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How Does Bodyweight Affect Fertility and IVF Outcome?

by Dr. Geoffrey Sher on April 3, 2016

The prevalence of obesity in Western societies is on the rise, which has a profound effect on the reproductive performance of women who are trying to have a baby. Recent evidence suggests that obesity in women of reproductive age is associated with decreased birth rates, increased miscarriage rates, lowered IVF success rates, higher rates of premature delivery and a marked increase in pregnancy complications. We use two parameters to measure height-weight relationship. The first is Body Mass Index (BMI) (the ratio of height to weight that is calculated by taking body weight in kg and dividing this by the square of height in meters. The second is the percentage contribution made by fat to overall body mass

BMI: A BMI of <20 is regarded as underweight; 20 – 25 is ideal/normal.  A BMI of >30 is definitively indicative of being overweight. A BMI of 30-40 is obese and > 40 is morbidly (dangerously) obese. The “ideal BMI” for fertility is 20-25. A BMI of<20 increases the risk of miscarriage. Women with a BMI of > 30 fertility often have a reduction in response to ovarian stimulation. BMI significantly impacts male fertility as well. Men with an increased BMI often experience significant sperm dysfunction.

Percentage Fat: The contribution of fat to body weight is also important. The normal contribution of fat to body mass in adult women is about 28%. Anything under 22% can result in dysfunctional or absent ovulation. Both diet and exercise modification can help regulate the percentage of body fat and BMI.

Simply stated, being overweight with a significantly elevated BMI and/or having a high percentage of body fat has a decidedly adverse effect on overall reproductive performance and fertility. When it comes to IVF in specific, while the results of several studies have been discordant, the general trend strongly suggests that women who are moderately overweight (BMI>25-30) and those who are obese (BMI>30) have worse IVF outcomes than the controls with a BMI <25. As alluded to above, it would appear that women with a BMI of >25 and especially those with a BMI of >30 exhibit a poorer ovarian response to fertility drugs (impaired follicle and embryo development with fewer blastocysts becoming available for transfer). These women also tend to have a reduced ability to implant transferred embryos into their uterine linings, perhaps due to reduced endometrial receptivity.  

Women with polycystic ovary syndrome (PCOS) often usually have BMI’s of >30.  In such women, the hormonal environment in the ovaries is known to adversely affect follicle and egg development, hindering fertility. Given that there is often no clear cut distinction between PCOS and other overweight women, it is possible that many of the factors that are believed to affect egg/embryo quality in PCOS might similarly affect egg development and endometrial receptivity in overweight women. Such factors could include increased production of luteinizing hormone (LH), hyperinsulinemia and increased production of ovarian male hormones (androgens such as testosterone.)  The link between increased LH and resulting increased production of ovarian androgens (mainly testosterone) and poor follicle and egg development is well established.  It is also well known that such hormonal changes can be transmitted to the adjacent uterus thereby adversely affecting endometrial development.  

Clearly the question arises as to whether the negative effect of an elevated BMI (>25) on general fertility potential and IVF outcome is due to compromised egg development, endometrial receptivity to the implanting embryo or both.  In my opinion, while a direct ovarian influence probably predominates, there is also likely to be an adverse influence on endometrial development.  This endometrial affect is commonly seen in PCOS women who, when they develop severe ovarian hyperstimulation on fertility drugs often have a very thin (< 8mm endometrium).

There is also the reality that it is often technically more difficult to perform a “smooth” and “flawless” embryo transfer in women who are overweight. This fact is especially true when it comes to those with a BMI of >30. Visualizing the cervix is much more difficult and the introduction of the embryo transfer catheter through the cervix, often difficult. Given that the efficiency by which ET is conducted, represents a rate-limiting determinant of IVF outcome, it follows that obese women tend to have poorer overall IVF outcomes.

Finally, it is important to emphasize that overweight women are at far greater risk during pregnancy than are women of normal body weight. As previously mentioned, the miscarriage rate is much higher, in addition to an incidence of diabetes, high blood pressure, preeclampsia, premature labor, surgically assisted deliveries, stillbirth and neonatal death. Maternal complications that occur after birth of the baby (i.e., infection, uterine post partum hemorrhage, etc. are also much more common.  Babies born to such mothers, are also at great risk of developing respiratory distress syndrome (RDS). This condition, which ordinarily only occurs in preterm babies, can also occur in the absence of prematurity in such cases. RDS is the most common reason for the newborn having to be admitted to a neonatal intensive care unit, and also the most common cause of death in the first week of life.  

