The extremely large fetus--antenatal identification, risks, and proposed management

Area of Science:

• Obstetrics and Gynecology
• Perinatal Medicine
• Neonatal Outcomes

Background:

• Accurate identification of fetuses weighing 5,700g or more is crucial for optimizing perinatal outcomes.
• Risk factors such as maternal height, parity, pre-pregnancy weight, and weight gain have limited predictive value for identifying macrosomic fetuses.
• Current obstetric practices show limited awareness and preparedness for managing extremely large fetuses.

Purpose of the Study:

• To assess the effectiveness of existing methods for identifying fetuses with birthweights of 5,700g or greater.
• To analyze perinatal mortality and morbidity associated with different delivery modes for macrosomic infants.
• To provide evidence-based recommendations for the management of extremely large fetuses.

Main Methods:

• Retrospective analysis of 110 newborns with birthweights ≥5,700g in Sweden (1973-1984).
• Utilized the National Medical Birth Registry for case identification and selection of a reference population.
• Compared outcomes based on delivery mode (vaginal vs. cesarean section).

Main Results:

• Predictive potential of risk factors for identifying individual cases of extremely large fetuses was low.
• Elective cesarean section was performed in only 6.4% of cases; 70.9% underwent vaginal delivery.
• Vaginal delivery was associated with high rates of shoulder dystocia (nearly 40%) and brachial plexus injury (11 cases).
• Four of eight fetal deaths were linked to shoulder dystocia.

Conclusions:

• Current methods are insufficient for reliably identifying fetuses weighing 5,700g or more antenally.
• Abdominal delivery (cesarean section) is favored for extremely large fetuses due to high risks associated with vaginal birth.
• Management strategies should prioritize cesarean delivery to mitigate severe perinatal complications in macrosomic infants.