World Health Organization statistics imply that infertility and sterility will be the third most serious diseases in the 21st century after cancer and cardiovascular diseases, according to a Life Times report.

Couples in China, the world's most populous nation, are having difficulty conceiving. Infertility in the country has risen from 12.5 to 15 percent, a reproductive health expert said.

Professor Lǚ Bodong, vice president of the Second Hospital of Zhenjiang Chinese Medical University in Hangzhou, east China's Zhejiang Province, attributes rising infertility rates to stressful and unhealthy lifestyles that include excessive drinking and smoking, over-indulgence, and also environmental problems, all of which are side effects of China's dramatic social and economic changes.

Professor Lǚraised three suggestions for avoiding infertility or sterility.

First, a harmonious sex life is the fundamental requirement for healthy babies. Both partners should enjoy the whole procreative process rather than viewing it as a burden, Lǚ said, adding that couples who have sex every two days are more likely to conceive.

Second, prospective mothers and fathers should choose a healthy lifestyle. Obesity, excessive drinking and smoking lower fertility. Fertility levels are lower after the age of 35 years, and multiple abortions are often the cause of miscarriages.

Finally, Lǚ also said that high temperatures lower sperm activity. "Soaking in a hot tub for long periods is bad for male fertility. After sitting for an hour, a man should take a 5 to 10 minute walk to lower the temperature surrounding the spermal sac."

Lǚ also advised couples to have regular check ups during pregnancy.