The clinical significance of a growing population of overweight women is enormous because not only can this compromise their overall reproductive performance but it also compounds the risk of chronic medical conditions such as diabetes, coronary/cerebral/peripheral vascular disease and thus compromises life expectancy as well as the quality of life.  As such, being overweight represents an overall life hazard that should be addressed by the medical profession as well as by society as a whole.  The answer is surely not a simple one but the solution does not lie in dieting alone (which rarely is of sustained benefit). Instead it requires an overall modification in lifestyle.

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  • April - November 18, 2016 reply

    Hello Dr Sher,
    Thank you for your website. I dropped about 40 lbs this year to be at a better BMI (now between 24-25). I am six week pregnant. I had one healthy pregnancy go to 41 weeks followed by an unhealthy pregnancy that went to 31 weeks due to pre-e. I have had several chemical pregnancies over the past couple of years without a live birth between. I believe this was due to low progesterone based on my 24 day cycles (day 14 ovulation). The doctor is recommending baby aspirin, but I do not have any clotting disorders and did not have pre-e with my first pregnancy. Doctors said having it with second without having had it in first is exceedingly rare. I don’t expect to have it again! My second pregnancy was during an extremely stressful time in life that included no exercise, a poor diet, sleeping in a living room for months, and an international move. This time, I am in a stable place in life and am eating well and exercising. Can I use Ligusticum, the herb in place of baby aspirin? I’d rather not use anything at all since the research on pre-e and baby aspirin is so unconvincing. (My BIL is a pharmacist and he sent me the UpToDate article.) Thank you….

    Dr. Geoffrey Sher

    Dr. Geoffrey Sher - November 18, 2016 reply

    I am not familiar with Ligusticum, but I personally do not recommend aspirin to my patients.

    Geoff Sher

  • Lisa - June 3, 2016 reply

    Dear Dr Sher,

    I’ve just gone through a third IVF failure. The first was with my own eggs and we didn’t get as far as transfer because they didn’t develop well (I’m 44). The second two lots of IVF were with “perfect” 5-day blastocysts using donor eggs (the clinic I’m with doesn’t grade them – this was the only description they used). The first time one blast was transferred, and the procedure failed. The second time, both remaining blasts were transferred – and again it failed.

    A year ago I had a missed miscarriage, naturally conceived. I’ve also had two chemical pregnancies in the last two years.

    After the first IVF fail, the doctor said it was down to low egg quality – hence DEs.
    After the second he said it was because I only transferred one blast and that I may have clotting issues. I had a full screen for clotting – and it came back completely clear. So the doctor said it must be immunological and gave me intralipids immediately after the transfer. He said it the intralipids were “our last hope” – so I’m desperately sad now.

    I have three small fibroids outside of my uterus (none in the cavity – all under 3cm). Every blood test I have comes back perfectly healthy. Is it possible for this all to just come down to bad luck?

    Would I throwing my sanity and money away if I tried again?

    Thank you,
    L

    Dr. Geoffrey Sher

    Dr. Geoffrey Sher - June 3, 2016 reply

    I would advise testing for immune issues before treating. You at least have your blood tested for NK cell activity (using the K-562 target cell test) . If this is positive then testing can be extended. IL needs to be administered starting 10-14days PRIOR to the ET. Administration after the ET, will in my opinion not be ineffective. Small external fibroids should not be of consequence in my opinion.

    I strongly recommend that you visit http://www.DrGeoffreySherIVF.com. Then go to my Blog and access the “search bar”. Type in the titles of any/all of the articles listed below, one by one. “Click” and you will immediately be taken to those you select. Please also take the time to post any questions or comments with the full expectation that I will (as always) respond promptly.

