Can carrying excess weight reduce
fertility in men and women?with inputs from experts, examines recent studies, which have established the link.
UNTIL now, carrying excess weight (being overweight) has been suspected to affect fertility but recent studies indicate that obesity may diminish a man's fertility, raises miscarriage risk, reduces In Vitro Fertilisation (IVF)/Test Tube Baby success. A new study has also linked a human gene with food and fertility.
A person is said to be obese when the ratio of the weight in kilogrammes over the height in square metres, that is the Body Mass Index (BMI), is more than 30; overweight when the BMI is between 25 and 30; and severely obese when it is over 35.
"I remember a 36-year old lady who came to our infertility clinic weighing 100kg, she was put on a diet. After three months she weighed 80kg and got pregnant the following month and delivered a baby boy.
"There was the case of another lady who went through IVF/Assisted Reproductive Technique (ART) in one of our collaborating center in Chicago for six attempts without getting pregnant. She adopted a baby and then started to loss weight while looking after the baby. She lost about 25kg from a weight of about 110kg and then became pregnant without any treatment," said Professor Oladapo Ashiru, chief medical director Medical Art Centre Maryland Ikeja Lagos, Joint Pioneer Test Tube Baby Technology in Nigeria, and an Adjunct Professor at the University of Illinois at Chicago, United States.
"I had a patient, a male of about 33 years old with low sperm count. He weighed 117 kilograms and had a lot of weight around his abdomen. He had been married for three years and half, and could not impregnate the wife. I told him that if he could lose just 10 kilogrammes the wife would take in. I told him to start eating only one major meal in a day, more fruits and vegetables, not to eat after 7 p.m. and start exercising (preferably brisk walking) at least 30 minutes a day; that was in January 2001. By April the wife took in and now the couple have four children," said Dr. Ugochukwu Chukwunenye, a consultant gynaecologist and obstetrician at Optimal Specialist Hospital Surulere, Lagos.
Ashiru said: "The presentation that obesity lowers fertility in men and women is very correct. I published similar observations on a continuous basis in the Reproductive Health Magazine based on my observation of managing infertility cases over the last two decades. The following facts have been well observed and documented by us. Patients who are over weighed find it difficult to get pregnant; Patients who are over weighed and loss weight are able to get pregnant easily.
"With regards to men, obesity is associated with low sperm count, decrease libido and erectile dysfunction. The pathway is both hormonal and vascular. The hormonal one is similar to what occurs in women, which is the adrenal stress or adrenal fatigue compromising the reproductive hormones that in this case cause sperm production. The second pathway is vascular, in this case the fat from obesity will block the arteries that supply and nourish the male organ and therefore render it ineffective and unable to sustain erection."
Chukwunenye said: "Obesity, a form of malnutrition, is known to adversely affect the function of virtually all organs in the human body. In the reproductive system, it has been associated with infertility or sub-fertility. It has been associated with menstrual cycle disturbance, anovulation, erectile dysfunction and disturbance of sperm production."
Ashiru's and Chukwunenye's experiences were corroborated by Prof. Udoh O. Obioha, an obesity expert and clinical professor of Family Medicine at the University of North Dakota School of Medicine and Health Services, United States (US); Prof. Augustine Ohvoworiole, the president, Nigerian Society of Endocrinology and Metabolism (NSEM); and recent studies.
Indeed, a new study suggests being obese may dim a man's chances of becoming a father, even if he is otherwise healthy.
Researchers found that among 87 healthy men ages 19 to 48, those who were obese were less likely to have ever fathered a child. More importantly, they showed hormonal differences that point to a reduced reproductive capacity, the researchers report in the journal Fertility and Sterility.
Compared with their thinner counterparts, obese men had lower levels of testosterone in their blood, as well as lower levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) -- both essential to reproduction.
According to the researchers, these relatively low levels of LH and FSH are suggestive of a "partial" hypogonadotropic hypogonadism. This is a condition in which the testes do not function properly due to signaling problems in the hypothalamus or pituitary gland, two brain structures involved in hormone secretion.
The findings suggest that obesity alone is an "infertility factor" in otherwise healthy men, write Dr. Eric M. Pauli and his colleagues at the Pennsylvania State University College of Medicine in Hershey, United States.
