Reproductive technology: Reproductive technology (RT) encompasses all current and anticipated uses of technology in human and animal reproduction, including assisted reproductive technology, contraception and others.Male infertilityNatural cycle in vitro fertilization: Natural Cycle IVF is in vitro fertilisation (IVF) using either of the following procedures:Prenatal nutrition: Nutrition and weight management before and during :pregnancy has a profound effect on the development of infants. This is a rather critical time for healthy fetal development as infants rely heavily on maternal stores and nutrient for optimal growth and health outcome later in life.Pregnancy rate: Pregnancy rate is the success rate for getting pregnant. It is the percentage of all attempts that leads to pregnancy, with attempts generally referring to menstrual cycles where insemination or any artificial equivalent is used, which may be simple artificial insemination (AI) or AI with additional in vitro fertilization.Embryo transfer: Embryo transfer refers to a step in the process of assisted reproduction in which embryos are placed into the uterus of a female with the intent to establish a pregnancy. This technique (which is often used in connection with in vitro fertilization (IVF)), may be used in humans or in animals, in which situations the goals may vary.AzoospermiaSelective reduction: Selective reduction (or multifetal pregnancy reduction or MFPR) is the practice of reducing the number of fetuses in a multifetal pregnancy, say quadruplets, to a twin or singleton pregnancy.Spermiogenesis: Spermiogenesis is the final stage of spermatogenesis, which sees the maturation of spermatids into mature, motile spermatozoa. The spermatid is more or less circular cell containing a nucleus, Golgi apparatus, centriole and mitochondria.Twin reversed arterial perfusionOvarian hyperstimulationOvarian tissue cryopreservation: Ovarian tissue cryopreservation is cryopreservation of tissue of the ovary of a female.Hyperactivation: Hyperactivation is a type of sperm motility. Hyperactivated sperm motility is characterised by a high amplitude, asymmetrical beating pattern of the sperm tail (flagellum).Semen quality: Semen quality is a measure of the ability of semen to accomplish fertilization. Thus, it is a measure of fertility in a man.Sperm: Sperm is the male reproductive cell and is derived from the Greek word (σπέρμα) sperma (meaning "seed"). In the types of sexual reproduction known as anisogamy and its subtype oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell.Unexplained infertility: Unexplained infertility is infertility that is idiopathic in the sense that its cause remains unknown even after an infertility work-up, usually including semen analysis in the man and assessment of ovulation and fallopian tubes in the woman.merckmanuals > Unexplained Infertility Last full review/revision November 2008 by Robert W.Oocyte selection: Oocyte selection is a procedure that is performed prior to in vitro fertilization, in order to use oocytes with maximal chances of resulting in pregnancy. In contrast, embryo selection takes place after fertilization.