Running through the fields with her newly-born foals, mare Royal Beatrice has good reason to celebrate - after managing the astonishingly rare feat of producing twins. The 22-year-old New Forest Pony has shocked equine experts with the surprise birth of healthy twin foals because the chances of both surviving are so slim. In nearly all cases, one or both foals die in a twin pregnancy because the mother's uterus cannot support two babies. The chances of a mare giving birth to healthy twin foals are about 1 in 10,000, experts said today. But little filly Bess, and colt Royal, have defied the odds by becoming the first twins to be born in the New Forest, Hampshire for many years.