Fetal size and growth velocity in chronic hypertension

Objective To investigate longitudinal fetal growth and growth velocity for commonly measured biometric parameters in women with chronic hypertension. Methods Two centre retrospective European study of women with chronic hypertension ascertained at pregnancy booking. Ultrasound measurements of head circumference (HC), abdominal circumference (AC) and femur length (FL) were used to derive longitudinal fetal growth charts derived using functional linear discriminant analysis (FLDA). These were compared to existing cross sectional and longitudinal charts, as was birthweight. Results 282 women with a median of 3 third trimester ultrasound examinations were included. Gestation at delivery was 37.5 weeks (SD 2.68), birthweight 3049 g (SD 785). Birthweight <10th percentile found in 15.6% deliveries, >90th percentile 20.2%. Fetal size curves derived from women with chronic hypertension were no different to cross sectional and longitudinal charts for a normal population. Compared to a standard longitudinal biometry chart, growth velocity (mm/day) in chronic hypertension was higher for AC and FL at 30–32 weeks (AC 1.447 vs 1.357 p < 0.05; FL 0.296 vs 0.269 p < 0.01) and 34–36 weeks (AC 1.325 vs 1.140 p < 0.01; FL 0.248 vs 0.198 p < 0.01). Conclusions In women with chronic hypertension there is an excess of both SGA and LGA babies compared to population standards. Growth velocity of the AC and FL was greater after 30 weeks compared to a normal population.