Centile calculator for MAP at 11-13 weeks
The data were derived from the study of 13,946 singleton pregnancies with a live fetus at 11+0 - 13+6 weeks and no major defects or chromosomal abnormalities.
Measurement of MAP is useful in the prediction of risk for subsequent development of preeclampsia. The MAP is considered to be increased if it is above the 90th centile. Accurate assessment of risk for preeclampsia is provided by a combination of maternal characteristics, MAP, uterine artery PI and maternal serum biochemistry (see the preeclampsia calculator)
In normal pregnancy MAP increases with maternal weight. In assessing whether a measurement is normal or not maternal characteristics should be taken into consideration.
Measurement of MAP
The blood pressure should be taken with automated devices (3BTO-A2, Microlife, Taipei, Taiwan) which are calibrated at regular intervals. The women should sit in a chair without their legs being crossed and with their arms supported at the level of the heart. An appropriate cuff size should be selected depending on the mid-arm circumference (small <22 cm, normal 22-32 cm, or large 33-42 cm). The blood pressure should be measured in both arms simultaneously, series of recordings at 1-min intervals should be taken until they become stable (in the last two recordings the difference in systolic blood pressure should be less than 10 mmHg and the difference in diastolic blood pressure should be less than 6 mmHg). The MAP of each arm should be calculated as the average of the last two stable measurements and the measurement from the arm with the highest final pressure should be used.
It is strongly recommended that those undertaking assessment of risk receive the Fetal Medicine Foundation Certificate of competence in Doppler ultrasound ( FMF Certificates of Competence)
Please record the following information and then press Calculate.
Please record the last two measurements. If your machine records the value of MAP then enter this otherwise enter the measurements of systolic and diastolic blood pressure and the calculator will estimate the MAP.
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