Clinical assessment of gestational age: a comparison of two methods.

The ratio of fundal height (FH) to maternal abdominal length (MAL) was defined as percentage of maternal abdominal length (PMAL) and compared to FH alone in 100 consecutive uncomplicated pregnancies from the 18th week of gestation to delivery at term. Reference graphs for fetal growth evaluation were developed using these two clinical methods. The predictive value of each technique was assessed by comparing gestational age estimates in 29 additional patients at various gestational ages. The correlation coefficient between the known gestational ages and estimates by the PMAL method was .86, and between known gestational ages and estimates by the FH method, .94. Twenty more patients were evaluated by three obstetricians in a double-blind fashion to determine gestational ages by each technique. The average deviation from the real gestational age varied from 2.07 to 3.14 weeks using the FH method, and from 2.82 to 3.97 weeks using the PMAL graph. It was concluded that FH measurement correlates better with gestational age than its ratio to the MAL.