Prevalence and Risk Factors of Term Singleton Fetal Macrosomia: A Multicenter Case-Control Study

Abstract

Background and Objective: Fetal macrosomia increases the complications that some is life threatening. The cut-off birthweight at over 4,000 gram is commonly used for its diagnosis, however the clinical definition of cut-off value of fetal macrosomia is still debatable and needs more knowledge to determine. This study aimed to study the prevalence, risk factors, outcomes and optimal cut-off value of term singleton high birthweight infants in Thailand.

Methods: A multicenter case - control study was conducted. The subjects were term singleton pregnant women who delivered in Kumphawapi, Udonthani, Nong Han, Ban Phue, Wanonniwat, Ban Dung, Lom Sak, and Ang Thong Hospital between 1 January, 2018 to 31 December, 2023. Data was collected from the hospital’s database and then analyzed using descriptive statistics and multiple logistic regression analysis.

Results:  There were 43,129 term singleton infants with 927 term macrosomic (≥ 4,000 grams) infants (2.15%). The risk factors of fetal macrosomia were obese (AOR 2.89, 95%CI 2.16-3.85), diabetes mellitus (AOR 2.90, 95%CI 2.31-3.64), overweight (AOR 2.21, 95%CI 1.74-2.80), excessive gestational weight gain (AOR 1.91, 95%CI 1.54-2.37), multiparity (AOR 1.73, 95%CI 1.39-2.16). Fetal macrosomia increased the risk of shoulder dystocia (AOR 41.17, 95%CI 10.18-166.42), primary cesarean delivery (AOR 3.01, 95%CI 2.47-3.68), and postpartum hemorrhage (AOR 2.81, 95%CI 1.40-5.64). The mean birthweight of term singleton infants was 3,036.59± 498.42 g. The 90^th percentile was 3,610 grams that correlated with the composite complication, primary cesarean delivery and postpartum hemorrhage were increased significantly when the birthweight was more than or equal to 3,600 grams when each 100 grams increment of birthweight was analyzed.

Conclusion: On the basis of the 4,000 grams traditional cut-off point, the prevalence of fetal macrosomia was found to be 2.15%. The risk factors of fetal macrosomia were maternal obesity, diabetes mellitus, overweight, and multiparity. However, the new cut-off birthweight at 3,600 grams (90^th percentile) for the determination of high birthweight is suggested from this study’s evidence that the risk of shoulder dystocia, primary cesarean delivery, and postpartum hemorrhage were increased significantly in the higher birthweight than this cut-off point. Pregnant women with risk factors who have estimated fetal weight more than or equal to this cut-point should be closely monitored or referred to the higher facility hospital for caring these complications.