What Is Subfertility?

Medically Reviewed by Poonam Sachdev on November 11, 2022
5 min read

Successful pregnancy requires a woman to produce a healthy egg, a man to produce healthy sperm, the sperm to fertilize the egg, and the fertilized egg to settle in the uterus and grow into a baby. A disorder affecting any of these requirements can cause subfertility.

Subfertility is reduced fertility with a prolonged time of unwanted nonconception and includes many reversible causes. Subfertility affects more than 48 million women worldwide. One couple in seven has difficulty conceiving a baby.

Subfertility is difficulty in achieving pregnancy. Couples who have regular sex without using any protection and don't get pregnant are considered subfertile. Couples who have sex every two or three days have an 84% chance of conception in a year. Even those who have been trying for three years without success have a 1 in 4 chance of getting pregnant naturally in the next year.

Some women are able to get pregnant but can't carry the baby to term. This is called impaired fecundity. Women unable to get pregnant or complete their pregnancy make up 26% of heterosexual women.

Infertility is an absolute inability to conceive. One of the partners has a condition that makes it impossible to have a pregnancy. Subfertility is a situation where the couple has difficulty getting pregnant. It may also be caused by medical problems like sperm deficiencies or tubal diseases.

While people with infertility can never get pregnant without medical help, couples with subfertility may sometimes achieve a pregnancy in a natural way.

Several disorders can cause subfertility, and it takes diligent examination and diagnostic testing to find the cause in a couple. About a third of cases are due to a female factor, another third due to a male factor, and the other third due to unknown reasons.

Several factors can cause subfertility among women:

Ovulation problems: The absence of release of an egg from the ovaries during the menstrual cycle. Some causes include thyroid disorders, polycystic ovary syndrome (PCOS), and premature ovarian failure.

Cervical mucus problems: Thick mucus at the cervix (neck) of the uterus that can make it impossible for sperm to get through and reach the egg,

Prior surgery: Damage to the fallopian tubes or cervix of the uterus.

Endometriosis: A condition in which the lining of the uterus (the endometrium) is abnormally present outside the uterus. This can damage the ovaries or fallopian tubes. 

Fibroids: Noncancerous tumors in the uterus. Fibroids can block a fallopian tube or prevent a fertilized egg from settling in the uterus.

Pelvic inflammatory disease: Infection of the uterus, fallopian tubes, and ovaries. Scarring in the fallopian tubes makes it impassable for sperm.

Medicines: Chemotherapy, anti-inflammatory drugs, medications for mental health disorders, and spironolactone.

Prior sterilization: This surgery is usually irreversible.

If you're a man, your doctor will examine you and ask for a semen analysis to find the cause of subfertility. An expert will determine the number of sperms, their shape, and their movement. Doctors may need to do tests for hormones, gene studies, and other investigations to find the cause, which can include:

Injury to the testes.

Varicocele: A condition of large veins in the scrotum.

Substance abuse: Alcohol, drugs, tobacco, or anabolic steroids.

Cancer treatment.

Medical conditions: Infections, autoimmune disorders, diabetes, cystic fibrosis, and others. 

Hormonal disorders: Hypothalamus or pituitary disorders, glucocorticoid medications, Cushing's syndrome, or hormone therapy.

Genetic disorders: Y-chromosome microdeletion, Klinefelter syndrome, or myotonic dystrophy.

When you should see a fertility specialist depends on your age and other circumstances. Subfertility testing can be expensive, exhausting, and emotionally draining. If you're young, you shouldn't jump into the program quickly. Sometimes, a few more months of trying does it. At later ages, though, a little more urgency is appropriate:

  • Failure to conceive after frequent sex without any protection for a year, at any age, is a cause for concern.
  • Women over 35 should consider testing after six months. This is because fertility declines after this age.
  • If you're a woman over 40, you could think about testing earlier.
  • Same-sex couples unable to get pregnant after six cycles of artificial insemination should consult a fertility specialist.

Fertility testing takes a lot of work and time. It's best for both partners to visit the specialist together so that the investigation of both can proceed at once, saving some time. Be prepared to support each other, answer questions about your sex life, and undergo a series of tests until the doctor finds the cause. Your doctor may ask for blood tests, tests for sexually transmitted diseases, semen analysis, ultrasound, X-rays, laparoscopy, and other procedures.

If your doctor finds a cause for subfertility, they will treat it. For example, they will stop or change any drugs causing it. A surgeon can operate on a varicocele to remove it. Such treatment may lead to a natural pregnancy. But if the cause is not treatable or no cause is found, your doctor will decide on a suitable treatment. Some of the medications used for the treatment of subfertility include:

Clomiphene: If you're not producing eggs regularly, this medication can stimulate your ovaries.

Tamoxifen: This is an alternative to clomiphene. 

Letrozole: This medication lowers progesterone levels and provokes the secretion of follicle-stimulating hormone (FSH), increasing egg production. 

Metformin: If you have insulin resistance or diabetes and PCOS, your doctor may prescribe this drug, sometimes with clomiphene.

Bromocriptine or cabergoline: If your doctor finds your ovulation problems are because of high prolactin levels, they will prescribe one of these medications.

Gonadotropins: Human menopausal gonadotropin (hMG) and FSH stimulate the ovaries to produce eggs. 

Gonadotropin-releasing hormone: This hormone stimulates the ovaries to produce eggs.

This treatment is also called artificial insemination. It may be combined with medications that stimulate ovulation. The male partner provides a sample of semen, which is washed and filtered in a laboratory. The concentrated sperm sample is inserted into the uterus using a speculum and catheter. The procedure is almost painless and takes 10 minutes.

IUI is helpful under these conditions:

  • No identified cause for subfertility
  • Mild male factor subfertility
  • Inability to have vaginal sex because of physical disability or psychosexual problems
  • One partner with human immunodeficiency virus (HIV), making it dangerous to have unprotected sex

These are advanced techniques to help couples with subfertility have a baby. ART involves handling either eggs or embryos outside the body. There are several types.

In vitro fertilization (IVF). An egg is removed from the ovary and fertilized with sperm in the laboratory. The fertilized egg is placed in the uterus to settle and grow into a baby. IVF is the most frequent type of ART. Success depends on the age of the woman partner and varies from 32% for women under 35 to less than 5% for women over 42.

Intracytoplasmic sperm injection (ICSI). This is valuable for male factor infertility. A doctor injects a single sperm into a mature egg.

Zygote intrafallopian transfer (ZIFT) or gamete intrafallopian transfer (GIFT). This is rarely used in the U.S. today. Gametes or fertilized eggs are placed in the fallopian tube.

Egg and sperm donation. You may need this if you're not producing healthy sperm or eggs.

Embryo donation. These are additional, unused embryos created by a couple during subfertility treatment. They can be donated to other subfertile couples. The baby will not be genetically related to either parent.