Fetal front-abdominal wall thickness in the second trimester as a predictor of abnormal fetal growth

Objectives: Worldwide, approximately 9% of infants have a birth weight >= 4000 g, who are defined as fetal macrosomia, with wide variations between countries. Another form of abnormal fetal growth is fetal growth restriction. Infants with low birth weight (LBW) for their gestational age are primarily categorized as either small for gestational age (SGA) or fetal (intrauterine) growth restriction (FGR). All forms of abnormal fetal growth have high morbidity rates of neonatal. Therefore, diagnosis of abnormal fetal growth as early as possible is crucial for optimal clinical care. The measurement of fetal front-abdominal wall thickness (FAWT) is an easy examination. We conducted this study, wondering whether FAWT can predict birth weight or can determine LGA/macrosomia and/or LBW infants in advance. Methods: This longitudinal cohort study was done in a tertiary center between September 2016 and September 2019. In total, 768 pregnant women with who attended our clinic for oral glucose tolerance test (OGTT) screening between the 26th and 28th weeks of gestation were included in this study. A total of 768 patients were evaluated in the present study. However, 186 of them were excluded in the follow-up of the study because they met the exclusion criteria or they gave birth in another hospital. Eventually, 582 pregnant women were included, with 57 in the LBW group, 461 in the AGA group, and 64 in the LGA group. In addition, 55 fetuses in the LGA group were determined to be macrosomic (birth weight > 4000 g). The FAWT and classic fetal biometric measurements, such as BPD, AC, FL, and EFW, were compared between the AGA group and the macrosomic infants. Statistical analysis was performed to compare the AGA group and the macrosomic infants group. There were no macrosomic infants in the AGA group, so this was used as the control group. Results: There were no significant differences between the groups for maternal age, gravidity, parity, gestational age on the day of the examination, and gestational age at birth. The mean FAWT was significantly thinner in the SGA group than in the appropriate for gestational age (AGA) group (3.4 versus 3.9 mm, respectively, p < .001), while it was significantly thicker in the LGA group than in the AGA group (4.1 versus 3.9 mm, respectively, p < .001). Conclusion: FAWT measurement can provide more information and may be more sensitive toward fetal nutrition and growth than the AC value during the second trimester. Some benefits can be gained through the measurement of FAWT at the end of the second trimester. FAWT measurements can be used in obstetrical practice with a similar performance in predicting the LGA and macrosomic infant like AC and EFW