Validity of Maternal Report of Birthweight in a Cohort Study and Its Implication on Low Birthweight Rate Using Simulations

ABSTRACT

Objective:Maternal recall of birthweight is a convenient and cost-effective way to obtainbirthweight measurements when official records are unavailable. It is important to assess thevalidity of maternal recall of birthweight before using these measurements to drawconclusions about a population. Methods:This is secondary analysis of data from a previouscohort study.We analyzed actual and reported birthweights of 200 mother-and-child pairsfrom Southern India. We validated maternal report of birthweight by generating correlationcoefficients, summary statistics, and Bland-Altman plots. We ran simulations to evaluatehow misclassification as low or normal birthweight changed with the mean birthweight of thecohort. Results:Reported birthweight was strongly correlated with actual birthweight(r=0.80, P<0.001); 55%, 78.5%, and 93% of subjects reported values within 50 g, 250 g, and500 g, respectively of actual birthweight. None of sociodemographic covariates wassignificantly associated with the accuracy of maternal recall of birthweight. 7.5% of childrenwere misclassified as either low or normal birthweight by reported birthweight. Simulationsrevealed that increasing the reported and actual birthweights by 500g reduces themisclassification rate from 7.5% to 1.5%. Conclusion:Maternal recall is a sufficientlyaccurate measure of actual birthweight. However, the distribution of actual birthweight in thepopulation must be taken into consideration when classifying babies as low or normalbirthweight, especially in populations where mean birthweight is close to 2500g