What Is the Cause of Subfertility?
Subfertility, often used interchangeably with infertility, refers to difficulty conceiving after 12 months of trying (or six months if over 35). Understanding the root causes can guide treatment and improve outcomes.
Let’s explore the most common factors contributing to subfertility and when to seek medical support.
1. Ovulation Problems (Hormonal Imbalance)
The leading cause of female subfertility—around 25% of cases—involves irregular or absent ovulation (anovulation) :contentReference[oaicite:2]{index=2}. Conditions such as polycystic ovary syndrome (PCOS), premature ovarian failure, thyroid disorders, and high prolactin levels disrupt hormone signals from the hypothalamus and pituitary :contentReference[oaicite:3]{index=3}.
2. Tubal or Pelvic Damage
Blockages, scarring, or damage to the fallopian tubes and pelvis account for 25–30% of subfertility cases :contentReference[oaicite:4]{index=4}. Common causes include pelvic inflammatory disease (often from chlamydia or gonorrhoea), endometriosis, past ectopic pregnancies, or abdominal surgeries :contentReference[oaicite:5]{index=5}.
3. Endometriosis
In 30–50% of women with subfertility, endometriosis plays a role. Ectopic endometrial tissue can provoke inflammation, adhesions, and impaired egg/sperm transport :contentReference[oaicite:6]{index=6}.
4. Uterine and Cervical Conditions
Uterine fibroids, polyps, scarring (e.g., Asherman’s syndrome), and cervical abnormalities can prevent implantation or hinder sperm passage :contentReference[oaicite:7]{index=7}.
5. Age & Poor Egg Quality or Ovarian Reserve
Fertility naturally declines after age 35 due to dwindling egg numbers and quality, which increases miscarriage risk :contentReference[oaicite:8]{index=8}. Premature ovarian insufficiency (before 40) affects about 1% of women :contentReference[oaicite:9]{index=9}.
6. Lifestyle & Environmental Factors
Smoking, obesity (BMI ≥30), being underweight, excessive exercise, and exposure to toxins (e.g., chemicals, radiation) impair hormonal health, egg quality, and reproductive function :contentReference[oaicite:10]{index=10}.
7. Genetic and Medical Conditions
- Genetic syndromes: Turner syndrome, chromosomal disorders causing ovarian failure or gonadal dysgenesis :contentReference[oaicite:11]{index=11}.
- Autoimmune or thyroid disease: Conditions like hyper/hypothyroidism, coeliac disease, or hyperprolactinaemia disrupt hormonal cycles :contentReference[oaicite:12]{index=12}.
- Cancer treatments: Chemotherapy or radiation may permanently damage ovarian function :contentReference[oaicite:13]{index=13}.
8. Unexplained Subfertility
In 5–10% of cases, all tests return normal—ovulation is regular, tubes are open, sperm is healthy yet conception doesn’t occur :contentReference[oaicite:14]{index=14}. Advanced investigations or assisted reproductive technologies may help.
When to See a Specialist
- No pregnancy after 12 months (or after 6 months if over 35).
- Known risk factors: irregular cycles, past infections, endometriosis, surgeries.
Links to Related Reading
FAQs
What is subfertility versus infertility?
Subfertility refers to a reduced chance of conceiving that may resolve with time or treatment; infertility typically means no pregnancy after 12 months of unprotected sex (<35) or 6 months (>35).
Can lifestyle changes help improve fertility?
Yes—quitting smoking, achieving a healthy BMI, reducing stress, and limiting toxin exposure can significantly enhance fertility :contentReference[oaicite:15]{index=15}.
Is unexplained subfertility common?
It affects 5–10% of couples. Many go on to conceive with help from fertility treatments like IVF or IUI :contentReference[oaicite:16]{index=16}.
When is assisted reproduction recommended?
After initial evaluation, fertility specialists may suggest ovulation induction, IUI, or IVF, depending on the cause, age, and prior outcomes.
Conclusion
Subfertility can have multiple overlapping causes—from hormonal imbalances to structural issues, lifestyle, genetics, and age. Identifying the underlying factors is vital to guide effective treatment and support conception journeys.
If you’d like helpful tips on ovulation tracking, lifestyle changes, or exploring fertility treatment options, I'd be glad to assist.