Strengths and Limitations
One major strength of this study is that the findings can be directly translated into everyday practice. Due to the adjustments we made to the original ESH-IP 2010, this study provides valuable information concerning the implications of the use of such a device in clinical practice. Along with research this study also has some potential methodological imperfections that need to be addressed. First, we did not perform a validation study following the strict criteria the ESH-IP 2010 protocol. Critics might say that the CDXP needs a validation before it can be used in daily practice. However, we showed that the margins of difference from the gold standard are comparable to the validated Omron M6 Comfort. Therefore, we think our data show that the CDXP is just as reliable. Second, it was necessary to adjust the blood pressure ranges of the ESH-IP 2010 to make it directly applicable on a pregnant population, as normal blood pressure ranges strongly differ from a non-pregnant population9. Third, we used one non-blinded observant taking all the measurements instead of two blinded observants as proposed by the ESH-IP 2010. However, as the observant measured the aneroid blood pressure before the device measurements we do not think this influenced our results. Fourth, in phase 1 and 2 we used different reference devices (Omron M6 Comfort and Welch Allyn 5300P) to compare to the CDXP. Although both reference devices have been validated in pregnancy, this theoretically might have induced small differences between the two phases. However, we do not think this to be clinically relevant. We think the CDXP can be used for HBPM during pregnancy.