MADRID- Buyout funds including KKR and Permira are lining up preliminary bids worth up to 2 billion euros ($2.24 billion) for Spain's IVI-RMA, sources told Reuters, amid growing demand for companies offering fertility treatment in Europe.

Fertility companies are attracting growing interest from private equity and other buyers as both the number of couples with fertility problems and the age of first time mothers rises.

Bain Capital, CVC Capital Partners, Carlyle and PAI Partners are also looking to submit offers for a controlling stake in the Spanish group ahead of a deadline for non-binding offers in late February, the sources said on condition of anonymity.

Valencia-based IVI-RMA, KKR, Carlyle, Permira and PAI declined to comment. Bain Capital and CVC were not immediately available to comment.

Spain is one of Europe's largest markets for in-vitro fertilization (IVF) and is expected to be the main contributor to the region's overall IVF revenues, with a compound average growth rate (CAGR) of 7.21% due to an increase in fertility tourism and the high success rates of treatments, a study by Market Data Forecast said.

IVI-RMA was formed in 2017 when a group of doctors and investors from Spain's eastern region of Valencia merged IVI with U.S. rival RMANJ. IVI's investors control 70% of the combined entity, while RMANJ has the balance.

The firm, which manages more than 75 clinics and 28 labs in nine countries, could be valued at between 16 and 17 times its core earnings of 120 million euros, one of the sources said.

The World Health Organization (WHO) estimates that 15% of reproductive-aged couples worldwide are affected by infertility, while Eurostat found that the average age of women giving birth to their first child in the EU was 29.4 years in 2019.

With plentiful cash available, private equity firms have moved to invest in the sector, with KKR buying GeneraLife, one of Europe's largest fertility clinic groups, in November.

EQT, meanwhile, sold its reproductive genetic testing services provider Igenomix to Swedish medical technology group Vitrolife in a deal worth 1.25 billion euros. ($1 = 0.8949 euros)

(Reporting by Andres Gonzalez, editing by Pamela Barbaglia and Alexander Smith) ((andres.gonzalez@thomsonreuters.com; 0034 647 69 49 89; Reuters Messaging: andres.gonzalez.thomsonreuters.com@reuters.net))