title: Multiple gestation as a marker of reproductive efficacy: learning from assisted reproductive technologies.
abstract: This study postulates that apart from the number of embryos transferred, women with multiple gestation represent a subgroup of highly fertile individuals, whose embryos implant with higher efficiency than women with single gestation. Furthermore, each embryo generated from these women has a higher chance of reaching full term. The objective of this study was to compare implantation rate with the outcome of pregnancy (up to week 20) in multiple gestations following assisted reproductive techniques. The study group comprised 162 women with multiple gestation after assisted reproduction, followed prospectively with at least three ultrasound examinations performed between weeks 5 and 20 after the last menstrual period. Control group A comprised 344 fertile women with spontaneous single pregnancy followed with transvaginal ultrasound. Control group B consisted of 317 infertile women conceiving with single gestation after assisted reproduction and followed prospectively as in the study group. Embryo implantation rate and spontaneous embryo/fetal reduction, either partial or total (abortion), were registered in each case. Overall implantation in women with multiple gestation was higher (54.6%) than in the corresponding controls (25.6%). Furthermore, spontaneous embryo/fetus reduction was similar in the study cases and in fertile women (12.6 and 10.8% respectively) and significantly smaller than in the control group B (20.8%). Women with high reproductive efficacy exposed to assisted reproductive techniques generate cohorts of good quality embryos, with a high chance of implantation and of reaching birth.
authors.affiliation: Unit of Reproductive Medicine, Clínica Las Condes Lo Fontecilla 441, Las Condes, Santiago, Chile. umrdocencia@clinicalascondes.cl
authors.forename: F
authors.initials: F
authors.lastname: Zegers-Hochschild
authors.forename: M
authors.initials: M
authors.lastname: Bravo
authors.forename: E
authors.initials: E
authors.lastname: Fernández
authors.forename: C
authors.initials: C
authors.lastname: Fabres
authors.forename: J P
authors.initials: JP
authors.lastname: Balmaceda
authors.forename: A
authors.initials: A
authors.lastname: Mackenna
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology; D000328:Adult; D020732:Cytogenetic Analysis; D010064:Embryo Implantation; D005260:Female; D005298:Fertility; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D011272:Pregnancy, Multiple; D027724:Reproductive Techniques, Assisted; D013997:Time Factors