The live birth rate in IVF, which is the percentage of mothers who eventually succeed in delivering a live newborn, is currently around 30% worldwide, meaning that out of 100 embryo transfer cycles, 30 cycles of mothers deliver a healthy baby. This is the indicator we are most interested in for infertile couples to obtain a healthy baby. So, by what indicators can live birth rates be predicted? Scholars from Sweden developed a model to predict live birth rates by collecting and analyzing treatment data (more than 100 parameters) from 5,699 couples with 8,451 IVF/ICSI cycles who underwent IVF treatment from 1999 to 2014. These female patients were 19 to 43 years old, underwent elective single embryo transfer, and many of these couples underwent multiple IVF treatments. By building a mathematical model, the scholars found that embryo score, treatment history, ovarian sensitivity index (number of oocytes/total dose of FSH used), female age, cause of infertility, endometrial thickness and female height were all independent predictors of live births. Yes, it is surprising that female height was also an independent predictor of live birth rate. In this study, the live birth rate was the primary observation for a single embryo transfer, so that the final outcome of each embryo could be known. The embryo score corresponds well to the outcome, and the higher the score, the better the developmental potential of the embryo and the higher the live birth rate. Treatment history, i.e. the number of IVF treatments done. An increase in the number of treatment failures may indicate a decrease in the live birth rate. Ovarian sensitivity index, which is the ratio of the number of eggs obtained to the dose of FSH used. Women who can obtain more eggs with a lower dose of FSH are usually those with better ovarian reserve and better ovarian response, and they tend to have higher live birth rates. The age of the woman is a well-established predictor of clinical pregnancy rate or live birth rate, which decreases significantly in women over 37 years of age. Causes of infertility, using tubal factors as a control group, found that ovulation disorders, endometriosis, male factors, and unexplained infertility did not affect live birth rates, but this result is still controversial. Endometrial thickness, >10 mm results in higher live birth rates, while <7 mm decreases live birth rates. (In some patients with thin endometrium, when it is not possible to improve the endometrial thickness, our center's experience proves that improving endometrial blood flow improves pregnancy and live birth rates.) One of the surprises brought by this study was that women's height was also an independent predictor of live birth rate. Previous findings have also suggested a (positive) correlation between female height and heterozygotic twins (both spontaneous pregnancies and IVF treatment) and a (poor) correlation between female height and preterm birth. Human height has steadily increased over the past centuries, which is thought to be the result of improved health and nutrition. It can be speculated that reproductively involved growth factors may also be involved in body growth. Further validation of the relationship between height and live birth rate in women after IVF/ICSI is needed in future studies. This is a single-center study and limited to second day single embryo transfer and cannot be generalized to all reproductive centers, but it is informative for physicians to patients. After reading the above, perhaps you can better understand why we all have different chances of success, because there are so many factors that affect success, and those with advantages are more likely to succeed, while those who lack advantages may need to pay more to achieve success.