This study is designed to predict implantation of a fresh, high quality embryo in an in vitro fertilization (IVF) cycle by using ultrasound based uterine factors.

Investigators will recruit patients <40 years with no background morbidities who are being treated with IVF or IVF intra cytoplasmic sperm injection (ICSI) for acceptable indications. Only patients reaching a blastocyst transfer will be recruited ; this criterion will assist in minimizing embryonal quality as a factor in the implantation chance. The investigators will limit the quality to good quality embryos, which in the unit's routine practice are transferred in a single embryo transfer. On Day 5, embryos will be scored for blastocyst formation. Blastocysts will be graded according to the size of the blastocyst, the assessment of the inner cell mass (ICM) and trophectoderm development as suggested by Gardner. Good quality embryos (Grade 1-2) will be defined as those where at least: "3" score if the cavity completely fills the embryo, "B" when the ICM is loosely grouped with several cells and "B" when the trophectoderm has very few cells forming a loose epithelium. Lower criteria embryos on Day 5 will be defined as poor quality embryos (Grade 3 or 4). Blastocyst grading will be performed by two trained embryologists, each with over 10 years of experience. The study will not involve any change in the conventional IVF treatment; the only change will involve a 3D trans-vaginal ultrasound at the morning of the embryo transfer, before patients are initiating bladder filling (a common request from all abdominally assisted embryo transfers, facilitating an easier pathway to the uterus and an excellent view). The estimated time for the ultrasound test is 5-8 minutes and will include recording of the following variables : endometrial thickness, endometrial pattern, endometrial -myometrial junction appearance, subendometrial wave contractions (presence and number), endometrial surface area. The information will be recoded under the patients' unique study identity number and will be stored in a special computerized archived file secured by Meir medical center data protection and computer unit. The data will not affect any treatment decisions in the IVF unit unless this examination will reveal for the first time the presence of an unknown uterine polyp or the presence of a hydrosalpinx. Such scenario is improbable since in the performing unit, patients are routinely going through a uterine cavity assessment and a pelvic ultrasound scan prior to an IVF cycle. If this indeed happens then the ultrasound unit will contact the IVF unit and the treating physician will discuss the data with the patient in order to decide whether to go on with the transfer or to freeze the embryo/s until treating the new findings. Upon completion of 150 patients/studies, the ultrasound file will be analyzed by two highly trained and experienced examiners. Each of the variables collected will be used in a multivariate model for implantation incorporating the patient's age.

Inclusion Criteria:

• Single day 5 fresh embryo transfer of good quality
• Age<40

Exclusion Criteria:

• Frozen embryo transfer
• Age>40
• Day 2-3 transfer
• Double embryo transfer