Fetal growth velocity references from a Chinese population-based fetal growth study

Fetal growth velocity standards have yet to be established for the Chinese population. This study aimed to establish such standards suitable for the Chinese population.

We performed a multicenter, population-based longitudinal cohort study including 9075 low-risk singleton pregnant women. Data were collected from the clinical records of 24 hospitals in 18 provinces of China. Demographic characteristics, reproductive history, fetal ultrasound measurements, and perinatal outcome data were collected. The fetal ultrasound measurements included biparietal diameter (BPD), abdominal circumference (AC), head circumference (HC), and femur diaphysis length (FDL). We used linear mixed models with cubic splines to model the trajectory of four ultrasound parameters and estimate fetal weight. Fetal growth velocity was determined by calculating the first derivative of fetal size curves. We also used logistic regression to estimate the association between fetal growth velocities in the bottom 10th percentile and adverse perinatal outcomes.

Fetal growth velocity was not consistent over time or among individuals. The estimated fetal weight (EFW) steadily increased beginning at 12 gestational weeks and peaked at 35 gestational weeks. The maximum velocity was 211.71 g/week, and there was a steady decrease in velocity from 35 to 40 gestational weeks. The four ultrasound measurements increased in the early second trimester; BPD and HC peaked at 13 gestational weeks, AC at 14 gestational weeks, and FDL at 15 gestational weeks. BPD and HC also increased from 19 to 24 and 19 to 21 gestational weeks, respectively. EFW velocity in the bottom 10th percentile indicated higher risks of neonatal complications (odds ratio [OR] = 2.23, 95% confidence interval [CI]: 1.79-2.78) and preterm birth < 37 weeks (OR = 3.68, 95% CI: 2.64-5.14). Sensitivity analyses showed that EFW velocity in the bottom 10th percentile was significantly associated with more adverse pregnancy outcomes for appropriate-for-gestational age neonates.

We established fetal growth velocity curves for the Chinese population based on real-world clinical data. Our findings demonstrated that Chinese fetal growth patterns are somewhat different from those of other populations. Fetal growth velocity could provide more information to understand the risk of adverse perinatal outcomes, especially for appropriate-for-gestational age neonates.