About 80% of couples conceive within 6 months and 90% within 12 months. The per-cycle chance is about 20 to 25%. Age is the biggest factor, with fertility declining more noticeably after 35. See your GP after 12 months (6 months if over 36). Regular intercourse every 2 to 3 days gives the best chance.
For healthy couples having regular unprotected intercourse, about 30% conceive within the first month, 60% within 3 months, 80% within 6 months, 90% within 12 months, and 95% within 2 years. The per-cycle chance of conception is about 20 to 25%.
Even when everything goes right, the egg must be released at the right time, sperm must reach and fertilise it within 12 to 24 hours, the fertilised egg must implant, and the embryo must develop normally. Up to 50% of fertilised eggs do not implant or are lost very early.
Under 30, per-cycle rates are around 25 to 30%. At 35 to 40, rates drop to roughly 15 to 20%. Over 40, rates drop to around 5 to 10%. These are population averages, and individual fertility varies enormously.
Cycle regularity. Regular cycles suggest regular ovulation. Frequency of intercourse. Every 2 to 3 days gives the best chance. Body weight. BMI below 19 or above 30 can affect ovulation. Lifestyle factors. Smoking, heavy alcohol, high caffeine, and recreational drugs all reduce fertility. Underlying conditions. PCOS, endometriosis, thyroid disorders, and previous pelvic infections. Male factors. Heat exposure, certain medications, and lifestyle habits affect sperm quality.
NICE recommends after 12 months if under 36, or 6 months if 36 or over. If you have known risk factors, do not wait. Your GP can arrange blood tests and a semen analysis.
Position during intercourse does not affect conception rates. Lying with legs up has not been shown to help. Stress has not been conclusively shown to prevent conception in healthy, ovulating people.
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