title: Comment on "On gestational weeks and maths".
authors.affiliation: Department of Obstetrics, Gynecology and Reproductive Medicine, Medical Center Alkmaar, Wilhelminalaan 12, 1815 JD, Alkmaar, the Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: Hummel
mesh_terms: D000782:Aneuploidy; D005260:Female; D006801:Humans; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*