For couples who are trying to conceive, new research indicates keeping cholesterol in a healthy range may increase chances. A study conducted collaboratively by the National Institutes of Health, the University at Buffalo, and Emory University, reveals a link that indicates high cholesterol may impair fertility in couples.

The study, which was published in The Journal of Clinical Endocrinology and Metabolism, measured the man and the woman’s cholesterol level and found on average that when both or just the woman had high cholesterol, it took longer for them to become pregnant. The woman’s cholesterol level seems to be the common denominator in risk factor of conception.

Researchers studied the data that was collected from 501 couples from various counties throughout Michigan and Texas between 2005 and 2009. The couples, who were not being treated for infertility but were simply trying to conceive, were already part of another study called the “Longitudinal Investigation of Fertility and the Environment (LIFE), which was used to find a link between infertility and exposure to lifestyle and environmental chemicals.

"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," said, Enrique Schisterman, Ph.D., the study’s co-author and chief of the Epidemiology Branch at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).

The women were between the ages of 18 to 44, while the men were of at least 18-years-old, and were followed until they conceived or up to one year of trying to conceive. They provided blood samples for the researchers to test for free cholesterol, which means they made no distinction between HDL cholesterol, LDL cholesterol, and triglycerides.

HDL cholesterol, or high-density lipoprotein cholesterol, is known as the good cholesterol because it helps prevent arteries from becoming blocked. Conversely, LDL or low-density lipoprotein cholesterol is the bad cholesterol and high levels indicate a buildup on the inside of artery walls, which will put you at major risk for heart disease and blockages that lead to heart attacks, according to the American Heart Association. Triglycerides are a different kind of fat that are used to store excess energy from your diet, and high levels are often caused from being overweight or obese, however there are disease or genetic disorders that can cause high levels.

The Mayo Clinical recommends LDL levels stay below 130 milligrams per deciliter of blood, while triglyceride levels should remain under 100 mg/DL, and HDL levels above should be above 60 mg/DL.

"We've long known that high cholesterol levels increase the risk for heart disease," Schisterman said. "In addition to safeguarding their health, our results suggest that couples wishing to achieve pregnancy could improve their chances by first ensuring that their cholesterol levels are in an acceptable range."

The probability a couple had of successfully become pregnant was calculated by a statistical measurement, called the fecundability odds rations, which measured estimates of each cycle based on their blood to cholesterol ratio. Potential differences in races, age, body mass index, and education were also taken into account and among study participants; Hispanic males had the highest cholesterol levels.  

The researchers aren’t in the dark about why there could be a possible connection between cholesterol and fertility. They believe that because the body uses cholesterol to make hormones, including sex hormones like testosterone and estrogen, a high level of cholesterol could be throwing the body’s balance completely off.