    • Controlled Ovarian Stimulation (COS) for IVF: Selecting the ideal protocol
    • IVF: Factors Affecting Egg/Embryo “competency” during Controlled Ovarian Stimulation(COS)
    • The Fundamental Requirements For Achieving Optimal IVF Success
    • IVF Failure and Implantation Dysfunction:
    • The Role of Immunologic Implantation Dysfunction (IID) & Infertility (IID):PART 1-Background
    • Immunologic Implantation Dysfunction (IID) & Infertility (IID):PART 2- Making a Diagnosis
    • Immunologic Dysfunction (IID) & Infertility (IID):PART 3-Treatment
    • Thyroid autoantibodies and Immunologic Implantation Dysfunction (IID)
    • Immunologic Implantation Dysfunction: Importance of Meticulous Evaluation and Strategic Management:(Case Report
    • Intralipid and IVIG therapy: Understanding the Basis for its use in the Treatment of Immunologic Implantation Dysfunction (IID)
    • Natural Killer Cell Activation (NKa) and Immunologic Implantation Dysfunction in IVF: The Controversy!
    • Endometrial Thickness, Uterine Pathology and Immunologic Factors
    • Vaginally Administered Viagra is Often a Highly Effective Treatment to Help Thicken a Thin Uterine Lining
    • Traveling for IVF from Out of State/Country–
    • A personalized, stepwise approach to IVF
    • Uterine Fibroids and Fertility
    . Why did my IVF fail?

    Please call or email Julie Dahan, my patient concierge. She will guide you on how to set up an in-person or Skype consultation with me. You can reach Julie at on her cell phone or via email at any time:
    Julie Dahan
    • Email: Julied@sherivf.com
    • Phone: 702-533-2691
     800-780-7437

    Geoff Sher

    I also suggest that you access the 4th edition of my book ,”In Vitro Fertilization, the ART of Making Babies”. It is available as a down-load through http://www.Amazon.com or from most bookstores and public libraries.

  • TK - June 3, 2016 reply

    What do you recommend for patients with PCOS who struggle to loose weight, have high BMI, and are nearing advanced maternal age? While there are more risks associated with the procedure, birth, etc. would you still offer IVF treatment?

    Dr. Geoffrey Sher

    Dr. Geoffrey Sher - June 3, 2016 reply

    The prevalence of obesity in Western societies is on the rise. This has a profound effect on the reproductive performance of women who are trying to have a baby. Recent evidence suggests obesity in women of the reproductive age is associated with decreased birth rates, increased miscarriage rates, higher rates of premature delivery and a marked increase in pregnancy complications. We use two parameters to measure height-weight relationship. The first is Body Mass Index (BMI) (the ratio of height to weight that is calculated by taking body weight in kg and dividing this by the square of height in meters. The second is the percentage contribution made by fat to overall body mass
    BMI: A BMI of <20 is regarded as underweight; 20 - 25 is ideal/normal. A BMI of >30 is definitively indicative of being overweight. A BMI of 30-40 is obese and > 40 is morbidly (dangerously) obese. The “ideal BMI” for fertility is 20-25. A BMI of<20 increases the risk of miscarriage. Women with a BMI of > 30 fertility often have a reduction in response to ovarian stimulation. BMI significantly impacts male fertility as well. Men with an increased BMI often experience significant sperm dysfunction.
    Percentage Fat: The contribution of fat to body weight is also important. The normal contribution of fat to body mass in adult women is about 28%. Anything under 22% can result in dysfunctional or absent ovulation. Both diet and exercise modification can help regulate the percentage of body fat and BMI.
    Simply stated, being overweight with a significantly elevated BMI and or having a high percentage of body fat has a decidedly adverse effect on overall reproductive performance. And when it comes to IVF in specific, while the results of several studies have in some cases have been discordant the general trend strongly suggests that women who are moderately overweight (BMI>25-30) and those who are obese (BMI>30) have poorer IVF outcomes than do controls with a BMI <25. As alluded to above, it would appear that women with a BMI of >25 and especially those with a BMI of >30 exhibit a poorer ovarian response to fertility drugs (impaired follicle and embryo development with fewer blastocysts becoming available for transfer). They also tend to have a reduced ability to implant transferred embryos into their uterine linings (perhaps due to reduced endometrial receptivity).
    Women with polycystic ovary syndrome (PCOS) often usually have BMI’s of >30. In such women, the hormonal environment in the ovaries is known to adversely affect follicle and egg development. Given that there is often no clear cut distinction between PCOS and other overweight women, it is possible that many of the factors that are believed to affect egg/embryo quality in PCOS might similarly affect egg development and endometrial receptivity in overweight women. Such factors could include increased production of luteinizing hormone (LH), hyperinsulinemia and increased production of ovarian male hormones (androgens such as testosterone). The link between increased LH and resulting increased production of ovarian androgens (mainly testosterone) and poor follicle and egg development is well established. It is also well known that such hormonal changes can be transmitted to the adjacent uterus thereby adversely affecting endometrial development.
    Clearly the question arises as to whether the negative effect of an elevated BMI (>25) on general fertility potential and IVF outcome is due to compromised egg development, endometrial receptivity to the implanting embryo or both. In my opinion, while a direct ovarian influence probably predominates, there is also likely to be an adverse influence on endometrial development. This endometrial affect is commonly seen in PCOS women who, when they develop severe ovarian hyperstimulation on fertility drugs often have a very thin (< 8mm endometrium). Then there is the reality that it is often technically more difficult to perform a “smooth” and “flawless) embryo transfer in women who are overweight. This is especially true when it comes to those with a BMI of >30. Visualizing the cervix is much more difficult and the introduction of the embryo transfer catheter through the cervix, often difficult. Given that the efficiency by which ET is conducted, represents a rate-limiting determinant of IVF outcome, kit follows that obese women tend to have poorer overall IVF outcomes.

