
 
 (American Heart Association) 
 
 Couples with high cholesterol have more difficulty conceiving than those with normal levels of the substance in their blood, researchers reported Tuesday, in what they called the first study to link fertility difficulties to the fat molecule commonly associated with cardiovascular problems. 
 
 In a study of 501 couples who were trying to conceive, the time it took for the woman to become pregnant was longest if both partners had high cholesterol. When the woman alone had high cholesterol, pregnancy was also delayed. A man with high cholesterol did not significantly delay pregnancy if the woman's cholesterol reading was within the normal range, according to the study, conducted by the National Institutes of Health, the University at Buffalo and Emory University in Atlanta. 
 
 Cholesterol is critical to the production of hormones such as estrogen in women and testosterone in men, as well as sperm, said Enrique Schisterman, chief of the epidemiology branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, who led the study. Too much or too little cholesterol can interfere with that process, he said. 
 
 "We need optimal amounts," Schisterman said. "An excess sometimes creates an imbalance of too much hormones, or too little hormones. You have to have a sweet spot." 
 
 In addition to the link between cholesterol and fertility, Schisterman noted that the male's role in conception difficulties is noteworthy. Both partners who want to have children should focus on living healthy lifestyles and keeping cholesterol levels down, said Schisterman, who devoted his career to fertility research after he and his wife struggled to have children. They have one child born through in vitro fertilization and another who is adopted, he said. 
 
 The study, published online in the Journal of Clinical Endocrinology and Metabolism, should not be interpreted to mean that couples seeking to conceive should take common medications such as Lipitor that lower cholesterol, Schisterman said. The researchers did not look at interventions, he said. 
 
 Measures of overall cholesterol, high-density lipoproteins (HDLs), low-density lipoproteins (LDLs), and triglycerides that people are accustomed to receiving from their doctors were not used in the study. The researchers examined free cholesterol in the blood with a different metric. 
 
 Schisterman said the link between cholesterol and fertility had never been measured because it is difficult to find a population of couples trying to conceive and follow them for an extended period of time. For this study, the researchers recruited couples in Texas and Michigan from 2005 to 2009, and followed them for a year or until they became pregnant. A few dropped out during the research. 
 
 Even when they controlled for other factors that have been associated with infertility in the past, such as a high body mass index, high cholesterol clearly proved to be an additional problem, Schisterman said. ||||| NIH study links high cholesterol levels to lower fertility 
 
 Couples with highest cholesterol took longest to achieve pregnancy 
 
 High cholesterol levels may impair fertility in couples trying to achieve a pregnancy, according to a study by researchers at the National Institutes of Health, the University at Buffalo (New York), and Emory University in Atlanta. 
 
 Couples in which each partner had a high cholesterol level took the longest time to reach pregnancy. Moreover, couples in which the woman had a high cholesterol level and the man did not also took longer to achieve pregnancy when compared to couples in which both partners had cholesterol levels in the acceptable range. 
 
 “We’ve long known that high cholesterol levels increase the risk for heart disease,” said the study’s first author, Enrique Schisterman, Ph.D., chief of the Epidemiology Branch at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the institute that led the study. “In addition to safeguarding their health, our results suggest that couples wishing to achieve pregnancy would improve their chances by first ensuring that their cholesterol levels are in an acceptable range.” 
 
 The study findings were published online in JCEM, The Journal of Endocrinology and Metabolism, a publication of the Endocrine Society. 
 
 Cholesterol is a waxy, fat-like substance found in all cells of the body. It’s used to make a number of substances, including hormones and vitamin D. High blood cholesterol levels typically do not cause any signs or symptoms, but can increase the chances for heart disease. 
 
 For the current analysis, the researchers studied couples who were not being treated for infertility but who were trying to conceive a child. The researchers enrolled 501 couples from four counties in Michigan and 12 counties in Texas from 2005 to 2009. The couples were part of the Longitudinal Investigation of Fertility and the Environment (LIFE) study, established to examine the relationship between fertility and exposure to environmental chemicals and lifestyle. The women taking part in the study ranged from 18 to 44 years of age, and the men were over 18. The couples were followed until pregnancy or for up to one year of trying. 
 
 Study volunteers provided blood samples, which the researchers tested for free cholesterol. The measurement of free cholesterol is used in research, and differs from the cholesterol test given in doctors’ offices. Cholesterol tests administered by physicians measure the cholesterol subtypes: HDL cholesterol, LDL cholesterol and triglycerides. For the study, Dr. Schisterman and his colleagues relied on a test to measure the total amount of cholesterol in the blood, but which did not distinguish between cholesterol subtypes. The researchers theorized that blood cholesterol might be related to fertility as the body uses cholesterol to manufacture sex hormones like testosterone and estrogen. 
 
 The researchers calculated the probability that a couple would achieve pregnancy by using a statistical measure called the fecundability odds ratio (FOR). The measure estimates couples’ probability of pregnancy each cycle, based on their serum cholesterol concentrations. 
 
 The researchers found that on average, those couples in which the female did not become pregnant during the study duration had the highest free cholesterol levels. In general, high free cholesterol levels were correlated with longer times to pregnancy and lower fecundability odds ratios. Couples in which the female had a high cholesterol level and the male did not also took longer to achieve pregnancy when compared to couples in which both partners had cholesterol levels in the acceptable range. In their analysis, the study authors accounted for potential racial differences, as well as differences by age, body mass index, and education. 
 
 Among study participants, Hispanic males had the highest free cholesterol levels. 
 
 Standard cholesterol testing by physicians typically evaluates cholesterol scores in terms of the balance of HDL and LDL cholesterol, with a low ratio of HDL to LDL cholesterol signifying an increased risk for heart disease. Although the researchers did not evaluate the ratio of these two cholesterol subtypes, Dr. Schisterman said that high free cholesterol levels are likely to indicate an unfavorable HDL to LDL ratio. 
 
 “From our data, it would appear that high cholesterol levels not only increase the risk for cardiovascular disease, but also reduce couples’ chances of pregnancy,” Dr. Schisterman said. 
 
 About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute’s website at http://www.nichd.nih.gov. 
 
 About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov. 
 
 NIH...Turning Discovery Into Health®
– High cholesterol is bad for more than just your arteries. A study released this week found that high cholesterol may make it tougher for couples to get pregnant, the Washington Post reports. Researchers came to their conclusion after following 501 couples who were trying to conceive (and controlling for other potential infertility contributors, like body mass index). Their finding held true when either both partners or just the woman had high cholesterol; no significant effect was seen if only the man had the condition. The effect was the most pronounced when both would-be parents had high levels, per a statement released by the National Institutes of Health. As study leader Enrique Schisterman explains, cholesterol plays a key role in the production of hormones like estrogen and testosterone. "An excess sometimes creates an imbalance of too much hormones, or too little hormones. You have to have a sweet spot." Schisterman cautions that the finding doesn't mean couples should rush to take cholesterol-lowering drugs, but he does encourage couples looking to become parents to lead a healthy lifestyle. (Click to read about another breakthrough in the study of fertility involving a protein called Juno.)