Of the 87 men in the study, 68 per cent had had a child. Pauli's team found that the average body mass index, or BMI, was lower among these men compared with those who'd never fathered a child; in the former group, the average BMI was 28, which falls into the range for "overweight," while the average BMI for childless men was nearly 32, which falls into the "obese" range.
When the researchers assessed the men for several reproductive hormones, they found that the more obese a man was, the lower was his LH and FSH levels. On the other hand, increasing obesity correlated with increasing estrogen levels.
Excess body fat, Pauli's team explains, may increase the conversion of testosterone to estrogen in a man's blood. Such hormone alterations could, in turn, signal the brain to suppress FSH and LH production.
Past studies have linked obesity with a dampened libido and increased risk of erectile dysfunction, the researchers note. Those effects, they say, along with the hormonal alterations seen in this study, could act together to decrease an obese man's fertility.
A major study has found an overweight woman's chance of getting pregnant steadily falls as her weight increases. Among 3,000 women with fertility problems, there was a four per cent drop in the chance of pregnancy for every BMI rise above a certain point.
Dutch scientists, writing for the journal Human Reproduction, said that very obese women fared the worst. The level of obesity among would-be mothers is increasing around the world.
Doctors know that this affects a woman's chances of getting pregnant naturally, but are more worried by the increased risks to her health - and the health of her baby - that the extra weight poses.
The study by researchers at the Academic Medical Center in Amsterdam is the first to follow a large group of women trying for a baby, and to see directly what effects their body mass had on the outcome.
All the women in the study had come to see fertility doctors, but there was no obvious reason for their failure to conceive, as they were still ovulating normally.
Some women with "unexplained infertility" do go on to become pregnant naturally. The study found that there was a clear relationship between their BMI and their likelihood of achieving this.
Compared with women with a BMI between 21 and 29, for every BMI point between 30 and 35 there was a four per cent drop in conception rates. Severely obese women, with a BMI of over 35, were between 26 per cent and 49 per cent less likely to conceive compared with a BMI between 21 and 29.
Also, a recent research suggests that women who have had a miscarriage could be at greater risk of miscarrying again if they are obese. A team from London's St Mary's Hospital followed the progress of 696 women whose miscarriages were classed as "unexplained" by a specialist clinic.
The team told a conference in Canada the risk of a further miscarriage was raised by 73 per cent if the woman was obese. However, an obesity specialist said it was potentially dangerous to try to lose weight when already pregnant.
Although the links between being obese and having problems conceiving and complications during pregnancy are well known, this study claims to be the first to look specifically at "recurrent" miscarriage, for which there is often no obvious cause.
Of the 696 women whose cases were followed, more than half were of "normal" weight, 30 per cent were overweight, and 15 per cent were obese, meaning they had a BMI of 30 or above.
The older the woman, the higher chance she had of having another miscarriage, but, when the figures were adjusted to account for this, obesity emerged as another possible factor.
While there was no difference in the miscarriage rates for overweight, normal and underweight women, the risk of further miscarriage increased sharply for obese women.
Winnie Lo, a clinical nurse specialist at St Mary's, who presented the research at the Royal College of Obstetrics and Gynaecology's international meeting in Montreal, said: "This is the first study to look directly at the link between BMI and recurrent miscarriage. It shows that obese women who experience recurrent miscarriage are at greater risk of subsequent pregnancy loss. All women with recurrent miscarriage should be weighed at their first consultation. Those who are found to be obese should be counselled regarding the benefits of weight loss."
Dr Nick Finer, an endocrinologist with an interest in obesity from Addenbrooke's Hospital near Cambridge, said that the findings were "unsurprising". "We already know that the chances of fertility are less with increasing BMI, the risks of foetal malformation increase, alongside the risks of other adverse pregnancy outcomes."
He said that, while the reason why obesity might cause such problems was not clear, it was possible that it increased inflammation, harming the chances of a successful pregnancy.