    Finally, it is important to emphasize that overweight women are at far greater risk during pregnancy than are women of normal body weight. As previously mentioned, the miscarriage rate is much higher. So is the incidence of diabetes, high blood pressure, preeclampsia, premature labor, surgically assisted deliveries, stillbirth and neonatal death. Maternal complications that occur after birth of the baby (i.e., infection, uterine post partum hemorrhage, etc. are also much more common. Babies born to such mothers, are also at great risk of developing respiratory distress syndrome (RDS). This condition which ordinarily only occurs in preterm babies can also occur in the absence of prematurity in such cases. RDS is the commonest reason for the newborn having to be admitted to a neonatal intensive care unit and also the commonest cause of death in the first week of life.

    The clinical significance of a growing population of overweight women is enormous because not only can this compromise their overall reproductive performance but it also compounds the risk of chronic medical conditions such as diabetes, coronary/cerebral/peripheral vascular disease and thus compromises life expectancy as well as the quality of life. As such, being overweight represents an overall life hazard that should be addressed by the medical profession as well as by society as a whole. The answer is surely not a simple one but the solution does not lie in dieting alone (which rarely is of sustained benefit). Instead it requires an overall modification in lifestyle.

    The only way to lose weight is by cutting down caloric intake anf burning more calories by increasing activity/exercise.

    Good luck!

    Geoff Sher

  • Katy - April 10, 2016 reply

    How significant is being slightly underweight, in your opinion? I have worked hard at putting on weight, bringing my BMI up from 17.5 to 19 – in the UK this is within healthy range, and within the range the NHS considers healthy for IVF. In your opinion, is a BMI of 19 likely to be a problem? (I am having IVF due to DOR, but do not have any ovulatory dysfunction, although I do have naturally thin endometrial lining, which does respond well to oestrogen)

    Dr. Geoffrey Sher

    Dr. Geoffrey Sher - April 10, 2016 reply

    I do not think a BMI of 19 is a problem, provided you are ovulating and have a normal ovarian reserve (AMH)!

    Geoff Sher

    Katy - April 10, 2016 reply

    I have a horrific AMH (1.5 pmol/l) which you advised in your v helpful comment on the open forum was likely a lab error, as I got 17 eggs & 5 blasts from my recent cycle. It was measured 3 times in 3 different months at two different labs, so I appear to have Schrodinger’s ovarian reserve – simultaneously severe DOR and NOT severe DOR (!)

    What are the implications of a low BMI for low ovarian reserve?

    Thank you in advance, your advice is very much appreciated

    Dr. Geoffrey Sher

    Dr. Geoffrey Sher - April 10, 2016 reply

    This is an unusual response for such a low AMH and high basal FSH. But let’s hope it was not just a freakish one time occurence.

    Your lowish BMI could, but likely will not affect ovarian reserve.

    Geoff Sher

    Good luck!

    Geoff Sher

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