Comparative Study of Two Clinical Methods of Estimating Foetal Weight in Two Hospitals in Bamenda Health District-A Prospective Study.

CaHReF 2016,Yaoundé Conges hall, 23 – 26 August 2016 , PL010

The weight of a foetus is an important predictor of perinatal mortality, morbidity and maternal morbidity. Clinical and sonographic methods exist for estimating foetal weight. Sonographic equipment is costly, requires specially trained personnel and may not be available in low resource settings in Cameroon. We compared two clinical methods based on symphysio-fundal height measurements which are used in low resource settings in Cameroon, namely the Johnson’s and Kornyuy-Mbu’s formulae. Accurate estimation of foetal weight will help in determining the optimal route of deliveryand improve neonatal management.

This study was aimed at determining the accuracy of Johnson’s and Kornyuy-Mbu’s methods in estimating foetal weight, and to find out the most accurate method within the birth weight categories.

This was a cross sectional study where 206 consented parturients with singleton pregnancies were sampled consecutively at the maternity of Regional Hospital Bamenda and Medicalised Health Centre Nkwen from December 1st, 2015 to February 26th, 2016. We measured the fundal heights and applied the Kornyuy-Mbu’s formula for estimating foetal weight and compared with Johnson’s estimations and actual birth weights. Accuracy was determined in terms of percentage error between estimated and actual birth weights and by the proportion of estimates within 10% of the actual birth weights.

The average birth weight was 3351±402g. The mean gestational was 39.8±0.9 weeks. One baby (0.45%) weighed <2500g, 89.3% weighed between 2500-<4000 and 10.19% had weights ≥4000g.The overall accuracy within 10% of actual birth weight was 61% and 57% for the Johnson's and Kornyuy-Mbu's formula respectively.The Kornyuy-Mbu’s method overestimated birth weights in all categories while Johnson’s underestimated birth weights in the third category with a significant difference (p=0.012). There was a significant difference between the overall accuracy of both methods within 10% of actual birth weight. For non-obese participants, Kornyuy-Mbu’s formula was more accurate than Johnson’s formula (p<0.001).

Johnson's formula was more accurate than the Kornyuy-Mbu's formula.Both methods were inaccurate in the category <2500g. The Johnson's formula was more accurate in all birth weights>2500g.The Kornyuy-Mbu’s estimations were more accurate in estimating foetal weight than Johnson’s method in non-obese participants.

Clinical methods; Foetal weight estimation, Kornyuy-Mbu, Johnson; Accuracy.