BACK PAIN IN IN-VITRO FERTILIZED AND SPONTANEOUS PREGNANCIES

The influence of ovarian stimulation in in-vitro fertilization (IVF) o n the prevalence of back pain with onset during pregnancy was studied in 31 women who became pregnant after IVF treatment and compared with that of 200 spontaneously pregnant women. A two times higher prevalenc e rate of sacral pain in late pregnancy was reported among IVF pregnan t women (P < 0.0001), as well as a significantly higher prevalence rat e of positive results of pelvic pain provocation tests performed in la te pregnancy (0.0001 less than or equal to P less than or equal to 0.0 15), as compared with that of the spontaneously pregnant women. Among the IVF pregnant women, there was a significant positive correlation b etween relaxin concentrations in early pregnancy and the outcome of pe lvic pain provocation tests (0.44 less than or equal to r less than or equal to 0.51, P < 0.05), In addition, the serum relaxin concentratio n was the factor that best explained differences in sacral pain preval ence. When the influence of serum relaxin concentration on back pain p revalence was taken into account, women carrying multiple pregnancies had no more pain than women carrying singletons, and IVF pregnant wome n had no more pain than spontaneously pregnant women. These results su pport the hypothesis that relaxin is involved in the generation of pel vic pain in pregnant women.