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The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
A pilot study to assess the impact of obstructive sleep apnea (OSA) and treatment with continuous positive airway pressure (CPAP) therapy on maternal blood pressure and placental blood flow in high risk obstetric patients
Scientific title
A prospective cohort study to assess the impact of obstructive sleep apnea (OSA) and treatment with autotitrating continuous positive airway pressure (CPAP) therapy on maternal blood pressure and placental blood flow in severely obese obstetric patients
Secondary ID [1] 296739 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obstructive sleep apnea 310608 0
Maternal hypertension 310611 0
Condition category
Condition code
Respiratory 309322 309322 0 0
Sleep apnoea
Reproductive Health and Childbirth 309323 309323 0 0
Antenatal care
Cardiovascular 309386 309386 0 0

Study type
Description of intervention(s) / exposure
Autotitrating continuous airway pressure (CPAP) will be prescribed from a pressure of 4-20 cm H2O, for a minimum of 4 hours per night, to all pregnant women diagnosed with obstructive sleep apnea (as defined by an apnea-hypopnea index (AHI) of >10/hr) following a diagnostic polysomnogram and consultation with a sleep physician. Compliance to treatment will be individualized and assessed on a weekly basis by the sleep physician with the assistance of the sleep nurse and CPAP provider. Treatment with CPAP therapy will continue from the time of diagnosis of OSA up until 6 months post-partum following a repeat diagnostic sleep study.
Intervention code [1] 313046 0
Diagnosis / Prognosis
Intervention code [2] 313047 0
Treatment: Devices
Comparator / control treatment
Control group: pregnant patients with an early pregnancy body mass index (BMI) of 35 kg/m2 or more without OSA (as defined by an AHI of less than 10/hr)
Treatment group: pregnant patients with early pregnancy BMI of 35 kg/m2 or more with OSA (as defined by AHI of >10/hr) who will all be offered treatment with CPAP therapy
Control group

Primary outcome [1] 308286 0
Maternal blood pressure control as measured by manual sphygmomanometer/digital blood pressure cuff at clinic visits and recorded in the patient's medical notes.
Timepoint [1] 308286 0
For the duration of pregnancy, recorded at every pregnancy clinic appointment (20 weeks, 28 weeks, 32 weeks, 38 weeks, delivery and at any additional outpatient clinic appointments during pregnancy)
Secondary outcome [1] 354537 0
Maternal quality of life as assessed by AQOL-8 and the sleep apnea specific version SAQLI
Timepoint [1] 354537 0
At enrollment prior to 28, at 32 weeks gestational age and 3 months post partum
Secondary outcome [2] 354538 0
Placental vascular health (as measured by arterial doppler)
Timepoint [2] 354538 0
28, 32 and 36 weeks gestation age
Secondary outcome [3] 354539 0
Placental vascular health (assessed following delivery by histopathology)
Timepoint [3] 354539 0
at delivery
Secondary outcome [4] 354540 0
Pregnancy complications as documented in pregnancy health record, via patient report or from medical records including: gestational diabetes, gestational hypertension, preeclampsia, preterm delivery, emergency ceasarean section, admission to ICCU, neonatal ICCU admission, APGAR scores at birth, neonatal birth weight
Timepoint [4] 354540 0
Until delivery
Secondary outcome [5] 354541 0
Persistence of obstructive sleep apnea as assessed by a repeat diagnostic polysomnogram
Timepoint [5] 354541 0
6 months post partum

Key inclusion criteria
Early pregnancy BMI of 35 kg/m2 or more
Gestational age less than 28 weeks
Ability to given informed consent
Minimum age
18 Years
Maximum age
55 Years
Can healthy volunteers participate?
Key exclusion criteria
Lack of regular attendance at clinic appointments
Illicit or intravenous drug use
Current cigarette smoking
Known diagnosis of OSA already established on CPAP therapy
Type 1 diabetes mellitus
Pulmonary hypertension