However, he warned that crash diets during pregnancy would never be recommended as a means of increasing the chances of success. "There are good reasons to try to lose weight before getting pregnant, but it is recommended that women do not try to do this once pregnancy is established, as it could cause problems." _
Before now, medical experts had raised alarm over the rising incidence of obesity in the country. According to them, the disease is linked to four other diseases, which ultimately reduce life span and life expectancy of Nigerians.
Life span is the maximum number of years lived. Life expectancy is the number of years lived in good health (quality life). Latest statistics indicated that Nigeria has life expectancy of 47.44 years.
The four diseases are cancer, stroke, heart attack and complications of diabetes. Obesity is said to be more common among the affluent due to their sedentary life styles and Western diets. Two of the major preventive measures, according to the medical experts, are eating of traditional foods and regular exercises.
Meanwhile, IVF experts say obese women should be refused fertility treatment until they lose weight. Professionals in the United Kingdom are being urged to deny treatment to women with a BMI of more than 35.
Where possible, the British Fertility Society says IVF should be offered only when her BMI has dropped below 30 - a figure based on both height and weight.
One obesity expert branded the new guidelines "discriminatory". But the British Fertility Society (BFS) said its new advice was based on what was best for both the mother and her baby.
"Obesity reduces the chances that a woman will conceive naturally and decreases the possibility that fertility treatment will be successful," said Mr Tony Rutherford, the chair of the BFS's policy committee. "It also increases the risk of complications during fertility treatment and pregnancy and endangers the health and welfare of both mother and child."
Among the "complications" listed was the difficulty of providing safe anaesthesia for obese women during procedures, as well as problems with viewing ovaries on an ultrasound scan.
Obesity is also thought to raise a woman's risk of miscarriage after IVF treatment. The BFS guidelines have no legal weight, but they are referred to by many professionals working in the field.
The chief executive of the Infertility Network endorsed the recommendations, but stressed women must be offered the help they needed to lose weight. "We would also recommend that clinicians adopt a flexible approach where possible and look at cases on an individual basis," said Clare Brown.
But the chairman of the National Obesity Forum, Dr Colin Waine, said he found the new guidelines "troubling". "Weight loss may improve the success of treatment, and women should be made aware of that, but to deny treatment outright is discriminatory," he said. "We are getting ourselves onto an increasingly slippery slope of rationing on the basis of weight, even when overweight people may benefit immensely from treatment."
Dr Jan Willem van der Steeg, who led the study, said: "Given the increased prevalence of obesity, this is a worrying finding. We think that women should be informed about their lower pregnancy chances due to their overweight. We hypothesise that losing weight will increase the chance to conceive without treatment."
Ashiru said the issue could be explained from the endocrine view point. "As reproductive endocrinologist we know that there are established complex pathways between the ovary the adrenal gland and the pancreatic islet cell of langherhan. The Islet cells produce insulin, which helps in the break down of fats and carbohydrates. When there is two much fat in the body it will affect the metabolic process and put the adrenal gland into stress. The adrenal stress that is caused by food over load and excess fat will deprive the ovary of proper function. The overall result in simple terms
is that the hormones that should be helping to regulate ovarian function and ovulation will all be busy attending to the excess fat. I therefore want to lend support to the observation on excess weight and infertility," he said.
United States researchers have found a genetic link controlling both appetite and fertility. A gene, TORC1, appears to act as a "master switch", switching off food intake and allowing pregnancy. The gene probably offered an evolutionary advantage, by stopping women getting pregnant in times when food was scarce, the researchers said.
Mice lacking the gene were unable to reproduce, and grossly overweight, reported the journal Nature Medicine. Both underweight and severely overweight women may have fertility problems, and the research at Salk Institute in California is suggesting that TORC1 may play a role in both.
Ohvoworiole said there is already an epidemic of non-communicable diseases in Nigeria due to Western diets or refined foods and inactivity.
He said the rise in obesity in the country might lead to a decrease in life expectancy. "It is well known that obesity increases the risk of heart disease and perhaps cancer. Given that rates of obesity in Nigeria have now been increasing for several years, it is likely that there might be some impact on life expectancy," he said.
On how to resolve the situation, Ashiru advised: "Both men and women should ensure they are not over weighed. Regular exercise and good diet that is not over loaded with carbohydrate and fat are essential key factors to realising this objective."
