Home pregnancy test compared to standard-of-care ultrasound dating in the assessment of pregnancy duration

Abstract

Objective:

To determine the level of agreement between the Clearblue Digital Pregnancy Test with Conception Indicator home pregnancy test and standard-of-care ultrasound in assessing pregnancy duration in a real-life, observational setting encompassing routine, clinical care.

Research design and methods:

This was a prospective observational study of non-pregnant women seeking conception. Women collected daily urine samples from day 1 of their next menstrual cycle. If any volunteer became pregnant, daily urine samples continued to be collected for 43 days after the LH surge. Samples from day −7 to day +28 relative to the expected period (LH surge + 15 days) were tested using the home pregnancy test. This categorised any resulting pregnancies into one of three groups: 1–2 weeks, 2–3 weeks, and 3+ weeks since conception. Information from the standard UK ultrasound dating scan was also recorded by the midwife, including the expected delivery date according to ultrasound and the expected delivery date according to LMP.

Main outcome measures:

Full data were available from 52 pregnant women who had conceived naturally. During the study analysis, 4786 urine samples were cross-compared with 52 routine 12-week NHS ultrasound assessments and the level of agreement between home pregnancy testing and standard-of-care ultrasound in determining pregnancy duration was calculated.

Results:

The agreement between the gestational age as calculated by the home pregnancy test result and the exact midwife-recorded gestational age using ultrasound was 82.3%. However, when a ±5-day range was applied to the ultrasound reading (as per routine UK clinical practice), the level of agreement was 98%.

Conclusions:

The home pregnancy test provides a significantly high (98%) level of agreement with standard-of-care ultrasound when assessing pregnancy duration in a real-life, observational setting which closely mirrors daily clinical practice.

Key words::

• Conception
• Gestation
• hCG test
• Pregnancy
• Ultrasound

Transparency

Declaration of funding

This study was funded by SPD Swiss Precision Diagnostics GmbH, Geneva, Switzerland.

Declaration of financial/other relationships

B.S., P.P. and S.J. have disclosed that they are employees of SPD, UK. J.E. has disclosed that she is an employee of SPD, Switzerland. P.B. has disclosed that he is a retired Director, GeneCare Medical Genetics Center, Chapel Hill, NC, USA. M.Z. has disclosed that he is an independent OBGYN clinician, registered and practicing in the USA. Both P.B. and M.Z. have disclosed that they received consultancy fees for their intellectual contribution to this study from SPD.

Acknowledgements

The authors thank IMC Healthcare Communication for their assistance in preparing this manuscript, funded by SPD.

The data in this paper were previously presented as ‘Agreement between the new Clearblue digital pregnancy test and ultrasound dating scan in assessing pregnancy duration (0–278)’, presented orally by S.J. at the European Society of Human Reproduction and Embryology, Rome, Italy, 23–27 June 2010.

Notes

*Clearblue Digital Pregnancy Test with Conception Indicator manufactured by SPD GmbH, Geneva, Switzerland.

*Clearblue Digital Pregnancy Test with Conception Indicator manufactured by SPD GmbH, Geneva, Switzerland.