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Study Shows Increased Infertility Risk for a BMI Over 30

Study Shows Increased Infertility Risk for a BMI Over 30

We all know that obesity can lead to long-term chronic health problems, but did you know that it may also lead to infertility? Research has shown not only a link between obesity and anovulation, but there is an infertility risk for obese women who have regular ovulation as well.

Jan Willian Van der Steeg, MD published his findings in the December 2007 issue of the journal Human Reproduction. He and his colleagues followed 3,029 couples having trouble conceiving after a year or more of trying. All of the men had normal semen analysis. All of the women were ovulating and had at least 1 functional fallopian tube. All couples were monitored until pregnancy was achieved or fertility treatments began.

The women were noted as underweight, normal weight, overweight or obese, based on their Body Mass Index (BMI). 86% of participants were normal weight or overweight. 10% were obese. To understand BMI, let me give you an example. A woman who is 5’7” tall, who weighs 140 lbs. has a BMI of 22 and is considered weight appropriate. A woman who is 5’7” tall, who weighs 170 lbs. has a BMI 0f 27, she is considered overweight. Now if the woman is 5’7” tall and weighs 190 lbs. or more, she is considered obese with a BMI of 31 or higher.

Women with a BMI of 35 were 26% less likely to naturally conceive on their own, compared to overweight to normal weight women. Women with a BMI of 40 or more, were 46% less likely to conceive on their own. Findings showed that the obese women had more trouble conceiving than the other group of women. Despite Van der Steeg’s findings, he and his colleagues could not find an explanation as to why women who are ovulating regularly, despite being obese, have a harder time conceiving on their own. It has been suggested that high insulin levels affect the hormone leptin which, in turn, may prevent fertilization of the egg, though he is not for sure.

Increased Infertility Risk for Obese Men
Obesity in men lowers testosterone levels. Chronic low levels of testosterone affect how the testes function, which causes all hormones produced by them to be out of balance. This may also lead to lowered function of producing mature sperm. Over time, this may lead to male infertility. Research shows elevated levels of estrogen in obese men. The sperm of obese men are often abnormal; this increases risk for miscarriage and chromosomal defects in a developing embryo. Obese men also often have sexual dysfunction.

New Research Shows Link Between Pituitary Function and Obesity-Related Infertility…
Doctor’s used to think that infertility in relation to obesity was due to chronically high insulin levels present in the body. It was thought that the high insulin levels over time made the muscles and other tissues unaffected by the hormone’s signals. Researchers at Johns Hopkins University, led by Andrew Wolfe, discovered that despite chronically high insulin levels due to obesity in mice, the pituitary gland still is receptive to the signal of insulin, and continues to be signaled to release fertility hormones. This leads to an overabundance of fertility hormones, which disrupts the natural function of the reproductive system, and consequently leads to infertility. No human testing has been done to see if this is in fact the case for humans, but it completely shocked the doctors. The discovery firmly ties metabolism to fertility, which is forcing doctors to look at treating high insulin levels, associated with fertility issues, in a new way. They believe this will be extremely helpful for treating PCOS in the future.

What You Can Do Today To Increase Fertility

Lifestyle and Diet Changes
If you think obesity may be a factor in your struggles to get pregnant, or carry to term, first chart your BMI. Finding out what your BMI is, may help you to determine if you are considered obese for your height and weight. Make a goal to reduce your BMI to lower than 30, to start with.

  • Take a look at your daily eating habits. Keep a journal of everything you eat in a day, this will help you to gain perspective on what you are eating, and how often you are eating.
  • Change how you eat and what you are eating. Make a commitment to long-term changes in your relationship to food. Seek the guidance of a nutritionist if necessary. You cannot lose body fat for good, or maintain a healthy weight and lifestyle, by only committing to short-term changes. These must be permanent life changes.
  • Get moving! Being obese or even overweight can make you feel like you have gotten to a place that seems impossible to exercise. Start off slowly. The best exercise you can do, which is also the easiest, is walk. That’s it, begin to go for a 30-minute walk, 5-6 times a week. As you build up stamina, walk farther and faster each day. As you begin to lose weight, consider adding other activities you enjoy. Riding a bike, dancing, yoga, swimming, jogging, etc.
  • Be honest with yourself. Sometimes, it can be difficult to face the truths about our unhealthy habits, but you cannot move forward if you cannot face the truth. Emotional ties to obesity can be the toughest to confront. The sooner you are honest with your connections to your weight issues, the sooner you can begin to work to heal them.
  • Ask for help! Talk to your health care practitioner about helping you to make a plan. This plan may include seeking the guidance of a nutritionist and personal trainer. Do not worry what people will think of you. Have confidence to seek help from others; you should not have to do this alone! Asking for help is one of the best gifts you can give yourself.
  • Enlist a friend’s help. Partner up with your husband, boyfriend, or close friend, who is in the same boat. You are more likely to stick to your plan if you know someone else is relying on you to help them. This will also help you to reduce isolation or depression.
  • Reduce stress. I know all of this seems easier said than done. Because of that, you may feel overwhelmed. Increase in stress can also contribute to hormonal imbalance and infertility. Do one stress relieving activity a day. Meditate, exercise, yoga, journal, counseling, prayer, acupuncture, calming herbs – all of these are ideas to help you keep stress at bay.
  • Believe in yourself! I know you can change, I believe in you.

