Cholesterol levels both high and low linked to premature births

Oct 3 2007

A new study suggests that not only is a very low level of cholesterol a danger to pregnant women, but high cholesterol too increases the risk of premature birth.

Cholesterol clearly plays a key role in the development of the fetus and researchers say too little may be as bad as too much during pregnancy.

In a study by scientists at the National Human Genome Research Institute previous findings linking high cholesterol to a raised risk of premature birth were confirmed but the researchers surprisingly found low cholesterol levels also seemed to raise the risk.

Lead researcher Dr. Max Muenke says it appears that too little cholesterol may be as bad as too much cholesterol during pregnancy, but more research was needed to confirm the findings.

Prematurity is linked to an increased risk of a plethora of health problems, including lung and heart conditions, blindness, deafness and also learning difficulties.

For the study the researchers observed cholesterol levels of more than 1,000 women from South Carolina from their second trimester of pregnancy along with their newborn babies.

The women were between the ages of 21 and 34, all were non diabetic, nonsmokers and carrying only one child.

They found that 5% of women with moderate cholesterol levels gave birth prematurely; this contrasted to about a 12% prematurity rate among women with the highest cholesterol levels, while amongst white women with the lowest cholesterol levels it was 21%.

Among African American women in the low-cholesterol category however no increase was observed.

No difference in the rate of birth defects was found but women with very low cholesterol were more likely to give birth to babies with a smaller head size.

Dr. Muenke says the right amount of cholesterol is fundamental for good health, both before and after birth; but during pregnancy, cholesterol is critical for both the placenta and the developing baby, including the brain.

As a rule low maternal cholesterol levels can be related to a woman's genetic make-up, but factors such as diet may also have an effect.

Experts say that underweight women have a tendency to give birth early and it is known that the uterus will contract less efficiently in women who have a lot of blood lipids.

They say it is therefore possible that the converse could be true and the uterus is more excitable and more likely to deliver spontaneously if blood lipid levels are low.

Premature birth could also possibly be the result of genetics and environmental factors such as stress, poor nutrition, and infection.

The study is published in the journal Pediatrics.