Becoming pregnant is such a complex process that there is a much greater probability of not becoming pregnant during a menstrual cycle than becoming pregnant.

Even for fertile couple having regular sex, i.e. two or three times a week without any contraception, the chance of the female becoming pregnant within one menstrual cycle is not more than 25%.

What is subfertility?

Subfertility means difficulties in becoming pregnant despite having regular sex when not using contraception after one year.

Subfertility is a common condition, affecting 1 in every 6 couples.

Causes of subfertility

There are various causes of subfertility, both in females and in males. Female and male factors each account for about 30% of subfertility cases respectively and the remaining 40% is either a joint problem or has no identified cause (unexplained subfertility). It has to be emphasised that a combination of female and male problems frequently co-exists and so the couple should be involved in the process of evaluation.

Subfertility in women

  • Age: Natural fertility decreases with increasing female age, in particularly after mid-thirties
  • Medical conditions include:
    • Ovulation problems e.g. Polycystic ovary syndrome, early menopause, thyroid problems, etc.
    • Pelvic adhesions or blockage of fallopian tubes resulting from endometriosis, pelvic infection, pelvic operation, or structural abnormalities of the uterus

Subfertility in men

  • Unfavourable factors that affect production or transportation of sperm, e.g. smoking, alcohol drinking, undescended testis, varicose vein in the scrotum (varicocele), or damage of genital tract from previous infection or operation

Unexplained subfertility

  • If a detailed history and physical examination followed by investigations still fail to find out a cause, it is named as 'unexplained subfertility'
  • In unexplained subfertility, two main factors affecting the chance of pregnancy are the duration of subfertility and the women's age. The natural ability to get pregnant will decrease in those women who are in advanced age or in couples with subfertility for more than three years

General advice

  • Maintain regular sexual intercourse, say 2 to 3 times a week, with a slight increase in the frequency (such as once every 2 days) around the time of ovulation
  • Smoking, alcohol drinking and drug abuse should be avoided by the couple
  • Women who are significantly overweight may have difficulty in getting pregnant and increased risk of miscarriages. On the other hand, those who are significantly underweight may have menstrual dysfunction and may not ovulate. Therefore, they should maintain an optimal body weight
  • Well-balanced diet, regular physical activities and managing stress are important for optimal reproductive function
  • Women who are not sure about their immunity to rubella should consult their family doctors to assess the need for rubella vaccination before pregnancy

Can more frequent sexual intercourse help to increase chance of pregnancy?

  • Too frequent sexual intercourse, say once every night, may result in decrease in the number of sperms in the semen. On the other hand, too infrequent sexual intercourse, say less than once per week, will lead to immotile sperms in the semen. Both conditions may adversely reduce the chance of pregnancy

Couples with the followings should consider earlier medical consultation:

  • For female
    • Age at late thirties
    • History of three or more miscarriages
    • Long and irregular menstrual cycle
    • Menstrual cycle of three weeks’ interval or less
    • Pain during menstruation or sexual intercourse
    • History of endometriosis
    • History of pelvic infection
    • History of pelvic or ovarian operation
  • For male
    • Had mumps in childhood
    • Had erectile or ejaculatory problem
    • History of prostate infection
    • History of undescended testis
    • History of varicocele

Subfertility is not the same as sterile. Some conditions are easier to treat than the others. Therefore, couples are encouraged to seek professional advice promptly.

Where to get help?

The basic subfertility evaluation and treatment can be carried out by the gynaecologists in the Hospital Authority, Family Planning Association or the private sectors. However, if there is no identifiable cause for subfertility or if the couple does not conceive after treatment within a given time, they may be referred to a specialist in subfertility or an Assisted Reproductive Unit of public or private hospitals.

Treatment success rate decreases remarkably with increasing female age. Even with the use of advanced assisted reproductive technologies, the success rate for women aged over 45 is more or less equal to zero. Therefore, subfertile couples should seek professional advice promptly.

Other choices

If all treatments are failed or the couples are actually not suitable for treatment, they have to decide whether or not to accept to be childless, or consider adoption. They are in charge of the situation, and they should be prepared to accept the possible consequences of different options.


The couple can explore their own personal interests and common interests with the spouse, expand their social circles and strengthen their relationships with other family members and friends.


If the couples are mentally and physically healthy, ready to make a life-long commitment to adopt a child and to take up parental responsibilities, they may consider to apply for adoption. Further information can be obtained from the Adoption Unit of Social Welfare Department (

(Content revised 05/2016)