Browsing by Author "Saarinen, Ilona"

The aim of this retrospective case-control study was to investigate association between post-term pregnancy and ABO blood groups and Rhesus factor. The original data was derived from the Helsinki University Central Hospital over a 4-year period (n=58,036 deliveries). The data on ABO blood groups and Rhesus factors were collected from Weblab-database and combined with the original data. There were 378 cases (post-term) and 8,626 controls (gestational age 37+0 – 41+6) after data linkage. Statistical comparisons were performed using Chi-Square and Mann-Whitney U-tests. The association between blood groups and the length of the pregnancy was analyzed by binary unconditional logistic regression. The AB blood group, and especially AB+ blood group, was associated with 1.5- and 1.6-fold higher risk of post term pregnancy, respectively. The Rhesus factor was not associated with higher or lower risk. Thus, gravidas without anti-A, anti-B and anti-D antibodies seem to have the highest risk for postterm pregnancy.