THE EFFECT OF MULTIFETAL PREGNANCY REDUCTION ON SERUM RELAXIN

Objective: To determine the effect of multifetal pregnancy reduction o n circulating relaxin levels. Methods: Patients with multifetal pregna ncies had relaxin levels determined on the day of multifetal pregnancy reduction, after the procedure, and late in pregnancy. Results: Forty -eight women (26 presenting with three fetuses and 22 with four or mor e) were studied. All pregnancies followed some form of ovulation induc tion. All pregnancies (except for one, which was reduced to a single-t on) were reduced to twins. Pre-procedure, post-procedure and late-preg nancy relaxin levels were significantly higher in the in vitro fertili zation (IVF)-gamete intrafallopian transfer (GIFT) group compared with the human menopausal gonadotropin (hMG)-alone group (P <.05). The ini tial number of fetuses had no significant effect on relaxin levels. Al though post-procedure relaxin levels were significantly lower than pre -procedure levels (P =.002), relaxin levels continued to decrease thro ughout pregnancy, as evidenced by even lower levels later on (P =.0001 ). Conclusions: Serum relaxin levels were significantly higher in the IVF-GIFT group than in the hMG-alone group, which probably reflects mo re aggressive ovulation induction in the former. Because relaxin level s continued to decrease throughout pregnancy, the difference observed between pre- and post-procedure levels are not considered to be due to the procedure itself.