National Women's Annual Clinical Report 2010

The rate of multiple pregnancy remains stable over the last six years, with triplet
pregnancies following this trend. Triplet pregnancies include all women from ADHB and
WDHB area as the ADHB Maternal-Fetal Medicine Unit provide care to women from
WDHB. The majority of triplet pregnancies are spontaneous.
The perinatal mortality rate is higher than singletons (13.4/1000 births) as expected. It is
uncertain what proportion of twins are monochorionic and dichorionic, which have
different perinatal mortality rates in the literature.
Twin perinatal mortality rate/1000
120
100
80
60
40
20
0
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Figure 24: Twin perinatal mortality 1997-2010 with 95% confidence intervals
Table 23: Mode of onset of birth among twin pregnancies
Preterm births
N=192
Term births
N=106
n % n %
Mode of onset of birth
CS elective 78 40.6 38 35.8
CS emergency before labour 38 19.8 12 11.3
Induction of labour 26 13.5 48 45.3
Spontaneous labour 50 26.0 8 7.5
As expected the majority of twin pregnancies are preterm. For those where term is
reached there is no clear guidance on the best gestation at which to deliver twins and
NWH are part of a multicentre study which aims to answer this question.
One third of twin pregnancies result in both twins being delivered vaginally compared with
54% in 2000, which is a statistically significant reduction and indicates that Caesarean
Section is now the norm. Of the 50 women having a first twin born vaginally, only one
woman had a Caesarean Section for the second twin. A 0.5% chance of Caesarean
Section for the second twin is very low and should be stressed to women considering
vaginal birth for twins. This may be due to a number of factors including case selection
and specialist attendance at delivery.
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