Getting pregnant is like playing the lottery. You play against all odds and hope for the jackpot, because conception and pregnancy still resemble a miracle.
In order for a new human being to come into existence, sperm cells must be released into the vagina to find their way through the cervix into the uterus and finally the fallopian tubes, where they meet the ovum, which matures for days and can only be fertilised within a very short time frame. Then the fertilised ovum needs to divide itself, nest, further divide and grow into an embryo and later into a foetus. All in all, getting pregnant is less of a strategy game and more like a wheel of fortune, or Russian roulette with a happy ending. What exactly are the chances of getting pregnant?
On the one hand, numbers don’t lie, but at the same time, you shouldn’t trust statistics that you haven’t falsified yourself. Be that as it may, mathematical probabilities paradoxically convey the feeling of security, and in recent years the topic of conception probability has increasingly sparked the interest of scholars and scientists alike.
Recent studies have attempted to find data for the moment with the highest probability for conception within the fertile window. Amongst other things, it could be shown that the duration of the fertile window in couples with average fertility is not fixed with six days but varies considerably from individual to individual (compared to other couples) and on the intrapersonal level (related to the respective couple, i.e. from cycle to cycle). In subfertile couples, the variation is even greater, and the fertility window is shorter compared to higher fertility couples.
The length of the fertile window is also related to the rate at which a woman becomes pregnant. The longer the fertile days, the more likely it is that a pregnancy will occur.
In the respective studies, different parameters were used to calculate the conception probability and therefore differ greatly in their results. For example, in the studies with ovulation as the reference marker, the highest conception probability is given with 33% on the day of ovulation (German database) and with 36% two days before ovulation as well as on the day of ovulation (US database). Another American study lists the day before ovulation as the one with the highest probability of 30%.
Ultimately, such statistical models are merely an approximation, and the results should neither unsettle nor be considered absolute. Nevertheless, they are interesting and provide a basis for further scientific debate.