Shoulder Dystocia and Brachial Plexus Injury: A Population-Based Study

Abstract

The objective of this work was to identify and evaluate risk factors for shoulder dystocia and for brachial plexus injury in a population-based study. In all, 1,397 parturients with shoulder dystocia occurring in Sweden between 1987 and 1996 were identified among 1,076,545 deliveries using information stored in the Medical Birth Registry (MBR) of the National Board of Health and Welfare, Stockholm. Information is missing for about 1.0% of singleton deliveries in the MBR. Validation of the diagnosis ‘shoulder dystocia’ in the MBR was performed using data of 4 of 63 delivery units and was confirmed in 96.5% of the original medical records. A total of 368 infants had brachial plexus injury (26.3%). However, a considerable variation in the rate of recorded shoulder dystocia was evident when comparing the 63 delivery units throughout Sweden. Overall, the incidence was 1.3 per 1,000 deliveries. A close association was found between birth weight and shoulder dystocia, with an odds ratio (OR) over 30 for a birth weight ≧5,000 g. In the presence of maternal diabetes mellitus or gestational diabetes, the OR for shoulder dystocia was significantly increased in newborns weighing ≧4,000 g. The overall perinatal mortality because of shoulder dystocia was 1.2%. This was increased to 6.4% if the mother had diabetes mellitus. About 25% of all infants suffered a brachial plexus injury. This potentially serious injury even occurred in connection with birth by cesarean section, and an OR for plexus injury over unity was seen in 7 of 9 weight groups; a significantly increased OR was seen for birth weights ≧4,500 g. The birth weight is a strong risk factor for shoulder dystocia, as is diabetes mellitus. A considerable variation in the rate of shoulder dystocia was observed among the different delivery units, probably reflecting difficulties in definition. Brachial plexus injury is observed even after cesarean section, especially if the birth weight is ≧4,500 g.

Etiological risk factors for brachial plexus palsy

“…In Sweden the incidence of brachial plexus palsy as a birth injury is 1.3 per 1000 deliveries. 3 In England this incidence is even lower and it is less than 1 per 1000 deliveries. In the developing countries this incidence is 5 per 1000 deliveries.…”

“…The incidence of brachial plexus injuries vary from 1 to 5 on 1000 deliveries and depends on level of health care. In Sweden incidence of bracial plexus palsy as a birth injuries is 1,3 on 1000 deliveries, 3 in England it is less than 1 on 1000 deliveries, and in developing countries it is 5 on 1000 deliveries. 4 The risk factors for brachial plexus injuries during delivery may be divided in three categories: neonatal factors, maternal factors or some other characteristics of second stage of labor.…”

Gestational Diabetes and the Metabolic Syndrome

“…Acute maternal effects include pregnancy-induced hypertension and increased risk of Caesarian-section, while long-term consequences include increased risks of T2DM and CVD. Neonatal complications include fetal macrosomia and the associated risk of shoulder dystocia (Athukorala et al, 2007) which in turn can lead to neonatal musculoskeletal and brachial plexus injury (Christoffersson & Rydhstroem, 2002), while long-term sequelae are childhood obesity (Metzger, 2007), metabolic syndrome, and higher risk of T2DM and hypertension (Athukorala et al, 2007;Boney et al, 2005;Joffe et al, 1998;Leon, 1998;Metzger, 2007;Reece et al, 2009). Though practices vary, many countries recommend that all pregnant women be screened at 24 to 28 weeks' gestation with a 1-hour 50-g glucose challenge test (GCT), followed by a confirmatory 2-hour 75-g, or 3-hour 100-g oral glucose tolerance test (OGTT).…”

High birthweight and shoulder dystocia: the strongest risk factors for obstetrical brachial plexus palsy in a Swedish population‐based study

“…The most significant combined maternal and infant risk factors referred to in the literature are neonatal macrosomia and shoulder dystocia (9,12,(69)(70)(71). However, there are also reports contradicting an increase in OBPP with increasing birth weight (72).The definition of macrosomia is not universal; cut-off points vary between 4000 g, 4500 g and 5000 g. The risk of shoulder dystocia due to macrosomia must be related to the mother's size and the capacity of her pelvis; the risk of shoulder dystocia thus varies with maternal height (73). Several studies have…”