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| Journal of the New Zealand Medical Association,
10-August-2012, Vol 125 No 1359
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Screening for sexually transmitted infections in
pregnancy at Middlemore Hospital, 2009
Alec J Ekeroma, Leena Pandit, Cecilia Bartley, Bettina
Ikenasio-Thorpe,
John M D Thompson
A sexually transmitted infection (STI) in pregnancy can lead
to preterm labour, premature rupture of membranes, stillbirths, small for
gestational age births, amnionitis, intrapartum fever, postpartum endometritis,
as well as vertical transmission causing neonatal conjunctivitis, neonatal
pneumonitis and perinatal mortality.1-4
Chlamydial infection of the urogenital tract is the
commonest STI and a significant health problem in New Zealand due to its high
prevalence rate of up to 12%5, the relative
lack of symptoms, and infected women may acquire complications that may persist
throughout their lifetime. There have been calls for routine testing in
pregnancy since Lawton et al6 found a
chlamydial prevalence rate of 4.8% in the Wellington area and Rose et
al7 found an STI rate of 10% in women
presenting for termination of pregnancy.
Instead of a screening programme, the Ministry of Health
(MOH) encouraged STI screening in pregnancy especially for Māori and
Pacific women and those under 25 years of age.8
Middlemore Hospital (MMH) of the Counties Manukau District
Health Board (CMDHB) delivered 6795 babies in 2009 and about 57% of the women
are of Māori or Pacific ethnicity. Of the Māori and Pacific women,
approximately 50% and 80% respectively, reside in NZDep2006 9 and 10
areas.9
About 55% of all women had CMDHB staff as their lead care
provider whilst private providers, who were exclusively self-employed midwives,
cared for the remaining 45%. The CMDHB
guidelines10 recommends that “all women
under the age of 25 should be offered testing when they access healthcare, in
particular when attending for sexual health related issues such as
pregnancy.”
There is a paucity of STI prevalence studies in pregnancy in
New Zealand and it is uncertain whether maternity providers are adhering to the
MOH and local facility guidelines.
The aim of this study is to determine the screening rate for
STIs in pregnancy and to determine the STI rate in pregnancy in an area that has
the highest number of Māori, Pacific and young people in the country.
Materials and MethodsA list of all 6795 women who had a delivery at MMH in
2009 was provided by Middlemore Hospital’s information support personnel.
The list, which was generated from the Patient Information Management System
(PIMS), had the details of the woman’s National Health Index (NHI) number,
age, ethnicity and LMC. These details were cross-checked with the data on the
Healthware database using the NHIs as the identifiers. The women’s NHIs
were then again used to individually search for their swab results on the
Web-Éclair database. There may have been a small number of results that
were not entered into the computer system at the patient’s request.
All data was entered into a Microsoft Excel 2003
spreadsheet. Comparison of swab rates and STI rates by categorical variables
(LMC, age group and ethnicity) was carried out using Chi-square statistics.
Univariable and multivariable odds ratios were estimated using unconditional
logistic regression. All analyses were carried out in SAS 9.1 for windows and
statistical significance was defined at the 5% level.
An antenatal STI screen was defined as endocervical and
vaginal swabs taken at any stage of the pregnancy and may include urethral
swabs. Urine and blood tests for chlamydia have a poor sensitivity and
specificity and were not considered appropriate for STI screening.
Approval from the Northern-X Regional Ethics Committee
was obtained.
ResultsScreening rate—Of the 6795 births in
MMH in 2009, 4635 women (64.3%) had screening for an STI during pregnancy.
European women had the lowest rate of screening with 1381 (49.6%) screened
whereas 1380 (66.3%) of Māori (OR 2.00) and 2919 (70.4%) of Pacific (OR
2.41) women were screened (Table 1). Not all women had
the full set of STI screening swabs.
Of the 4635 women tested, 3917 (82%) had chlamydia swabs,
3938 (85%) had trichomonas and 1529 (33%) had swabs for gonorrhoea. 52 women had
a urine test for chlamydia and 7 of them were positive.
STI screening by age group showed a pattern with less
screening with advancing age. 670 (74.5%) of women less than 20 years of age
were screened compared with 1124 (56.9%) of women 35 years of age and older
(p<0.0001).
Private maternity providers were less likely to perform
screening compared to CMDHB providers (54.0% vs 71.3%, p<0.0001).
Infection rate—Chlamydia was the
commonest STI in pregnancy. Of the 4635 women who had screening, 357 (8.2%) were
positive for chlamydia, 94 (2.2%) for trichomonas, and 10 (0.2%) for gonorrhoea.
STI in pregnancy was lowest in women of Asian (1.9%) and
European (4.7%) ethnicity and highest in Māori 93 (10.3%) and Pacific 219
(10.7%) women (Table 1). The multivariable odds ratio showed Pacific women had a
2.15-fold increased risk and Māori a 1.61-fold increased risk of an STI
compared to European women. Trichomonas infection was also higher in
Māori (3.0%) and Pacific (3.1%) women compared to European (0.4%) and Other
(0.0%).
Chlamydial infection was highest in younger women compared
to older women. 497 (21.7%) of women less than 20 years of age had chlamydial
infection compared to 633 (1.3%) women 35 years and older with positive swabs.
Women under 20 years of age had a 23-fold increased chance of having a
chlamydial infection compared to a 35-year-old woman (Table
2). There was a decreasing rate of both chlamydia and trichomonas as age
decreased, the increasing risk with younger maternal age remained significant in
multivariable analyses but was not of the same magnitude as for trichomonas.
