[Suspected large fetus in the last period of pregnancy--a difficult problem]

In pregnancy surveillance a large symphysis-to-fundus measure raises several questions concerning delivery.

We review various problems with large for gestation age foetuses, also called macrosomic foetuses. We have performed literature searches mainly through PuBMed, which includes the Medline database. The clinical problem is discussed from the primary care provider's point of view and from those of the patient and the obstetrician.

Macrosomia is defined as foetal weight above the 90th percentile, birth weight above 4000 g or 4500 g, or birth weight over + 2 SD of the mean birthweight by age. The diagnosis is difficult, even with various sonographic procedures. Abdominal circumference alone appears to have the same diagnostic value as the use of a combination of biparietal diameter, femur length and abdominal circumference.

Based on the literature, labour should not be induced or caesarean section performed in non-diabetic pregnancies unless the estimated foetal weight is above 5000 g. A great number of caesarean sections would have to be performed to avoid a single case of plexus brachialis paresis due to difficult shoulder delivery. The best policy is to await spontaneous birth or to induce birth after the completion of 42 weeks. In pregnancies complicated by diabetes mellitus, there are reasons for selective induction of labour if macrosomia is suspected, and for caesarean section if the calculated birth weight is above 4000 g. As the problem of difficult shoulder delivery cannot be completely avoided, each department should have a strategy to handle such a situation. Various procedures for managing the difficult shoulder delivery are described.