In a case control study of 81 twin gestation where 36 were induced with oxytocin, prostaglandins or laminaria tents and 45 others delivered without induction, the duration of labor in the two groups were similar (6.5 บวกลบ 2.8 hrs vs 6บวกลบ 3.6 hrs. )[36]. We found a difference in the duration of labor in the two groups, 6 hrs in the group that was induced, a difference of 3.75 hrs (P