Early motivation

Dr. Rechberg founded Valley Electronics after his wife increasingly suffered from the side effects of the birth-control pill and he began looking for a hormone-free alternative.¹ He earned his doctorate at the University of St. Gallen (HSG) and initially worked as a management consultant before dedicating himself to developing a device of his own.¹

He was familiar with the basal body temperature (BBT) method of cycle tracking and recognized that measurement and interpretation could be automated by a computer. Together with the gynecologist Dr. Steinschulte and specialists in software, electronics and design, he built one of the world's first cycle computers.^1,2

1986: the Baby-Comp

In the early 1980s, Dr. Rechberg began developing a computer-based system for cycle tracking. In 1986 he founded Valley Electronics in Bavaria, Germany; that same year the BABY-COMP 1.0 was created, manufactured by AEG in Berlin.^1,2

The operating principle was already the same as it is today: the fertile window typically falls in the days leading up to and around ovulation, and after ovulation the basal body temperature rises slightly due to hormonal changes. The Baby-Comp detected this rise and displayed red for fertile days, yellow for the learning phase and green for non-fertile days.¹

The first Baby-Comp was sold in Switzerland in 1987, with additional markets following from 1988. In 1998 the device family was studied for the first time in an independent clinical study led by Prof. Dr. G. Freundl (Freundl et al.).³

The Baby-Comp was the first device to automate the interpretation of a temperature curve. Previously, a woman had to read the baseline and the temperature shift by hand from a paper chart. This core principle, the automated interpretation of basal body temperature and cycle data by a self-learning algorithm, is known today as the fertility-tracker method and is still used in every Valley Electronics device.

The fertility-tracker method

Lady-Comp: the second device generation

Together with an electronics engineer from California and an industrial designer from Munich, we developed a smaller, disc-shaped generation of devices (approx. 3 x 14 cm).¹ This phase gave rise to the name Lady-Comp, alongside the still-available Baby-Comp: the Baby-Comp remained intended for women trying to conceive, the Lady-Comp for women who wanted a hormone-free approach to family planning.¹ The thermal sensor achieved an accuracy of 0.05 °C.¹

More about Lady-Comp

Backed by science

The device family has since been examined in several peer-reviewed studies. Freundl et al. studied 648 women from Germany and Switzerland. A method-related Pearl Index of 0.7 was reported; overall use effectiveness in the study was 3.8 by Pearl Index.³ This distinction matters, because real-world effectiveness also depends on correct and consistent use.

Binkiewicz et al. (2010) calculated a Pearl Index of 0.64 based on 2,040 cycles in the Polish market.⁴ Demiańczyk and Michaluk (2016) reported a Pearl Index of 0.4989 across ten years and 17,322 cycles.⁵ Van de Roemer, Haile and Koch (2021) analyzed a decade of firmware performance data from Daysy users (107,020 cycles); this study evaluates algorithm performance in cycle classification, not contraceptive effectiveness.⁶

Our device family has been studied continuously in independent, peer-reviewed research since the 1990s. This continuity and independence across more than two decades is rare in cycle tracking.

Studies

Continued development and new products

Software and hardware development took place in Germany throughout. Over the years we substantially reworked both, including an integrated battery for the first time.¹

In 2004 we launched the Pearly, an oval device with a fold-out sensor.¹ In 2005 we filed with the U.S. FDA; in April 2006, Lady-Comp USA received 510(k) clearance for ovulation prediction and to aid conception.⁷ For clarity: the 510(k) clearance covered a computerized basal body temperature thermometer for ovulation prediction and to aid conception; the FDA documentation does not list any indication for contraception.⁷

In 2008 our devices were additionally certified as medical devices under European law.⁸

Carried forward by the next generation

Dr. Rechberg's daughter Natalie Rechberg joined the family business in 2008 and took over as CEO in 2013. She leads Valley Electronics today in its second generation. In 2014 she led the family's biggest product leap with Daysy, app-connected from the start; in 2015 the Lady-Comp received its first color display, and Daysy 2.0 followed in 2019. With Teena, a cycle tracker designed specifically for teenagers was added, helping young people understand their cycle from the very beginning.^1,2

The core principle stayed the same: measure under the tongue, interpret in red, yellow and green. We have been building cycle-tracking devices in Germany since 1986, certified as medical devices under European law since 2008, with over 10 million cycles analyzed and more than 40 years of continuous refinement.

