THE VALUE OF MATERNAL HEIGHT AS A RISK FACTOR OF DYSTOCIA - A METAANALYSIS

Ten publications and studies on the relation between maternal height a nd the risk of dystocia due to cephalopelvic disproportion (CPD) are a nalysed. The rate of Caesarean sections was chosen as the CPD indicato r. When maternal height is presented in percentiles, curves can be sup erimposed, and sensitivities and specificities of the various studies may be analysed together. One biased study was excluded; the remaining 9 were pooled and regression lines calculated for sensitivity (Se) an d specificity (Sp) of the entire set of points. The resulting model, i .e. Se=10.9+1.99 Y and Sp=99.9 - 0.99 Y, permits easy calculation of t he expected sensitivity and specificity for each percentile Y. When th e frequency of Caesarean section due to CPD is known, positive and neg ative predictive values can also be calculated. The proposed formulas can also be used to determine confidence intervals. The findings in te rms of the sensitivity and specificity of low maternal height as a ris k factor for dystocia indicate that I out of 5 pregnant women would ha ve to be referred for further investigation to identify half of the ca ses of mechanical dystocia necessitating Caesarean section. The predic tive value for a Caesarean rate of 2% (a value often seen in developin g countries) for this 20th percentile would be only 5%. Practical ways of choosing a reference criterion are suggested. A two-track strategy (antenatal check-ups and community monitoring) is proposed.