title: Letter: Seasonal variation of patent ductus arteriosus.
mesh_terms: D004374:Ductus Arteriosus, Patent / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious; D012409:Rubella / Q000150:complications; D012621:Seasons; D012737:Sex Factors