You are fertile for roughly 5 to 6 days each cycle. The best tracking methods are ovulation predictor kits (OPKs), basal body temperature, and cervical mucus monitoring. The highest conception rates come from intercourse on the day of ovulation and the two days before. See your GP after 12 months of trying (6 months if over 36).
Each cycle, one ovary releases a mature egg. The egg survives for 12 to 24 hours. Sperm can survive up to 5 days. Your fertile window starts about 5 days before ovulation and ends the day after. Ovulation typically occurs about 14 days before your next period starts, regardless of cycle length.
Ovulation predictor kits (OPKs). Urine strips that detect the LH surge 24 to 36 hours before ovulation. The most popular and reliable home method.
Basal body temperature (BBT). Your resting temperature rises by 0.2 to 0.5 degrees after ovulation. Useful for understanding your cycle pattern over months rather than predicting in real time.
Cervical mucus monitoring. As ovulation approaches, mucus becomes wet, slippery, and stretchy like raw egg white. Free and surprisingly effective.
Calendar method. Track your cycle length and count back 14 days from your expected period. Less precise but useful as a starting point.
Digital fertility monitors. Track both oestrogen and LH to identify a wider fertile window of 4 to 6 days.
The highest conception rates come from intercourse on the day of ovulation and the two days before. Every 1 to 2 days throughout your fertile window gives the best chance. Daily intercourse is fine and does not reduce sperm quality.
Some people notice a twinge on one side of the lower abdomen (mittelschmerz), increased libido, light spotting, breast tenderness, or heightened sense of smell. These are not reliable enough to use alone but can support other methods.
If your cycles are very irregular, conditions like PCOS may be affecting ovulation. A blood test measuring progesterone on day 21 can confirm whether ovulation is occurring.
NICE recommends seeing your GP after 12 months of trying (6 months if over 36). If you have known risk factors like irregular periods, PCOS, or endometriosis, there is no need to wait.
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