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
A prospective cohort of high risk women will be followed during pregnancy and investigated for OSA. Those diagnosed with OSA will be offered treatment with CPAP therapy (non-randomized, non-blinded). All patienst will receive standard obstetric care for the duration of pregnancy and undergo maternal blood pressure assessment at regular clinic visits and ultrasound assessments at 28, 32 and 36 weeks gestational age.
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
We anticipate a difference of 15 mmHg blood pressure readings between those participants who are compliant with CPAP therapy compared to those who are unable to tolerate this treatment. We estimate that a total sample of 58 participants with OSA (29 per group) completing the study would be sufficient to detect a post-treatment change in systolic blood pressure in the order of 15 mmHg between groups with 80% power and a 2-sided type I error of 0.05. This would be a modest and clinically important effect. Allowing for around ~10% attrition we have selected a total sample of 70 (35 per group). Should the effect size be smaller, this study would remain important for establishing feasibility and pilot data needed to help attract funding and refine study power for a larger study. We will use mixed effect model analysis in SPSS to test these hypotheses. This allows for repeated measures over time and adjustment for relevant co-variates.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 12598 0
Flinders Medical Centre - Bedford Park
Recruitment postcode(s) [1] 24972 0
5042 - Bedford Park

Funding & Sponsors
Funding source category [1] 301320 0
Name [1] 301320 0
Flinders Medical Centre
Address [1] 301320 0
2 Flinders Drive
Bedford Park, SA
Country [1] 301320 0
Primary sponsor type
Flinders Medical Centre
2 Flinders Drive
Bedford Park SA
Secondary sponsor category [1] 300984 0
Commercial sector/Industry
Name [1] 300984 0
Philips SleepEasy Centre
Address [1] 300984 0
116-118 Beach Rd, Christies Beach SA 5165
Country [1] 300984 0

Ethics approval
Ethics application status
Ethics committee name [1] 302061 0
Southern Adelaide Clinical Human Research Ethics Committee
Ethics committee address [1] 302061 0
2 Flinders Drive
Bedford Park, SA
Ethics committee country [1] 302061 0
Date submitted for ethics approval [1] 302061 0
Approval date [1] 302061 0
Ethics approval number [1] 302061 0
HREC/18/SAC/31 OFR number 28.18

Brief summary
The study will follow a cohort of high risk pregnant women and assess for and treat OSA with CPAP therapy. Maternal blood pressure will be monitored throughout pregnancy and is the primary outcome between the two groups of participants (those with OSA compared with those without OSA). Quality of life will be assessed during pregnancy to determine if treating OSA improves quality of life. Placental vascular health will be monitored via ultrasound assessment at 28, 32 and 36 weeks gestational age followed by pathological examination of the placenta following delivery. Those women with a diagnosis of OSA during pregnancy will be reassessed for persistence of OSA at 6 months post partum.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 88990 0
Dr Sarah Newhouse
Address 88990 0
Respiratory and Sleep Services
Flinders Medical Centre
2 Flinders Drive
Bedford Park, SA
Country 88990 0
Phone 88990 0
+61 08 8204 5511
Fax 88990 0
+61 08 8204 5632
Email 88990 0
Contact person for public queries
Name 88991 0
Dr Sarah Newhouse
Address 88991 0
Respiratory and Sleep Services
Flinders Medical Centre
2 Flinders Drive
Bedford Park, SA
Country 88991 0
Phone 88991 0
+61 08 8204 5511
Fax 88991 0
+61 08 8204 5632
Email 88991 0
Contact person for scientific queries
Name 88992 0
Dr Sarah Newhouse
Address 88992 0
Respiratory and Sleep Services
Flinders Medical Centre
2 Flinders Drive
Bedford Park, SA
Country 88992 0
Phone 88992 0
+61 08 8204 5511
Fax 88992 0
+61 08 8204 5632
Email 88992 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Patient confidentiality regarding CPAP adherence/pregnancy related complications which has not been included in the patient informed consent sheet
What supporting documents are/will be available?
Informed consent form
Ethical approval
How or where can supporting documents be obtained?
Type [1] 563 0
Ethical approval
Citation [1] 563 0
Link [1] 563 0
Email [1] 563 0
Other [1] 563 0
Type [2] 565 0
Informed consent form
Citation [2] 565 0
Link [2] 565 0
Email [2] 565 0
Other [2] 565 0
Summary results
No Results