Where chlamydia or trichomonas was present, there was a 6.73
(95%CI=4.23–10.68)-fold increased chance that the other STI was present.
Rate of chlamydial infection was lower in women cared for by
a private provider (2.1%) compared to a CMDHB provider (6.1%).
DiscussionThe MOH 2008 Chlamydia Management
Guidelines8 advise routine testing in pregnancy
“as there is a 20-50% risk of neonatal transmission in women with
untreated chlamydial infection”. The words screening or
programme were not used following a report to the National Screening
Unit5 despite calls for routine screening after
two research papers found high chlamydial rates in women presenting for
terminations of pregnancy7 and in
pregnancy.6
Studies in STI prevalence rates in pregnancy have been
lacking although a few studies have identified high risk groups in the less than
20 years of age, Māori and Pacific
women.11-16 There has equally been a lack of
studies to determine whether care providers were compliant with the MOH
guidelines and offering women STI testing in pregnancy.
Our study has shown that only 64% of women had STI screening
in pregnancy and not all of them had the recommended set of three swabs to
exclude chlamydial, trichomonal and gonorrhoeal infection. Of serious concern is
the low screening rate for gonorrhoea with only 23% of all the 6795 women
screened. Swabs for chlamydia and gonococcus are taken from the endocervix so it
is uncertain as to why the screening rate for the former was 2.5 times higher
than the latter unless providers had decided not to screen for gonorrhoea in 49%
of women who had chlamydial swabs.
It was encouraging to note that women under 20 years of age
had more STI screening (75%, 2.2-fold) compared to women 35 years and older
(60%). Maternity providers were obviously aware that younger women were more at
risk. However, the shortfall in testing is of concern with 1 in 4 young women
not being tested. Extrapolating from the chlamydial infection rate in our study
for women under 20 years of age, approximately 36 women with chlamydia would
have been missed and untreated.
Pacific, Other and Māori women had higher screening
rates compared to European and Asian women, which may mean that the clinical
practice of maternity providers had taken into account the importance of
screening women from ethnicities with a high risk of an STI. There is a concern
however that 30% of Pacific women and 34% of Māori women were not tested
which was a significant number of untested women. Taking into account the
chlamydial infection rate in our study for Pacific and Māori women, there
would have been approximately 143 women in 2009 with chlamydia that was
untreated.
Chlamydia is a treatable infection and the resultant
morbidity of untreated chlamydia is totally preventable. The screening rate for
STI in pregnancy fell short of the MOH guidelines and although it was higher
than the screening rate of 37.5% in
Wellington,6 this should be expected as the MOH
guidelines8 were published in 2008.
Of interest was the finding that private providers performed
fewer tests compared to CMDHB providers and this difference was statistically
significantly. A study is needed to determine the factors behind this variation
in practice between private and public providers. It may be that a higher number
of the women booked with private providers were not interested in being tested
(different population characteristics) compared to women cared for by the public
system. It has been shown that women found testing
acceptable.15 It may also be that the private
providers had decided that most of their clientele were low risk and therefore
did not need to be tested.
The latter is probably a safer assumption as the rate of
chlamydial infection in women cared for by the private providers (2.1%) was
lower than those cared for by the public system (6.1%). This can be explained by
the fact that more Pacific and Māori women, or women at high risk of having
an STI in pregnancy, are cared for by the public system, with lower risk women
choosing private carers (CMDHB data).
Chlamydia was the commonest STI in pregnancy with a
prevalence of 8.2%, which confirmed findings from New Zealand
studies5, that chlamydia remains a significant
disease burden. The infection rate was higher than that found in the Wellington
study6 which can be explained by the higher
proportion of Māori and Pacific women and women less than 20 years of age
resident in the CMDHB area compared to the Wellington
area.17
The trichomonas rate was also higher in both Māori and
Pacific women in comparison to European women, stressing the importance of
testing for all STIs especially in the high risk groups. The presence of one STI
increases the chances of another one being present.
The question of whether to universally screen in pregnancy
remains a contentious one. The British National Health Service recommended
targeted testing of at risk groups and the NICE guidelines recommended offering
screening to women 25 years and younger.18 The
guidelines were careful to state that the long-term complications of not testing
in pregnancy were not considered. The Centre for Disease Control and Prevention
in the USA in 2010 recommended routine testing for chlamydia in
pregnancy.19
The strength of our study was the large number of women in
an area with high socio-economic deprivation and the weakness was the inability
to estimate the number of women who may have opted out of sharing their
laboratory results.
Due to the significant under-testing found in our study, we
recommend that the MOH enforce adherence to STI testing guidelines especially
for Māori, Pacific and those less than 25 years of age.
Variations in testing uptake and rates should be urgently
addressed through awareness programmes and professional guidelines in
collaboration with DHBs.
Competing interests: None.
Author information Alec J Ekeroma, Senior
Lecturer1; Leena Pandit, Elective Medical
Student2; Cecilia Bartley, WHO
Fellow1; Bettina Ikenasio-Thorpe, Research
Fellow1; John M D Thompson,
Epidemiologist/Statistician3
Acknowledgements: We
thank Middlemore Hospital staff Lesley Powell and Fawcia Saleem for providing
hospital data and support information.
Correspondence: Alec Ekeroma, University of
Auckland, Middlemore Hospital, Private Bag 93311, Auckland, New Zealand. Fax:
+64 (0)9 5235253; email: Alec.Ekeroma@middlemore.co.nz
References:
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