How Conception Works, Step by Step
Conception is a chain of events that has to happen in the right order and within a short window of time. Here's how it unfolds.
1. Ovulation
Around the middle of the cycle, a surge of luteinising hormone (LH) triggers an ovary to release a mature egg. The egg is picked up by the fallopian tube and survives for about 12 to 24 hours.
2. Fertilisation
If sperm are present in the fallopian tube, one may fertilise the egg. Sperm can survive for up to five days, so sex in the days before ovulation can still lead to fertilisation.
3. Early development
The fertilised egg divides as it travels toward the uterus over several days, becoming a blastocyst of around a hundred cells.
4. Implantation
Between about 6 and 12 days after ovulation, the blastocyst attaches to the lining of the uterus. It then starts producing hCG, the hormone pregnancy tests detect.
5. A positive test
hCG levels rise quickly, and most home tests can detect them from around the day of a missed period.
Ovulation Calculator: Predict ovulation days for your next three cycles.
Open the calculatorThis article is general information, not medical advice. Talk to a doctor or midwife about your own pregnancy or fertility.