Herbs and Supplements
Because of chronic elevated insulin levels due to obesity, it is first and foremost important to lower body fat. No amount of herbs or supplements is going to be effective if body fat remains high and lifestyle and diet changes are not put into place permanently. There are many supportive herbs and supplements out there, but an obese person’s body cannot respond to these as well. The first goal must be to reduce body fat, lose weight, and maintain a healthy weight, long-term. Herbs and supplements may aid in helping to boost fertility along the way, but they cannot be relied on as the solution.

Facts about Medical Options for Obesity Related Infertility
Women and men who seek infertility treatments from their doctors, are more likely to need higher dosages of fertility medications. This may have long-term health implications. Medical fertility treatments are also less likely to be as effective for obese couples. Using fertility medications alone, without weight reduction, is less likely to have positive outcomes. Fertility medications do not solve the obesity problem, even though they may aid in pregnancy.

Long-term diet and lifestyle changes are the most important factor in successful fertility treatment, whether it be natural support or medical fertility treatments.

Helpful Resources
Natural Fertility Diet:
21 Day Fertility Diet Challenge:
Fertility Yoga:
Absent Period:
Men’s Fertility:
Male Fertility Diet:

“Choice is a gift given to everyone. It is a powerful gift that can change your life.”-Unknown


Dr. Christine Traxler M.D., OB/GYN
Dr. Christine Traxler M.D., OB/GYN

Dr. Traxler is a University-trained obstetrician/gynecologist, working with patients in Minnesota for over 20 years. She is a professional medical writer; having authored multiple books on pregnancy and childbirth; textbooks and coursework for medical students and other healthcare providers; and has written over 1000 articles on medical, health, and wellness topics.  Dr. Traxler attended the University of Minnesota College of Biological Sciences and University of Minnesota Medical School,  earning a degree in biochemistry with summa cum laude honors in 1981,  and receiving her Medical Doctorate degree (MD) in 1986.

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  1. Avatar

    I have just checked my BMI and I’m not over weight. I still am going to change how I eat and what I eat. I want to lead a healthy life.

  2. Update 2014 – We are back! We have been away for a while and we sure have missed all of your wonderful questions and thoughts on our articles. Moving forward, one of our staff herbalists will be here to respond to comments! We look forward to connecting with our readers once again!

  3. Avatar

    hi im 17 years old and I’m having a hard time getting my period. It has been 6 months already, and it hasn’t come yet. I am very worried. I’m scared, and I don’t feel like a women. This started about a year and some months. Last y
    ear when my boyfriend got arressted, thats when it started my irregular period. I have been in so much stress, my boyfriend was locked up for one year and since that year I haved only gotten my period 3 times that year, I wasn’t really worried because I knew I want pregnant or anything, I though it was because I was stressing. When he got out which was about 5 months ago. And I still haven’t Gotten my period and now I’m really worried, we have sex almost eveyday, and we have unprotected sex, I’m not in any birth controls, he comes inside of me everytime we have sex, I took a pregnancy test just to check if I’m pregnant or not, but it was negative, I feel the same, I weight the same and I haven’t had any pregnancy sympthoms, so I guess I’m not pregant. I’m 5.11 and I weight about 157. I don’t think I’m overweight, I look good and I don’t think that’s the problem, I eat healthy, so I really don’t know what’s wrong with my body, my period cycle. Can someone help me?? I need to know what’s wrong with me and I can’t take it no more.. !!

  4. Avatar

    Can obesity be linked to frequent miscarriages?