What is subfertility?

Medical terminology, especially in reproductive medicine can often be generally confusing or misleading. To understand what subfertility means, it's essential to define infertility. The clinical definition of infertility is currently "1 year of unwanted non-conception with unprotected intercourse in the fertile phase of the menstrual cycles."

Subfertility generally describes any form of reduced fertility. If you have subfertility, it will take longer to get pregnant and you will encounter a prolonged time period of trying but not conceiving. (Read our Guide to Infertility to find out more about it.)

What does it mean to be subfertile?

If you are subfertile, you still have a good chance of getting pregnant, even if you did not get pregnant the first or even second year. You don't necessarily need the diagnosis of subfertility to be subfertile, but the difference between infertility and subfertility is often that no matter your lifestyle, you cannot get pregnant on your own, however, the difference is that with subfertility, by improving your lifestyle, you can often improve your fertility. 

Infertility, as compared to subfertility, is diagnosed in someone who cannot get pregnant and for whom there is only a small chance of getting pregnant without medical intervention like medication or in-vitro fertilization (IVF). 

How is subfertility diagnosed?

The work-up for a subfertility diagnosis is not very different from the workup for a diagnosis of infertility, except that more attention is paid to a couple's lifestyle changes like smoking, weight, and diet.

  • A good medical history including a woman's weight
  • Review of a couple's diet
  • Menstrual abnormalities
  • Ovarian ultrasound
  • Semen analysis
  • Hormone testing in the female partner (eg Anti-Müllerian hormone and follicle-stimulating hormone)
  • Genetic testing in the male partner to rule out chromosomal disorders
  • Other diagnostic techniques (laparoscopic, hysteroscopic) may be used if indicated. 

What are the causes of subfertility?

The causes of subfertility are often not very different from those of infertility. As compared to infertility, there and certain choices in lifestyle that could be responsible for subfertility. After a diagnosis, many causes of subfertility can be treated and your chances of getting pregnant improve significantly.

Common causes of subfertility include:

  • Ovulation issues
  • Sperm abnormalities (eg, oligospermia; azoospermia)
  • Scarring around the fallopian tubes or ovaries
  • Endometriosis (minimal/mild or moderate/severe)
  • Uterine abnormalities
  • Advancing female age 
  • Fallopian tube problems (eg, adhesions, occlusion, partial tubal defects)
  • Unexplained subfertility.

What is the treatment for subfertility?

The main difference between couples that are subfertile and those that are infertile is in how the condition is treated. In subfertile couples, medical treatment may not be so immediate or aggressive, particularly in the early stage. Many causes of subfertility can be improved with lifestyle changes.

What are some lifestyle changes that help subfertility?

If you are found to be subfertile, addressing lifestyle changes first is easier to implement and offer fewer side effects and complications. Lifestyle changes may include:

  • Taking a supplement like FertilAid for Men or Women to  improve your chances of getting pregnant
  • Avoiding smoking which affects both male fertility and female fertility
  • Exercising moderately but not excessively (which can affect sperm count and a woman's menstrual cycle)
  • Monitoring your basal body temperature more closely
  • Adjusting the frequency of sexual intercourse (studies suggest too frequent sex may further reduce an already lower sperm count)
  • Weight reduction since obesity can affect fertility
  • Avoiding sexual lubricant that can affect sperm motility
  • Avoiding overheating the testes (through hot baths, saunas, or showers)
  • Changing from briefs to boxer to also prevent the overheating of the testes

What are some medical treatments for subfertility?

If lifestyle or other treatments don't improve subfertility, meaning if you did not get pregnant with these changes, then other medical treatments may be explored including fertility medications, in-vitro fertilization (IVF), surgery, or a combination of treatments.

What are the pregnancy outcomes with subfertility?

Several studies have shown that women with subfertility have worse pregnancy outcomes than fertile women. This is what a recent study published in Pediatric found: "Infants born to subfertile mothers were more likely to be preterm ... and have respiratory and gastrointestinal and/or nutritional conditions .. and  were at greater risk for congenital malformations and infectious diseases as well as cardiovascular and respiratory conditions.." "Compared with infants born to fertile mothers, infants of subfertile ..  mothers are at greater risk for adverse health outcomes at birth beyond prematurity."

Read More:
What Is Unexplained Infertility?
Top Causes of Infertility