Why Am I Not Getting Pregnant? The 12 Most Common Reasons

Why Am I Not Getting Pregnant? The 12 Most Common Reasons

In most cases where couples struggle to conceive, there is an identifiable cause — and most causes are treatable. Here are the 12 most common.

1. Missing the Fertile Window

The most overlooked cause. The fertile window is only 6 days per cycle. In a natural cycle, ovulation can fall anywhere from day 11 to day 21 — relying on "day 14" is unreliable for most women. Couples who consistently miss the window will not conceive even with perfect fertility. Use LH ovulation test kits.

2. Ovulation Problems

Ovulation disorders cause approximately 25–30% of female infertility. PCOS is the most common cause — affecting 6–12% of reproductive-age women. Others include hypothalamic amenorrhoea (from very low weight or extreme exercise), thyroid disorders, and elevated prolactin. Signs: irregular cycles (shorter than 21 or longer than 35 days), absent periods, or no positive OPK reading.

3. Diminished Ovarian Reserve

Egg quality declines with age — most steeply after 37. The egg aneuploidy (chromosomal error) rate rises from ~25% at age 30 to ~75% at age 40. Even with regular ovulation, most eggs in older women are chromosomally abnormal. Diagnosed with AMH blood test.

4. Blocked Fallopian Tubes

Tubal damage from pelvic inflammatory disease (PID), chlamydia, endometriosis, prior surgery, or ectopic pregnancy blocks the egg and sperm from meeting. Blocked tubes produce no symptoms and cannot be detected by blood tests — require HyCoSy, HSG, or laparoscopy.

5. Endometriosis

Found in 25–50% of women investigated for infertility. Causes infertility through inflammation, ovarian damage (endometriomas), impaired tubal function, and reduced endometrial receptivity. Average diagnostic delay: 7–10 years. Many women with endometriosis have no pain.

6. Uterine Abnormalities

Submucous fibroids, endometrial polyps, uterine septum, and Asherman's syndrome all impair implantation. Cannot be detected on standard ultrasound — require saline infusion sonography (SIS) or hysteroscopy.

7. Male Factor Infertility

Male factor contributes to 40–50% of all infertility. A healthy-appearing man can have severely abnormal sperm. The only way to know is a semen analysis — which should be done at the start of any fertility evaluation, not saved for later.

8. Age-Related Egg Quality Decline

Monthly conception rates fall from ~20% at age 32 to ~5% at age 40. This is not because ovulation stops — it is because most eggs in older women are chromosomally abnormal and result in failed fertilisation, failed implantation, or early miscarriage.

9. Thyroid Disease

Subclinical hypothyroidism (TSH >2.5 mIU/L) and positive thyroid antibodies significantly increase miscarriage risk. A TSH blood test identifies this — the most commonly missed, most easily treatable cause of infertility and recurrent miscarriage.

10. Sperm DNA Fragmentation

A normal semen analysis does not test DNA integrity. High sperm DNA fragmentation (>25% DFI) causes failed fertilisation, poor embryo development, and early pregnancy loss even when sperm counts look normal. Separate test required.

11. Unexplained Infertility

After a complete workup, 15–30% of couples have no identified cause. Hidden causes include chronic endometritis, minimal endometriosis, poor egg quality, and sperm DNA fragmentation. IVF is both treatment and diagnosis — fertilisation failure in IVF reveals issues no pre-IVF test can detect.

12. Luteal Phase Deficiency / Antiphospholipid Syndrome

Insufficient progesterone after ovulation prevents endometrial preparation for implantation. Antiphospholipid syndrome (APS) causes recurrent early loss through placental thrombosis — found in 15% of recurrent miscarriage cases; treated with aspirin + heparin.

Reference: ASRM Practice Committee — Fertility Evaluation of Infertile Women, 2021. ESHRE Guideline — Female Infertility, 2023.