APOA1 and hyperthyroidism: This negative feedback regulation mechanism might lead to continuous increases in the APOA1 levels in the serum of normal pregnant women but would result in no significant changes in the levels found in pregnant women with hyperthyroidism; as a result, pregnant women with hyperthyroidism have a lower serum APOA1 content than normal pregnant women at the second and third trimesters (Einbinder et al., 2018; Kelly et al., 2019; Li et al., 2019; Retnakaran et al., 2019).