Tips for High Cholesterol During Pregnancy: Are There Risks? Should You Lower It?

Many women find themselves with high cholesterol during pregnancy. However, doctors seem to believe that there are no risks. In fact, many do not even prescribe tests to monitor it. Let’s find out why it increases and what should be done to (if necessary) lower it.

Pregnancy is a period of waiting and there are many things that need to be done to prepare for the happy event. Among these, there are many types of tests – sometimes even too many, especially considering that those exempt from the ticket payment are definitely fewer.

Among those apparently less useful is cholesterol measurement. Yet, when gynecologists prescribe it, cholesterol levels during pregnancy always turn out to be high. So why shouldn’t it be measured? Does having high cholesterol during pregnancy not entail risks?

Why is cholesterol high during pregnancy?

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

In women of childbearing age, having high cholesterol before pregnancy entails a higher risk of premature birth. On the other hand, preterm birth is also associated with particularly low cholesterol levels before pregnancy. Indeed, this molecule plays a very important role even before gestation. In the stages preceding the implantation of the embryo in the uterine wall, the ovary (or rather, the corpus luteum formed inside it after ovulation) uses cholesterol to produce the typical pregnancy hormone: progesterone. After implantation, it continues to be important to support fetal development until the fetus's own liver begins to produce it independently.

During pregnancy, the increase in cholesterol is one of the metabolic changes considered normal consequences of gestation. In fact, fetal development involves a series of physiological changes in the expectant mother, who undergoes a real adaptation process involving behavioral spheres, respiratory processes, cardiovascular function, and metabolism. The blood pumped by the heart increases, blood sugar levels rise, and cholesterol concentrations also increase, by a variable amount between 50 and 70%.

This increase responds to the need to use this molecule to produce the hormones that allow the pregnancy to continue, such as the aforementioned progesterone and estrogens. In particular, high concentrations of estrogens lead to an increase in total cholesterol and that commonly known as “bad cholesterol” (LDL) and the increase in blood cholesterol concentration is directly proportional to that of progesterone. Additionally, blood fats increase as gestation progresses to meet the fetus's needs.

Currently, no defined reference intervals exist for cholesterol levels during pregnancy. It is known, however, that their increase in maternal blood begins in 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 levels (the so-called “good cholesterol”) between 16 mg/dL and 66 mg/dL;
• LDL levels between 23 and 110 mg/dL.

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

Regarding the “bad” form, in 60% of cases LDL cholesterol levels during pregnancy exceed 55 mg/dL. The most interesting phenomenon is the increase of small dense LDL particles, which are the most dangerous for cardiovascular health; however, it seems that, at least in the intermediate stages of gestation, this increase is balanced by an increase in protective molecules, including “good cholesterol.”

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

High cholesterol during pregnancy: risks 

To date, having high cholesterol during pregnancy is not considered a pathological condition, and it is usually not believed to pose risks to the mother’s health or fetal survival. However, this does not mean that the metabolic changes occurring in a pregnant woman have no consequences.

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

The fetus obtains 20% of the cholesterol it needs in the early stages of gestation from maternal blood. In the third trimester, however, maternal cholesterol no longer crosses the placenta. In general, the exact amount of cholesterol passing from mother to child is still to be defined, but it seems clear that maternal blood cholesterol levels influence those present in the child.

Moreover, the case of high cholesterol in pregnancy supports the intriguing theory that the future health of the child also depends on what happens to them in the womb. In fact, having high cholesterol in pregnancy impacts the newborn’s health, for example because it is associated with the risk of atherosclerotic plaque formation, i.e., those alterations of the artery wall that can lead to serious and dangerous events such as heart attack and stroke.

What exactly happens is not yet clear. Studies conducted on the topic suggest that high cholesterol favors modifications of the placenta through regulation of the expression of certain genes. These changes would alter placental function; it is thought, for example, that the increase of cholesterol in the future mother’s blood could increase the amount of cholesterol that can pass into the fetal blood.

High cholesterol during pregnancy: what to eat

In short, many doubts remain about the possible risks of high cholesterol in pregnancy. At the moment, it is still considered a physiological condition not to be treated and, in any case, the drugs normally used to lower cholesterol (statins) are contraindicated during pregnancy. Their intake could cause malformations and defects of the central nervous system in the child; for this reason, it should be stopped 1-2 months before conception or as soon as pregnancy is discovered. Neither are other cholesterol-lowering drugs prescribed during pregnancy. To lower cholesterol in pregnancy, therefore, there is no choice but to act on lifestyle, just as should be done in case of hypercholesterolemia before conception and after childbirth.

There is no specific diet to reduce cholesterol in pregnancy. In this particular phase of life, it remains essential that the mother and the growing baby have all the nutrients they need available; it is therefore important that maternal nutrition is as varied as possible and provides an adequate amount of energy.

To counteract excessive cholesterol increase, however, attention must be paid to how many saturated fats are brought to the table. Their main sources are animal foods such as red meat, milk, and its derivatives. It is therefore better to prefer oil (better if olive oil) over butter and to replace at least part of the red meat with other sources of protein low in saturated fats, such as legumes and fish.

Speaking of the latter, it is important to remember that some fish are particularly at risk of mercury contamination, which is neurotoxic. For this reason, during pregnancy it is recommended not to eat more than 150 grams per week. This warning also limits the possibility of getting all the Omega 3 needed to best carry the pregnancy; for this reason, DHA supplements are routinely prescribed to 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 suitable for pregnant women’s needs.

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