Today the product family accompanies women through every stage of life, from a first period with Teena through trying to conceive and into menopause.

Legacy

Dr. Hubertus Rechberg passed away on September 24, 2019, at the age of 71. The clinical study he initiated on the Baby-Comp/Lady-Comp (Freundl et al., 1998) is still cited as a foundational reference in the scientific literature on fertility-awareness methods, including in studies of later cycle apps such as Natural Cycles (Berglund Scherwitzl et al., 2016).³

With the core principle he developed, automated temperature interpretation with a red-yellow-green classification, he laid the foundation that other digital fertility trackers still build on today.

His 1986 Baby-Comp is also part of the traveling exhibition Designing Motherhood, shown at the MassArt Art Museum Boston, the Mütter Museum Philadelphia and the Museum of Arts and Design New York, where it is catalogued under his name.²

Understand your body like never before

Every device we build today works on the same principle Dr. Rechberg established in 1986. In less than a minute a day you know where you are in your cycle, and gain valuable insights that support your goals around fertility and cycle health.

Medical device

Daysy: Precise. Compact. Practical. The ideal cycle computer for on the go, with a free app. No subscription.

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Medical device

Lady-Comp: No app. No Bluetooth. The cycle computer with all your data on the device, fully offline. No subscription.

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For Teenagers

Teena: Be period ready. Your cycle tracker made for teenagers, with a free educational app. No subscription.

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Sources

1)

Valley Electronics. Company history and internal documentation. Valley Electronics.

2)

Museum of Arts and Design (MAD). Designing Motherhood: Things That Make and Break Our Births — Gallery Guide. Museum of Arts and Design, New York. 19-20 (2025).

Available at: madmuseum.org .

3)

Freundl, G.; Frank-Herrmann, P.; Godehardt, E.; Klemm, R.; Bachhofer, M. Retrospective Clinical Trial of Contraceptive Effectiveness of the Electronic Fertility Indicator Ladycomp/Babycomp. Advances in Contraception. 14(2), 97-108 (1998).

DOI: 10.1023/A:1006534632583. Available at: link.springer.com .

4)

Binkiewicz, P.; Michaluk, K.; Demiańczyk, A. Calculation of the Pearl Index of Lady-Comp, Baby-Comp and Pearly cycle computers used as a contraceptive method. Ginekologia Polska. 81(11). (2010).

Available at: journals.viamedica.pl .

5)

Demiańczyk, A.; Michaluk, K. Evaluation of the effectiveness of selected natural fertility symptoms used for contraception: estimation of the Pearl index of Lady-Comp, Pearly and Daysy cycle computers based on 10 years of observation in the Polish market. Ginekologia Polska. 87(12), 793-797 (2016).

DOI: 10.5603/GP.2016.0090. Available at: journals.viamedica.pl .

6)

van de Roemer, N.; Haile, L.; Koch, M.C. The performance of a fertility tracking device. The European Journal of Contraception & Reproductive Health Care. 26(2), 111-118 (2021).

DOI: 10.1080/13625187.2021.1871599.

7)

U.S. Food and Drug Administration. 510(k) Premarket Notification K050094 (Lady-Comp USA). FDA. (2006, April 20).

Available at: www.accessdata.fda.gov .

8)

DEKRA Certification GmbH. EC certificate for the Quality Assurance System per Directive 93/42/EEC, Annex II (VE Valley Electronics GmbH). Cert. reg. no. 51210-16-00 (2008).