The WHO Alliance for Maternal and Newborn Health Improvement Late Pregnancy Dating Study Group, et al. - The accuracy of the ultrasound scan in estimating gestational age in late pregnancy (ie, after 24 weeks' gestation) in low-income and middle-income countries (LMICs) is evaluated and improved; in these regions, access to ultrasound in the first half of pregnancy is rare and where intrauterine growth restriction is prevalent. They performed estimation of gestational age by standard fetal biometry measurements in addition to transcerebellar diameter (TCD) measurements vs gold-standard crown-rump length (CRL) measurements by using Bland-Altman plots to determine the mean difference and 95% limits of agreement. New gestational age prediction formulas were developed for third trimester ultrasonography via performing statistical modelling. In this study, they enrolled 1,947 women carrying a live singleton fetus dated by CRL measurements between 8⁺⁰–14⁺⁶ weeks of gestation, who were willing to return for two additional ultrasound scans, and who planned on delivering in the study area. One thousand three hundred eighty-seven pregnant women underwent an ultrasound scan at 24⁺⁰–29⁺⁶ weeks of gestation and 1,403 underwent an ultrasound scan between 30⁺⁰–36⁺⁶ weeks of gestation. Late pregnancy ultrasound at 24⁺⁰–29⁺⁶weeks' gestation was accurate to within about plus or minus 2 weeks of the gold-standard CRL measurement of gestational age, and late pregnancy ultrasound was accurate to within ±3 weeks of the CRL measurement at 30⁺⁰–36⁺⁶ weeks' gestation when it was used with standard dating formulas. The outcomes suggest that an improvement in the the accuracy of gestational age estimation in both appropriate-for-gestational-age and small-for-gestational-age infants in LMICs could be achieved with incorporation of TCD and the use of new formulas in late pregnancy ultrasound scans. These results might be especially relevant in LMICs in view of the high rates of small-for-gestational-age infants.