validity of these data may be affected by patient-reported biases, small subject numbers, and other confounding variables. Ovarian hyperstimulation syndrome Estrogen antagonists and gonadotropins may stimulate multiple follicles and other ovarian hormones leading to multiple birth and possible ovarian hyperstimulation syndrome (OHSS). Development of OHSS is dependent on the administration of hCG and is mediated through vascular endothelial growth factor (VEGF). OHSS is characterized as cystic enlargement of the ovaries. Multiple birth is especially deleterious due to compounding risks including premature delivery and low birthweight, pre-eclampisa, and increased risk of neonatal mortality. While triplet births have been declining in ART, multiple births remain over 50% of births from IVF. However, there are limitations to measure, as 4% to 8% IVF clinics to do not report their data to the CDC. Discontinuation Main reasons for discontinuation across all types of fertility treatment and treatment stage, are "postponement of treatment, physical and psychological burden and relational and personal problems". See also Assisted reproductive technology Diethylstilbestrol References