UK-based Cambridge Temperature Concepts raised $4.38 million (£2.6 million) in a round led by Longwall Venture Partners.

The company previously raised just over $5 million (£3 million), CEO Dr. Claire Hooper told MobiHealthNews in an email. This brings the company's total funding to date to around $9 million.

Cambridge Temperature Concept's flagship product, called DuoFertility, is a stick-on sensor and handheld reader device that tracks specific biometrics like temperature to help women conceive. The company offers three different levels of services: lite, premium and deluxe. The cheapest version, lite, is a subscription service that costs $79 per month plus $385 for the device. Women can purchase the other two service levels for a one-time fee of $795 for premium and $1,299 for deluxe.

In the deluxe program, women receive the stick-on sensor and a hand-held reader to view data. They get an alert up to six days before ovulation and receive an initial review by fertility experts. They also get home pregnancy test kits, ongoing support from a personal fertility coach, and feedback after each fertility cycle.

The company plans to use the funds to expand product sales in the US and develop the next iteration of the DuoFertility tracker, which will offer smartphone connectivity and the ability to measure more metrics. One such metric is likely to be sleep analysis, according to Hooper.

"In order to develop DuoFertility for ovulation and fertility advice, we had to address factors that affect fertility, such as sleep disturbance," Hooper said. "We have CE marking for some aspects of sleep disturbance, and this is the area we will focus on next. As an outcomes-based company we see the potential to look other areas, for example working with groups such as pharma to address pain management, as it relates to sleep disturbance."

Hooper added that she sees other fertility apps, such as Glow, as potential partners moving forward.

DuoFertility, which commercially launched its FDA-cleared basal body temperature thermometer sensor in April 2012, has been working on fertility hardware since as early as 2011. Notably, the FDA clearance for this company specified that the device is not intended for use as a contraception device.