title: The relationship of IUD dimensions to event rates.
abstract: The relationship of horizontal-to-vertical ratio (HVR) of 14 commonly used IUDs was compared to medical removal and expulsion rates.  A significant positive statistical correlation between IUD HVR and medical removal rate existed.  However, no correlation existed between HVR and expulsion.  A ratio of about 0.5 for multiparous and 0.7 for nulliparous women less frequently in medical removal of the device.  The endometrial cavity length sizes have boundary values on IUD width of 15-18 mm for nulliparae and 18-25 mm for multiparae.  The endometrial cavity is thus functionally an isosceles triangle or isosceles trapezoid.
mesh_terms: D001723:Birth Rate; D003267:Contraception; D003710:Demography; D003933:Diagnosis; D005069:Evaluation Studies as Topic; D005193:Family Planning Services; D005298:Fertility; D007434:Intrauterine Devices; D007435:Intrauterine Devices, Copper; D007436:Intrauterine Devices, Medicated; D010298:Parity; D011153:Population; D011157:Population Dynamics
keywords: Contraception; Contraception Termination; Contraceptive Effectiveness; Contraceptive Methods; Demographic Factors; Examinations And Diagnoses; Family Planning; Fertility; Fertility Measurements; Iud; Iud, Copper Releasing; Iud, Hormone Releasing; Iud, Unmedicated; Multiparity; Nulliparity; Parity; Population; Population Dynamics; Size; Use-effectiveness