Obesity and Infertility: The relationship between them.






Obesity and infertility have been linked together by several studies. But what is the precise relationship between these two impactful diseases? And why do women who are obese have a greater risk of infertility and other pregnancy-related problems?
There is no doubt that obesity and infertility are linked and that obesity has a negative impact on fertility and couples capacity to conceive. So if you are obese how do you know? It’s all to do with your height/weight ratio known as your BMI (Body Mass Index).

BMI is a measure of body fat calculated from an individual’s weight and height (kg/m2). The internationally accepted range for BMI is from less than 18.5 kg/m2 (underweight) to 30 kg/m2 or over (obese). Women with BMI over 30 kg/m2 take longer to conceive, compared with women with lower BMI, even after adjusting for other factors such as menstrual irregularity. For anyone in the US that means anyone with a BMI over 30 is obese

For infertile anovulatory women with a BMI of over 29 kg/m2, there is evidence that a supervised weight loss program or a group program including exercise, dietary advice and support helps to reduce weight, resume ovulation and improve pregnancy rates.



But how does obesity cause infertility?

Obesity results in an increased production of estrogen; this hormonal imbalance in turn interferes with ovulation, which of course, is the basis of successful conception.

Ovulatory disorders are the leading cause of female infertility, resulting in the disruption of hormones, menstrual cycles, and conception. Approximately 15% of such disorders are linked to weight disorders, mainly being overweight and obese.

Having high estrogen levels associated with obesity can also result in pre-cancerous transformations (usually reversible) in the uterus.

Estrogen is found in two places in the female body, in the ovaries where the majority is produced and in the adrenal glands, which produce a small amount. Estrogens are synthesized from cholesterol in the ovaries in response to pituitary hormones. So if there is too much cholesterol in your diet you will have an over supply or imbalance of estrogen it may affect your ovary function and disrupt your natural monthly ovulation cycle.

Ovulatory disorders are the leading cause of female infertility, resulting in the disruption of hormones, menstrual cycles, and conception. Approximately 15% of such disorders are linked to weight disorders, mainly being overweight and obese.



Obesity and Infertility relationship with PCOS

The main factors implicated in obesity and infertility is the association of insulin excess and insulin resistance. These adverse effects of obesity are specifically evident in polycystic ovary syndrome (PCOS).

Obesity has a huge effect on polycystic ovary syndrome and that excessive weight may increase reproductive abnormalities in women with PCOS, and that obesity is prevalent in women with PCOS.

However the levels of obesity seen in women with PCOS may just reflect the current prevalence of obesity in the general population as a result of poor diet and lack of exercise.

In women, early onset of obesity may find that they have menstration irregularities, chronic oligo-anovulation or PCOS leading to infertility in the adult age. Being an obese female can also increase risk of miscarriages and also reduce the chances of ART (Assisted Reproductive Technology) and pregnancy, when the body mass index exceeds 30 kg/m.

However, the levels of obesity seen in women with PCOS may just reflect the current prevalence of obesity in the general population as a result of poor diet and lack of exercise.

When we go back to causes of infertility in the region of 15% of all causes are linked to weight disorder, this being either over weight or obese.

According to several studies, women whose obesity could be traced back to their childhood (childhood obesity) had a greater risk of amenorrhœa, a condition in which menstrual cycles are absent.

The likely association of Obesity and Infertility outcomes.

Fertility can be negatively affected by obesity. In women, early onset of obesity favours the development of menstrual irregularities, chronic oligo-anovulation and infertility in the adult age.

Obesity in women can also increase risk of miscarriages and impair the outcomes of assisted reproductive technologies and pregnancy, when the body mass index exceeds 30 kg/m. The main factors implicated in the association may be insulin excess and insulin resistance. These adverse effects of obesity are specifically evident in polycystic ovary syndrome (PCOS).

Women with BMI over 30 kg/m2 take longer to conceive, compared with women with lower BMI, even after adjusting for other factors such as menstrual irregularity.

Women who are overweight are less likely to respond to fertility drugs as being over weight will interfere with the absorption of medication used in treating fertility. Many clinics often refuse further treatment until a persons weight is at a treatable level.

High estrogen levels associated with obesity can also result in pre-cancerous transformations (usually reversible) in the uterus.

A BMI of 30 or over was reported to be an independent risk factor for spontaneous abortion in women who were oocyte/egg recipients.

According to several studies, women whose obesity could be traced back to their childhood (childhood obesity) had a greater risk of amenorrhea, a condition in which menstrual cycles are absent.

An increased risk of miscarriage has been reported in moderately obese women (BMI 25–27.9 kg/m2) with polycystic ovary syndrome PCOS; undergoing ovulation induction.

Obesity and infertility are linked in many different ways although the solutions maybe hard for some it is reversible.

Recommendations for Obesity and infertility issues

Although further research and observation is needed in this area before any conclusions can truly be made. Any advice given at this stage would be that, regardless of fertility or medical problems, healthy eating and exercise are the most sensible lifestyle choices.

For infertile anovulatory women with BMI of over 29 kg/m2, there is evidence that a supervised weight loss program or a group program including exercise, dietary advice and support helps to reduce weight, resume ovulation and improve pregnancy rates.

Initial advice to people concerned about delays in conception Women who have a body mass index of more than 29 should be informed that they are likely to take longer to conceive.

Women who have a body mass index of more than 29 and who are not ovulating should be informed that losing weight is likely to increase their chance of conception.

Women should be informed that participating in a group program involving exercise and dietary advice leads to more pregnancies than weight loss advice alone.

It has been reported that a weight loss program may improve ovulation and pregnancy outcomes in obese infertile women for all forms of fertility treatment, including ovulation induction, IUI and IVF treatment.

Women who are have a BMI between 25.8 to 30.8 kg/m2) have a higher chance for spontaneous abortion after IVF or ICSI. But for a natural birth overcoming

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Obese women with an BMI over 25 are associated with lower pregnancy rates after IVF when compared with women with a BMI of 25 kg/m2 or under.

Extremes of BMI (over 25–28 kg/m2 or under 20 kg/m2) have been associated with negative effects on IVF parameters leading to decreased chances of pregnancy.

Women should be informed that female body mass index should ideally be in the range 19–24 before commencing assisted reproduction, and that a female body mass index outside this range is likely to reduce the success of assisted reproduction procedures.

Overall summary of obesity and infertility

Much more attention should be paid to the impact of obesity and infertility in both women and men. This appears to be particularly important for women before assisted reproductive technologies are used. Treatment of obesity may improve androgen imbalance and erectile dysfunction, the major causes of infertility in obese men.

But overall, if obesity is impacting on your capacity to conceive, then your only option is to motivate yourself and get into the fertile BMI zone, we appreciate that it is not easy, but find a program which suits you and gives you lots of positive advice and more importantly encouragement.

GOOD LUCK!