1. An elderly obstetrical patient;Gilbertson;Br Med J,1917
2. Pregnancy after fifty;Natter;Obstet Gynecol,1964
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4. Pregnancy in women over forty;Horger;Obstet Gynecol,1977
5. Pregnancy in the older gravida: how old is old?;Hollander;Obstet Gynecol Surv,1990