After the point of fertilization, the fused product of the female and male gamete is referred to as a zygote or fertilized egg. The fusion of female and male gametes usually occurs following the act of sexual intercourse. Pregnancy rates for sexual intercourse are highest during the menstrual cycle time from some 5 days before until 1 to 2 days after ovulation. Fertilization can also occur by assisted reproductive technology such as artificial insemination and in vitro fertilisation. Fertilization (conception) is sometimes used as the initiation of pregnancy, with the derived age being termed fertilization age. Fertilization usually occurs about two weeks before the next expected menstrual period. A third point in time is also considered by some people to be the true beginning of a pregnancy: This is time of implantation, when the future fetus attaches to the lining of the uterus. This is about a week to ten days after fertilization. Development of embryo and fetus
The sperm and the egg cell, which has been released from one of the females two ovaries, unite in one of the two Fallopian tubes. The fertilized egg, known as a zygote, then moves toward the uterus, a journey that can take up to a week to complete. Cell division begins approximately 24 to 36 hours after the female and male cells unite. Cell division continues at a rapid rate and the cells then develop into what is known as a blastocyst. The blastocyst arrives at the uterus and attaches to the uterine wall, a process known as implantation.
Renal hypoplasia is an abnormality that a person is born with in which one or both of the kidneys are smaller than normal (hypoplastic) but with normal structure.It is defined as abnormally small kidneys, where the size is less than two standard deviations below the expected mean for the corresponding demographics, and the morphology is normal. Disease severity depends on whether hypoplasia is unilateral or bilateral, and the degree of reduction in the number of nephrons. Presentation
Hypoplastic kidneys are prone to infection and kidney stone formation, have a reduced nephron number,( normal corticomedullary differentiation)

Complications
Renal hypoplasia is a common cause of kidney failure in children and also of adult-onset disease. Diagnosis
Diagnosis is typically through ultrasonography. Prevalence
Epidemiologic studies point to an estimated incidence of 1 in 400 births. == References ==