulin sensitivity (Catalano et al., 1999) and cellular oxidative stress (Ballesteros-Guzman et al., 2019).