title: Down syndrome is not increased in offspring of natural family planning users (case control analysis)
authors.forename: E E
authors.initials: EE
authors.lastname: Castilla
authors.forename: J L
authors.initials: JL
authors.lastname: Simpson
authors.forename: J T
authors.initials: JT
authors.lastname: Queenan
mesh_terms: D016022:Case-Control Studies; D003267:Contraception / Q000009:adverse effects; D004314:Down Syndrome / Q000209:etiology*; D005193:Family Planning Services; D005260:Female; D006801:Humans; D008297:Male