A study found that pregnancies in which the uterus undergoes hormone therapy before frozen embryo transfer have a higher rate of hospitalization for vascular problems. Dr Sylvie Epelboin from the Hôpital Bichat-Claude Bernard in Paris, France presented the research which was carried out on behalf of the French Biomedicine Agency. This is the first large-scale study to examine the relationship between endometrial preparation method and high blood pressure during pregnancy. Other studies have shown that the incidence of preeclampsia is higher in pregnancies resulting from frozen embryo transfer compared with fresh embryo transfer or natural conception. It is therefore recommended that ovulatory cycle frozen embryo transfer be preferred as a first-line protocol where possible.