8








Description of the babies

 
     
 

KEY FINDINGS

  • Over one-third of all babies were born prematurely.
  • Over half of singleton babies were over the 90th centile for birth weight adjusted for gestation, sex of baby and parity of mother.
  • There was an increased incidence of both shoulder dystocia and Erb's palsy.
  • Over half of all babies were admitted to a neonatal unit.
 
 
 

8.1

 

Introduction

Babies born to women with diabetes are at increased risk of adverse neonatal outcomes, including neonatal death, prematurity, hypoglycaemia and respiratory disorders, and also experience a higher prevalence of macrosomia compared with the general population.1 - 5 They also have an associated increased risk of shoulder dystocia and birth trauma.6 This chapter provides a description of the babies born to women in this study and some of these adverse outcomes. No specific questions were included in the data collection tool to look specifically at neonatal hypoglycaemia or respiratory disorders. Findings relating to standards of care for the babies are described in Chapter 9.

 
 

8.2

 

Sex of the baby

Sex was recorded in 3528/3538 (99.7%) of all live births and stillbirths. The sex ratio in the study population (male : female) was 1.03 compared with 1.05 in the general population.7

 
 

8.3

 

Gestation

This section includes information on all births after 24 weeks of gestation, comprising 3449 live births and 87 stillbirths. A total of 1296/3536 (36.7%) babies delivered preterm (less than 37 completed weeks of gestation) (Table 8.1) compared to a preterm delivery rate of only 7.3% in England and Wales for 2002–03.8 The majority of these preterm babies were born between 32+0 and 36+6 weeks of gestation. Twenty-six liveborn babies born after 24 completed weeks subsequently died in the neonatal period, of which 22 were born preterm. The details of these deaths, including cause of death, were not available from this dataset but will be examined as part of the enquiry module of the CEMACH diabetes project.

 
 

8.4

 

Birth weight

Macrosomia (birth weight 4000 g and over) is a recognised complication for babies of women with diabetes. In this study population, 714/3405 singleton births (21.0%) with a known birth weight had a birth weight of 4000 g or more compared with only 11.0% of singleton births nationally in 2002–03.8 A total of 201 (5.7%) singleton babies were classified as severely macrosomic (birth weight 4500 g or over).

There was no significant difference between the birthweight distributions of singleton babies born to women with type 1 diabetes compared with that of singleton babies born to women with type 2 diabetes (P =0.308) (Figure 8.1).

Birthweight centiles were applied to all singleton births with a known birth weight, adjusting for the sex of baby, parity of mother and gestation at delivery, based on the population of Aberdeen in the 1980s.9 Of the 3251 babies for whom it was possible to apply a birthweight centile, 1679 (51.7%) were at or above the 90th centile for gestational age. Only 84 babies (2.6%) were below the tenth centile for gestational age.

 
 

8.5

 

Shoulder dystocia and birth trauma

 
 

8.5.1

 

Shoulder dystocia

Shoulder dystocia was documented in 89 of the 1124 singleton vaginal deliveries (7.9%). This compares with 3% in large regional published data.10 The incidence of shoulder dystocia by birth weight is shown in Table 8.2. For babies with a birth weight between 4250 g and 4499 g the incidence of shoulder dystocia was 25.0% compared with published figures of only 9.1% in non-diabetic pregnancies in this weight range.10

When gestation-specific birthweight centiles were applied as before, 75 (84.3%) of all babies who had shoulder dystocia were at or above the 90th centile for gestational age.

These incidences may be influenced by increased reporting of shoulder dystocia when the babies are anticipated to be large.

 
 

8.5.2

 

Erb's palsy

There were 16 cases of Erb's palsy reported. This gives an incidence of Erb's palsy in babies born to women with pre-gestational diabetes of 4.5 per 1000 births. This incidence of Erb's palsy is more than ten-fold greater than that for the general population of the United Kingdom reported in a study conducted by the British Paediatric Surveillance Unit in 1999, which gave an incidence of Erb's palsy of 0.42 per 1000 live births.11

Twelve of these babies were delivered vaginally with the remaining four delivered by caesarean section (two elective; two emergency). Eight of the babies were also recorded as having been delivered with shoulder dystocia. This gives a figure of 66.7% of vaginally delivered babies with Erb's palsy associated with shoulder dystocia. This compares with figures of 56% and 64% of all cases of brachial plexus injury recorded in two studies of births in which shoulder dystocia also occurred.10,11

 
 

8.5.3

 

Other birth trauma

Fractures were reported in eight babies – fractured humerus in five babies (four with associated shoulder dystocia) and three babies with fractured clavicles (one with associated Erb's palsy).

An additional 60 babies were documented as having some other form of birth trauma with the most common being bruising (27/60) and markings associated with assisted vaginal delivery (13/60).

