Tips for high cholesterol in pregnancy: are there risks? Should it be lowered?

It happens to many women to end up with high cholesterol during pregnancy. Doctors, however, seem to believe there is no risk. In fact, many do not even prescribe tests to monitor it. Let's find out why it rises and what should be done to (if anything) lower it.

Pregnancy is a period of waiting, and while waiting there are so many things you need to do to prepare for the happy event. Among these, there is no shortage of examinations of many kinds-sometimes too many, at least according to the fact that those for which you are exempt from co-payment are significantly fewer.

Among those apparently of little use is the cholesterol assay. Yet, when gynecologists prescribe it, cholesterolemia is always elevated in pregnancy. Why, then, should it not be measured? Doesn't having high cholesterol in pregnancy pose risks?

Why is cholesterol high during pregnancy?

In addition to being a key component of all cell membranes, cholesterol indirectly regulates several metabolic pathways and is the precursor to several important molecules produced by the human body, including sex hormones. However, excessive levels are considered hazardous to health at all stages of life.

In the case of women of childbearing age, having high cholesterol before pregnancy leads to an increased risk of preterm birth. On the other hand, preterm birth is also associated with particularly low cholesterol levels before pregnancy. In fact, this molecule plays a very important role even before gestation. In the stages preceding the nesting of the embryo in the wall of the uterus, the ovary (or, rather, the corpus luteum that forms inside it after ovulation) uses precisely cholesterol to produce the typical hormone of pregnancy: progesterone. After implantation, it continues to be important in supporting the development of the fetus until the fetus' own liver begins to produce it on its own.

During pregnancy, however, increased cholesterol is one of the metabolic changes that are considered normal consequences of gestation. Indeed, the development of the fetus involves a series of physiological changes in the mother-to-be, who goes through a real process of adaptation involving both behavioral and respiratory processes, cardiovascular function, and metabolism. Blood pumped by the heart increases, blood sugar levels rise, and cholesterol concentrations also rise, increasing by between 50 and 70 percent.

This increase responds to the need to use this molecule to produce the hormones that allow gestation to proceed, such as the aforementioned progesterone and estrogen. Specifically, high estrogen concentrations lead to an increase in total cholesterol and the cholesterol commonly known as "bad cholesterol" (LDL) and the increase in blood concentration of cholesterol is directly proportional to that of progesterone. In addition, blood fats also increase as gestation progresses to meet the needs of the fetus.

There are currently no defined reference ranges for cholesterol values in pregnancy. It is known, however, that their increase in maternal blood begins as early as the first trimester and is particularly evident in the second and third. According to data reported in the scientific literature, in the first trimester 78% of women have:

• Total cholesterol levels above 90 mg/dL;
• HDL (so-called "good" cholesterol) levels between 16 mg/dL and 66 mg/dL;
• LDL levels between 23 and 110 mg/dL.

Several experts consider a total cholesterol concentration at the end of pregnancy above 280-290 mg/dL or above the 75th percentile during all three trimesters as the limit beyond which to consider excessive increase.

Regarding, on the other hand, the "bad" form, in 60 percent of cases LDL cholesterol levels in pregnancy are above 55 mg/dL. The most interesting phenomenon is the increase in small, dense LDL particles, which are the most dangerous for cardiovascular health; however, it appears that, at least in the middle stages of gestation, this increase is balanced by an increase in protective molecules, including "good" cholesterol.

Generally, after pregnancy, high cholesterol returns to levels considered normal.

High cholesterol in pregnancy: the risks 

To date, having high cholesterol in pregnancy is not considered a pathological condition, and it is not usually thought to pose risks to the health of the mother or the survival of the fetus. This does not mean, however, that the metabolic changes that occur in a pregnant woman are of no consequence.

In the first and second trimesters of pregnancy, changes in lipid metabolism and blood levels of lipids leads to stimulation by estrogen, which, together with increased insulin resistance, promotes increased food intake, fat production, and increased fat mass and body weight. In the third trimester, the increase in cholesterol induced by lipase enzyme activity may promote greater development of the placenta, which, thus, can deliver more nutrients to the fetus.

The latter obtains 20 percent of the cholesterol it needs in the early stages of gestation from the mother's own blood. In the third trimester, however, the mother's cholesterol no longer crosses the placenta. In general, the exact amount of cholesterol that passes from mother to baby is yet to be determined, but it now seems clear that the levels of cholesterol in maternal blood influence those in the baby.

Not only that, the case of high cholesterol in pregnancy is evidence to support the intriguing theory that a baby's future health also depends on what happens to it in the womb. In fact, having high cholesterol in pregnancy has an impact on the health of the unborn child, for example, because it is associated with the risk of atherosclerotic plaque formation, that is, those changes in the artery wall that can lead to serious and dangerous events such as heart attack and stroke.

What exactly happens has not yet been clarified. Studies conducted on the subject suggest that high cholesterol promotes changes in the placenta through regulation of the expression of certain genes. These changes would alter the functioning of the placenta; it is thought, for example, that increased cholesterol in the future mother's blood may increase the amount of cholesterol that can pass into the fetus' blood.

High cholesterol in pregnancy: what to eat

In short, about the possible risks of high cholesterol in pregnancy, many doubts still remain. At present, it is still considered a physiological condition that should not be treated, and in any case, drugs normally used to lower cholesterolemia(statins)are contraindicated during gestation. Taking them could cause malformations and central nervous system defects in the baby; therefore, they should be discontinued 1-2 months before conception or as soon as you find out you are pregnant. Other cholesterol-lowering drugs are not prescribed during pregnancy either. To lower cholesterol in pregnancy, therefore, all that remains is to act on lifestyle, just as should be done in the case of hypercholesterolemia even before conception and after delivery.

There is no specific diet for reducing cholesterol in pregnancy. At this particular stage of life, it remains essential that the mother and the baby growing in her belly have all the nutrients they need available to them; therefore, it is important that the maternal diet be as varied as possible and provide an adequate dose of energy.

However, to counteract excessive cholesterol elevation, it is necessary to pay attention to how much saturated fat one brings to the table. Their main sources are foods of animal origin such as red meat, milk and its derivatives. It is therefore better to prefer oil (even better if olive oil) to butter, and to replace at least some of the red meat with other sources of protein low in saturated fat, such as legumes and fish.

Regarding the latter, it is important to remember that some fish are particularly at risk of contamination with mercury, which is neurotoxic. For this reason, it is recommended during pregnancy not to eat more than 150 grams per week. This warning also limits the ability to take in all the Omega 3s needed to carry on gestation as best as possible; this is why DHA supplements are routinely prescribed for pregnant women.

Finally, limiting red meat consumption could lead to cases of anemia or complicate the management of already diagnosed anemias. Fortunately, even in this case it is possible to cope by taking iron supplements tailored to the needs of pregnant women.

Bibliographic references:

Bartels Ä et al. Maternal serum cholesterol levels are elevated from the 1st trimester of pregnancy: a cross-sectional study. J Obstet Gynaecol. 2012 Nov;32(8):747-52. doi: 10.3109/01443615.2012.714017

Catov JM et al. Prepregnancy lipids related to preterm birth risk: the coronary artery risk development in young adults study. J Clin Endocrinol Metab. 2010 Aug;95(8):3711-8. doi: 10.1210/jc.2009-2028

Heart UK. Pregnancy and blood fats. Last viewed 11/01/24

Jayalekshmi VS and Ramachandran S. Maternal cholesterol levels during gestation: boon or bane for the offspring? Mol Cell Biochem. 2021 Jan;476(1):401-416. doi: 10.1007/s11010-020-03916-2