Hello there. The most immediate possible effect is that acupuncture served to “relax” the uterus around the time of the transfer. Several studies have shown that the uterus has contractions and that these contractions could cause expulsion of the transferred IVF embryos. If the contractions were reduced by acupuncture then that could be a mechanism for an improvement in IVF pregnancy rate. Many patients have been told that they should use acupuncture for IVF because they will respond better to medication.