Clearblue offers a range of ovulation test and fertility products, all of which monitor luteinizing hormone (LH) in urine to identify the time of peak fertility. The Clearblue Fertility Monitor and Clearblue Advanced Digital Ovulation Test also measure another key hormone, estrogen (estrone-3-glucuronide) to identify the period of high fertility that occurs prior to the LH surge. Monitoring these two hormones helps women identify the fertile days of their cycle enabling them to time intercourse to the days when conception is most likely.
How urinary LH and E3G can be used to identify fertile days
There are only a few days per cycle when a woman is fertile and can conceive. Evidence shows that this time of high fertility usually spans 6 days, starting approximately 5 days prior to ovulation and ending on the day of ovulation itself.1 The 6-day fertile period is affected by:
- The lifespan of the egg, which is up to 24 hours after ovulation
- The lifespan of sperm which is more variable. The median is 1.5 days, but sperm can survive up to 5 days in the sperm supportive mucus found in the fertile days of the cycle. Sperm survival is therefore dependent on the type and quantity of the mucus within the cervix, and the quality of the sperm itself.
The two most fertile days of this 6-day window are known as peak fertility days. These peak fertile days are the day prior to ovulation and the day that ovulation takes place.2
Studies show that a surge in LH levels occurs 24-36 hours prior to ovulation,2 and that this LH surge is an accurate and reliable marker of impending ovulation.3-7 The urinary LH surge pinpoints the two peak fertile days of a woman's cycle, with intercourse on these days being shown to be associated with the highest likelihood of conception.1
In the days leading up to the LH surge, estradiol levels rise gradually, reaching a threshold that triggers the preovulatory LH surge. Tracking E3G, the urinary metabolite of estradiol, allows women to identify the days of high fertility leading up to ovulation, where conception is also possible, and this also gives them advanced notice of their peak fertile days. Data show that women who are aware of their fertile days have an increased likelihood of conceiving.8,9
Furthermore, estradiol stimulates secretion of cervical mucus that is favorable for the survival and transport of sperm. The rise in plasma estradiol corresponds closely to the appearance of sperm-supportive cervical mucus.10 Therefore, intercourse during the 6-day fertile period may lead to conception, as sperm can survive for a number of days.
The Clearblue Fertility Monitor is a unique innovation proven to help reduce the time it takes to conceive.11 It accurately monitors levels of LH and E3G to typically identify 6 days of high and peak fertility per cycle. This makes the Clearblue Fertility Monitor the most advanced home method of maximizing the chance of conception. Clinical studies have found urinary measurements by Clearblue Fertility Monitor closely reflect serum concentrations of the hormones6 and the LH surge detection by the monitor accurately predicts ovulation.5
The Clearblue Advanced Digital Ovulation Test accurately tracks a woman's personal menstrual cycle to identify a wider fertile window than other home ovulation tests, by tracking the changing levels in the urinary metabolites of E3G and LH. By measuring these 2 hormones, the Clearblue Advanced Digital Ovulation Test typically identifies 4 fertile days, 2 more than any other ovulation test, for more opportunities to get pregnant naturally.12 The Clearblue Advanced Digital Ovulation Test is more than 99% accurate at detecting the LH surge.13 The digital display shows an unmistakable result in the form of a smiley face when a fertile day is detected.
The Clearblue Digital Ovulation Test is over 99% accurate in detecting the presence of LH in the urine sample.14 The Clearblue Digital Ovulation Test identifies the two most fertile days by detecting this pre-ovulatory LH surge. It is a simple home ovulation test kit, which provides easy-to-read, easy-to-understand digital results for more accurate reading in consumers' hands.15
The Clearblue Digital Ovulation Test is available as a 7 Test Pack and a 20 Test Pack. The Clearblue Digital Ovulation Test - 20 Test Pack is more suited for women with irregular cycles, as it includes extra test sticks to give women a greater chance of detecting their peak fertile days.16 Data show that over 40% of women experience more than 7 days cycle variability, 17 and for these women, using the 7 test pack may mean they miss their LH surge if they test on the wrong day. The Clearblue Digital Ovulation Test - 20 Test Pack is very easy to use as the consumer starts testing on day six (or day 12 if a typical cycle is longer than 40 days) and keeps testing each day until her LH surge is detected. Because of these extra test days, in 99% of cases a test would be conducted on the surge day (if present).16
Please note, the Clearblue Digital Ovulation Test 20 Test Pack is being re-launched as a 2 month supply pack and will be available simultaneously with the current one during a transition period. The new 2 month supply pack has a variable start day depending on cycle length. Please consult package insert of product before use or contact us for additional support.
The Clearblue Ovulation Test is a traditional ovulation test which is an accurate method to identify the LH surge day and improve a woman's chances of conceiving.
This content is provided for general information purposes only. Always read package insert of product before use.
1 Wilcox AJ, Weinberg CR, Baird DD. Timing of sexual intercourse in relation to ovulation. Effects on the probability of conception, survival
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2 Ferreira-Poblete A. The probability of conception on different days of the cycle with respect to ovulation: an overview. Adv Contracept 1997 Jun;13(2-3):83-95.
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5 Behre HM, Kuhlage J, Gassner C, Sonntag B, Schem C, Schneider HP, et al. Prediction of ovulation by urinary hormone measurements with the home use ClearPlan Fertility Monitor: comparison with transvaginal ultrasound scans and serum hormone measurements. Hum Reprod 2000;15(12):2478-82.
6 Tanabe K, Susumu N, Hand K, Nishii K, Ishikawa I, Nozawa S. Prediction of the potentially fertile period by urinary hormone measurements using a new home-use monitor: comparison with laboratory hormone analyses. Hum Reprod 2001;16(8):1619-24.
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9 Stanford JB, Dunson DB. Effects of sexual intercourse patterns in time to pregnancy studies. Am J Epidemiol 2007 May 1;165(9):1088- 95.
10 Burger, HG. Estradiol: the physiological basis of the fertile period. Int J Gynecol Obstet 1989; Suppl 1:5-9.
11 Robinson JE, Ellis JE. Mistiming of intercourse as a primary cause of failure to conceive: results of a survey on use of a home-use fertility monitor. Curr Med Res Opin 2007;23(2):301-6.
12 SPD Data on file. In a study of 87 women,4 or more fertile days were identified in 80% of cycles using actual cycle length.
13 SPD Data on file. Study found >99% agreement with AutoDELFIA reference method in 100 cycles (all cycle had LH surge >40mIU/ml).
14 SPD data on file. Clearblue Digital Ovulation Test has been shown to be 99% accurate when compared to a reference method in laboratory studies using urine samples from 123 cycles in which the LH surge was identified by a reference method.
15 Johnson S, Ellis J, Godbert S, Ali S, Zinaman M. Comparison of a digital ovulation test with three popular line ovulation tests to investigate user accuracy and certainty. Expert Opin Med Diagn 2011;5:467-473.
16 Johnson SR, Shaw R, Success of detection of LH surge by home ovulation tests. Fertil Steril 2009:92(3):S101
17 Creinin MD, Keverline S, Meyn LA. How regular is regular? An analysis of menstrual cycle regularity. Contraception 2004 Oct;70(4):289-92.