Background: In modified natural cycle IVF (MNC-IVF), treatment is aimed at using the one follicle that spontaneously develops to dominance, using a GnRH-antagonist together with gonadotrophins in the late follicular phase only. The MNC-IVF is of interest because of its low-risk and patient-friendly profile. The effect of application of MNC-IVF preceding standard IVF with ovarian stimulation on overall results is unknown.
Methods: This single-center cohort study provides follow-up of an earlier study in which nine cycles of MNC-IVF were offered to 268 patients. Ongoing pregnancy rates and live birth rates, as well as time-to-pregnancy after controlled ovarian stimulation-IVF (COS-IVF) following MNC-IVF, were evaluated.
Results: Actual observed cumulative ongoing pregnancy rates and live birth rates after sequential treatment with MNC-IVF followed by COS-IVF were 51.5 (95% CI: 45.4-57.6) and 50.0% (95% CI: 43.9-56.1) per patient, of which 8.0 and 6.7% were twins. Median time to ongoing pregnancy was 28.8 weeks. Including treatment-independent pregnancies, cumulative ongoing pregnancy rate was 56.7% (95% CI: 50.7-62.8).
Conclusions: Sequential treatment with MNC-IVF followed by COS-IVF does not appear to compromise overall success rates, while twin pregnancy rate is low. Because of its patient-friendly and low-risk profile, it seems appropriate to perform MNC-IVF preceding COS-IVF.