 
 

8.6

 

Condition of babies at birth

Apgar scores at 5 minutes were known for 3421/3451 (99.2%) live births. Median Apgar score was 9 (Interquartile range 9, 10) and 2.6% of all live births had an Apgar score of less than 7 at 5 minutes. This compares with 0.76% in a large population-based register using the same cutoff point.12

 
 

8.7

 

Neonatal admission

Information was recorded on admission at any time after delivery to a neonatal unit for all babies. The admission pattern for infants of mothers with pre-gestational diabetes is shown in Table 8.3. Of the 3451 live births, 1945 (56.4%) were admitted to a neonatal unit. The median length of stay for all babies who received care away from their mothers was 4 days (interquartile range 2, 10).

Most preterm infants (less than 37 completed weeks of gestation) received some form of neonatal care (special care, high dependency care, intensive care or other specialist care), 960/1235 (77.7%).

One-third of all term infants (37 weeks of gestation and above) were admitted to a neonatal unit for special care compared with 10% in the general population.13 Reasons for these term babies' admissions can be found in Chapter 9. A higher proportion of term babies born to mothers with type 1 diabetes were admitted to a neonatal unit compared to those of mothers with type 2 diabetes (rate ratio 1.18; 95% CI 1.05–1.31; P = 0.003).

 
 

8.8

 

Conclusion

Over one-third of all babies in this study were born preterm, almost five times the rate seen in the general maternity population. This is, in part, linked to an increased incidence of induced preterm delivery (see Chapter 6).

Women with diabetes gave birth to larger babies than the general maternity population of England, Wales and Northern Ireland. Half of the babies were above the 90th centile for birth weight adjusted for gestation at delivery, sex of baby and parity of mother. This was associated with a two-fold increase in shoulder dystocia and a ten-fold increase in Erb's palsy.

Over half of all babies of women with diabetes were admitted to a neonatal unit. This high incidence of admission may be partly explained by the high rate of prematurity among these babies. However, one-third of all term babies were also admitted to a neonatal unit for special care (more so in women with type 2 diabetes), three times the national average (see Chapter 9).

 
     

References

  1. Casson IF, Clarke CA, Howard CV, McKendrick O, Pennycook S, Pharoah PO, et al. Outcomes of pregnancy in insulin dependent diabetic women: results of a five year population cohort study. BMJ 1997;315:275–8.
  2. Penney GC, Mair G, Pearson DW; Scottish Diabetes in Pregnancy Group. Outcomes of pregnancy in women with type 1 diabetes in Scotland: a national population-based study. BJOG 2003;110:315–18.
  3. Evers IM, de Valk HW, Visser GHA. Risk of complications of pregnancy in women with type 1 diabetes: nationwide prospective study in the Netherlands. BMJ 2004;328:915–18.
  4. Rennie JM, Roberton NRC. Textbook of Neonatology. 4th ed. Edinburgh: Churchill Livingstone; 2005.
  5. Williams AF. Hypoglycaemia of the Newborn. Review of the Literature. CHD/97.1. Geneva: World Health Organization; 1997 http://www.who.int/child-adolescent-health/publications/NUTRITION/WHO_CHD_97.1.htm].
  6. Johnstone FD, Myerscough PR. Shoulder dystocia. Br J Obstet Gynaecol 1998;105:809–10.
  7. Office for National Statistics. Birth Statistics: Review of the Registrar General on births and patterns of family building England and Wales, 2002. Series FM1 No. 31. London: HMSO; 2004 [www.statistics.gov.uk/statbase/Product.asp?vlnk=5768].
  8. Department of Health. NHS Maternity Statistics, England 2002–03. Statistical Bulletin 2004/10 [www.dh.gov.uk/PublicationsAndStatistics/Statistics/StatisticalWorkAreas/StatisticalHealthCare/StatisticalHealthCareArticle/fs/en?CONTENT_ID=4086521&chk=wV7ZSA].
  9. Campbell D, Hall M, Lemon J, Carr-Hill R, Pritchard C, Samphier M. Clinical birthweight standards for a total population in the 1980s. Br J Obstet Gynaecol 1993;100:436–45.
  10. Nesbitt TS, Gilbert WM, Herrhen B. Shoulder dystocia and associated risk factors with macrosomic infants born in California. Am J Obstet Gynecol 1998 Aug;179:476–80.
  11. Evans-Jones G, Kay SP, Weindling AM, Cranny G, Ward A, Bradshaw A, et al. Congenital brachial palsy: incidence, causes, and outcomes in the United Kingdom and Republic of Ireland. Arch Dis Child Fetal Neonatal Ed 2003;88:F185–9.
  12. Thorngren-Jerneck K, Herbst A. Low 5-minute Apgar score: a population-based register study of 1 million term births. Obstet Gynecol 2001;98:65–70.
  13. Macfarlane A, Mugford M. Birth Counts: Statistics of Pregnancy and Childbirth. 2nd ed. Oxford: National Perinatal Epidemiology Unit; 2000.