Cephalopelvic Disproportion: A condition in which the HEAD of the FETUS is larger than the mother's PELVIS through which the fetal head must pass during a vaginal delivery.Pelvimetry: Measurement of the dimensions and capacity of the pelvis. It includes cephalopelvimetry (measurement of fetal head size in relation to maternal pelvic capacity), a prognostic guide to the management of LABOR, OBSTETRIC associated with disproportion.Vacuum Extraction, Obstetrical: Removal of the fetus from the uterus or vagina at or near the end of pregnancy with a metal traction cup that is attached to the fetus' head. Negative pressure is applied and traction is made on a chain passed through the suction tube. (From Stedman, 26th ed & Dorland, 28th ed)Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Myopathies, Structural, Congenital: A heterogeneous group of diseases characterized by the early onset of hypotonia, developmental delay of motor skills, non-progressive weakness. Each of these disorders is associated with a specific histologic muscle fiber abnormality.Muscle Hypotonia: A diminution of the skeletal muscle tone marked by a diminished resistance to passive stretching.