[Vertex presentation in the morning--breech presentation at noon: a nursery tale? A prospective study of 1,019...

The percentage of breech presentations in the course of the 32nd to 40th week of gestation is 5.1%; vertex presentations were found in 94.9%. In the primiparae we found 6.0% of breech presentations against 4.3% in the multiparae. Sub partu there were breech presentations in 4.5% (in primiparae more often than in multiparae). A spontaneous change from vertex- into breech presentation from the 32nd to 40th week of gestation was evident in 4 cases = 0.41% [in the primiparae (n = 484) in one case = 0.21%; in the multiparae (n = 531) in 3 cases = 0.59%]. A change from breech presentation (n = 52) into vertex presentation occurred in the same period in 9 cases = 17.31% [in primiparae (n = 29) in 10.34%, in multiparae (n = 23) in 26.09%; the difference is statistically not significant!] All cases of change from vertex- into breech presentation were seen until the 35th week of pregnancy, not later, whereby the cases of change from breech- into vertex presentation happend until the 36th week of pregnancy (except one "late" change in the 39th week in a multipara), in the primiparae until the 36th week, in the multiparae until the 35th week of gestation. Thus, apart from rare exceptions, the definite birth-presentation of the fetus has taken place about the 35th/36th week of gestation. Late changes of position of the fetus are not likely. A diagram with the exact percentages and likelihood of changes of the fetus presentation for primi- and multiparae between 32nd and 40th week of gestation is given.