LEXINGTON, Ky. &ndash; Rachel Alexandra, the 2009 Horse of the Year, is in foal to two-time Horse of the Year Curlin. Stonestreet Stables, owner of both the mare and the stallion, announced the pregnancy Monday.\r\nThe mating of the two Horses of the Year was the first for 5-year-old Rachel Alexandra. The Medaglia d&rsquo;Oro mare was bred on Feb. 21, 2011. The horse&rsquo;s gestation period is 11 months, and Rachel Alexandra&rsquo;s estimated foaling date is Feb. 1, 2012.\r\nCurlin, 7, stands this year for $40,000 at Lane&rsquo;s End Farm in Versailles, Ky., where the breeding took place.\r\nThe reigning Horse of the Year, 7-year-old Zenyatta, also was bred for the first time last month. That mating with Darley Stud&rsquo;s champion 3-year-old Bernardini took place on Feb. 23 at Sheikh Mohammed al-Maktoum&rsquo;s Jonabell Farm facility in Lexington. Owners Ann and Jerry Moss board Zenyatta at Lane&rsquo;s End. Equine pregnancies usually are confirmed by ultrasound between 12 and 16 days post-breeding, and Zenyatta&rsquo;s pregnancy status could be confirmed as early as this week.\r\nRachel Alexandra was Horse of the Year and champion 3-year-old filly in 2009 after winning the Preakness Stakes, the Kentucky Oaks, the Haskell, the Mother Goose, and the Woodward that season. In her three-season racing career, Rachel Alexandra won 11 stakes, nine of the them graded, and earned more than $3.5 million. She raced first for breeder Dolphus C. Morrison and then for the partnership of Stonestreet Stables and Harold McCormick.\r\nZenyatta, a daughter of Street Cry bred by Eric Kronfeld, was champion older female in 2008-2010. Racing from ages 3 to 6, she won the 2009 Breeders&rsquo; Cup Classic and a dozen other Grade 1 races. She retired with more than $7.3 million in earnings after finishing second to Blame in the 2010 Breeders&rsquo; Cup Classic.