High cholesterol linked to poor fertility

Cholesterol
levels may affect how long it takes to conceive, a study that followed
couples for one year suggests.

The research, conducted
by the US National Institutes of Health, suggests that high cholesterol is
linked to lower levels of fertility in both men and women.

'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 lead
author Dr Enrique
Schisterman.

The
study followed 501 couples in the USA who were trying to conceive and were not
undergoing any fertility treatments. Scientists took blood samples and measured
the total amount of cholesterol in their blood to determine their 'free
cholesterol' level.

They found
that of the couples who did not conceive during the 12-month study period, both
the man and woman had, on average, higher cholesterol levels. Couples in which
the woman had a high cholesterol level, but the man did not, also took longer
to achieve pregnancy compared to couples with normal free cholesterol levels.

The
free cholesterol test used in this research differs from the standard
cholesterol test given by doctors, which measures levels of 'good cholesterol' (HDL, high-density lipoprotein)
and 'bad' (LDL, low-density lipoprotein). However, Dr Schisterman said that high free cholesterol levels
are likely to indicate an 'unfavorable' HDL to LDL ratio.

The
researchers believe that their findings may be explained by the role that cholesterol
plays in the production of hormones such as testosterone and oestrogen. This is
not the first time that a link between cholesterol and fertility has been
found, with an unrelated study from 2012 showing that high cholesterol levels are
linked with low sperm quality. However, this research found that high cholesterol
in men only led to a longer time to pregnancy when their partner also had high
cholesterol.

Dr Enrique
Schisterman said: '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'.

But Professor
Neil McClure, a fertility specialist at Queen’s University Belfast, told
the Daily Mail that couples should not solely focus on cholesterol levels,
saying: 'The take-home message is that we need to be as fit and well and
healthy as we possibly can if we are thinking about trying to conceive'.