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Predicting Your Chance of Getting Pregnant from an IVF Cycle: Other Medical Factors
a blog by Mylene Yao, M.D., CEO and Co-Founder, Univfy, Inc., May 13, 2013
In the first two posts, we looked at ovarian factors and sperm factors that impact your chance of becoming pregnant with IVF. In this post, we’ll examine other non-reproductive system fertility factors that can affect your personal probability of getting pregnant with IVF.
Your body mass index (BMI) is a calculation of your weight and height. Although many research studies report that a BMI value either above or below the normal range (18.5-24.9) is sub-optimal for fertility, the exact impact of your BMI on your IVF success is specific to how you fare on other factors that we discussed previously (see previous posts). If your BMI is over 24.9, there’s no need to panic. Overall, it may have less impact than suggested by research that is based on group averages, especially if the complete reproductive profiles of patients have not been analyzed.
Some general concepts hold true. Having an abnormally low BMI (being underweight) is a negative factor, because your body may not have the required energy reserves for the extra metabolic needs of a healthy pregnancy. If you have a high BMI and are overweight or obese, you may develop a hormonal imbalance that interferes with normal ovulation and egg maturation-- two negatives for fertility.
Obesity may reduce the number of eggs your doctor can retrieve during your egg retrieval for technical reasons. In an obese patient, the ovaries may be located up higher into the abdomen, making it more difficult to reach every possible egg with the retrieval needle. Likewise, the ultrasound image of the ovaries may be blurry due to extra fatty tissue surrounding the ovaries. Both of these factors together may reduce the number of mature eggs collected at retrieval, which reduces the number of embryos for transfer, ultimately reducing your chance of pregnancy with IVF.
Chronic health conditions, such as diabetes, thyroid problems, or cardiac disease, can further affect your fertility. Smoking has a negative impact, because it reduces the quality of the eggs you produce, making them more resistant to fertilization. For example, a young woman with good ovarian reserve test results, no chronic medical conditions, a normal BMI, and a partner with good sperm quality may have a lower probability of success with IVF than expected if she smokes, based on the relative impact of each of these factors on her overall fertility.
The benefit of using statistical modeling for fertility factors is that the fertility factors you have (your ovarian reserve, your response to gonadotropins, your previous IVF history, your partner’s sperm count, your BMI and your history of smoking) can all be analyzed together to create your personal probability of pregnancy with IVF. What this means is that using analysis that is primarily based on age and/or just one or two other factors to predict whether IVF may work for you can under-or overestimate your chances, compared to a more personalized and comprehensive analysis of your unique combination of fertility factors. IVF prediction test results can add an important piece of the puzzle to help your doctor when counseling you about whether to start, continue or stop IVF treatments.