Assessment of fetal growth trajectory identifies infants at high risk of perinatal mortality.

Objective: To analyze perinatal risks associated with three distinct scenarios of fetal growth trajectory in the latter half of pregnancy compared with a reference group. Methods: This cohort study included women with a singleton pregnancy that delivered between 32 + 0 and 41 + 6 weeks' gestation and had two or more ultrasound scans, at least 4 weeks apart, from 18 + 0 weeks. We evaluated three different scenarios of fetal growth against a reference group, which comprised appropriate‐for‐gestational‐age fetuses with appropriate forward‐growth trajectory. The comparator growth trajectories were categorized as: Group 1, small‐for‐gestational‐age (SGA) fetuses (estimated fetal weight (EFW) or abdominal circumference (AC) persistently < 10th centile) with appropriate forward growth; Group 2, fetuses with decreased growth trajectory (decrease of ≥ 50 centiles) and EFW or AC ≥ 10th centile (i.e. non‐SGA) at their final ultrasound scan; and Group 3, fetuses with decreased growth trajectory and EFW or AC < 10th centile (i.e. SGA) at their final scan. The primary outcome was overall perinatal mortality (stillbirth or neonatal death). Secondary outcomes included stillbirth, delivery of a SGA infant, preterm birth, emergency Cesarean section for non‐reassuring fetal status and composite severe neonatal morbidity. Associations were analyzed using logistic regression. Results: The final study cohort comprised 5319 pregnancies. Compared to the reference group, the adjusted odds of perinatal mortality were increased significantly in Group 2 (adjusted odds ratio (aOR), 4.00 (95% CI, 1.36–11.22)) and Group 3 (aOR, 7.71 (95% CI, 2.39–24.91)). Only Group 3 had increased odds of stillbirth (aOR, 5.69 (95% CI, 1.55–20.93)). In contrast, infants in Group 1 did not have significantly increased odds of demise. The odds of a SGA infant at birth were increased in all three groups compared with the reference group, but was highest in Group 1 (aOR, 111.86 (95% CI, 62.58–199.95)) and Group 3 (aOR, 40.63 (95% CI, 29.01–56.92)). In both groups, more than 80% of infants were born SGA and nearly half had a birth weight < 3rd centile. Likewise, the odds of preterm birth were increased in all three groups compared with the reference group, being highest in Group 3, with an aOR of 4.27 (95% CI, 3.23–5.64). Lastly, the odds of composite severe neonatal morbidity were increased in Groups 1 and 3, whereas the odds of emergency Cesarean section for non‐reassuring fetal status were increased only in Group 3. Conclusion: Assessing the fetal growth trajectory in the latter half of pregnancy can help identify infants at increased risk of perinatal mortality and birth weight < 3rd centile for gestation. © 2024 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]