ISSN No. 1606-7754                   Vol.12 No.3  December 2004

Determinants for Macrosomia in a Mediterranean Island community
C. Savona-Ventura, M. Chircop
Diabetic Pregnancy Joint Clinic, Department of Obstetrics-Gynaecology, St. Luke's Teaching Hospital, Malta


Macrosomia has been associated with patient socio-biological determinants and poses increased perinatal risks to mother and child. The study set out to identify these determinants and assess the risk in a high NIDDM prevalence population. Maternal biological characteristics and obstetric outcomes of 988 infants weighing more than 4000 gm were statistically compared to similar parameters of 15653 infants of lower birth weight. Macrosomia appeared to be commoner in the older obese previously diabetic woman aged more than 30 years who had at least one previous pregnancy or miscarriage. Hypertensive disease was a negative correlate. The macrosomic infant was more likely to require an operative intervention for delivery. The delivery was similarly more likely to be complicated by shoulder dystocia. The tendency for macrosomia appears to be related to maternal insulin-resistance metabolic syndrome; while the infant size predisposed to definite intrapartum problems. Effective intervention therapies to combat excessive fetal growth need to be identified and introduced in clinical practice to prevent the long-term consequences of macrosomia to the infant.

Keywords: macrosomia, pregnancy, outcome, complications


A macrosomic infant is generally defined as one with a birth weight greater than the 90th centile for that population, a definition that includes all infants born with a birth weight greater than 4000 gm. The incidence of fetal macrosomia varies from one community to another and furthermore has shown temporal changes in the same community. The different incidence patterns suggest that patient socio-biological factors may play a determinant role in the development of macrosomia. Macrosomic babies have been associated with maternal diabetes and obesity; while the larger size of the infant imposes greater risks of birth trauma to the infant and the necessity of operative intervention to achieve a safe delivery.1,2,3

The Maltese population comprises a small island community in the Central Mediterranean with a high prevalence of maturity onset diabetes mellitus reflected in a high prevalence of gestational glucose intolerance.4,5 The incidence of fetal macrosomia, defined as a birth weight greater than 4000 gm, in this population has been reported to have decreased from 11.5% in 1983-86 to 5.9% in 1999-2002. While this fall may partly be attributed to an increase in the obstetric intervention rate with earlier timing of delivery, changes in the socio-biological characteristics of the mothers such as age at delivery patterns may also have played a determinant role.6 The aim of the study was to identify the maternal factors that may predispose towards fetal macrosomia and to study the outcome of these fetuses.

Material & methods

The study reviewed the medical data records of all women delivering in the Maltese Islands during 1999-2002 [n = 16,413 maternities resulting in 16,641 births]. The medical data was made available by the National Obstetric Information System managed by the Department of Health Information [Malta]. The medical records revealed a total of 988 infants born with a birth weight equal to or greater than 4000 gm divisible into 861 infants weighing 4000-4499 gm and 127 infants weighing >4500 gm. The maternal biological characteristics and obstetric outcomes of these infants were compared between each group and with those of infants weighing less than 4000 gm. The latter group include macrosomic infants for their gestational age but less than 4000 gm. Further comparison was made with the outcome parameters of the remaining background population delivering during the same period who presumably had a birth weight less than 4000 gm. The data analysis was carried out using SPSS package with statistical significance being tested using the Chi Square test generally using a 3-table comparison unless specifically indicated. A probability value of <0.05 was taken to represent a significant correlation.

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