PLOD1 and ovarian hyperstimulation syndrome: No statistically significant differences were observed in the serum E2, LH and P4 levels between the treatment and control groups (P>0.05; Fig. 1) When comparing the serum E2 levels of the control patients with mild OHSS and moderate/severe OHSS on days 2, 5 and 8, the moderate or severe OHSS patients were shown to have significantly higher serum E2 levels (P<0.05) and a slower decline in the serum E2 level (Fig. 2).