How does high levels of Cholesterol affect fertility and pregnancy

Cholesterol plays a key role in the overall functioning of the body. Its effects on cardiovascular health is the most studied. However, adequate cholesterol levels are important for many other functions, including fertility.  

Cholesterol is used by the body to produce sex hormones such as testosterone, oestradiol and progesterone, which play a key role in reproductive process in both men and women.

Increased cholesterol levels lead to changes in these processes and can interfere with reproductive functions, both female fertility and male fertility and the ability to become pregnant, making it more difficult to achieve pregnancy.

It should also be borne in mind that high cholesterol often goes hand in hand with other factors such as excess body weight, a sedentary lifestyle or smoking; factors that make conception difficult both naturally and through the use of assisted reproduction techniques.

What levels of cholesterol are considered normal?

In general, cholesterol levels in the adult population would be classified as follows:

• Total Cholesterol

Healthy < 200 mg/dL          Limit   201-240 mg/dL         High > 240 mg/dL

• Cholesterol LDL (bad)

Healthy < 100 mg/dL          Limit   101-130 mg/dL         High > 130 mg/dL

• Cholesterol HDL (good)

It is different for men and women and it is “a protector”. This means that, the more we have, the better. A healthy cholesterol would be:

Men > 40 mg/dL     

Women > 50 mg/dL

A total cholesterol of more than 300 mg/dL will lead us to suspect hypercholesterolaemia of genetic cause.

Cholesterol and fertility, what is the link?

Couples with high cholesterol take longer to achieve pregnancy than those with normal cholesterol levels, as shown by the LIFE study (2014)^{Ref. 1}

The same applies if one of the members of the couple has high cholesterol levels.

• Female fertility. In women, we have the Pugh et al. (2017)^{Ref. 2} study which shows that high cholesterol levels can make it difficult to become pregnant.

• Male fertility. In men, the Schisterman (2014)^{Ref. 3}  study and the Saez (2019)^{Ref. 4} study, show that high cholesterol levels affect semen quality. In addition, experimental studies published in 2023 in rats (Liu)^{Ref. 5} and rabbits (Funes)^{Ref. 6} confirm the impact of a high-fat diet on testicular function and the improvement when olive oil is added.

Controlling cholesterol levels is highly beneficial for our general health. And now we are also aware of its benefits for female fertility and male fertility.

Therefore, if we have high cholesterol, before seeking pregnancy and especially before starting assisted reproduction treatment, it is recommended to evaluate our lifestyle habits to try to make them as healthy as possible.

Risks to avoid and recommendations

• Cut down on smoking and avoid alcohol.
• No to sedentary lifestyle: be active. A minimum of daily exercise is recommended, walking to places, taking the stairs instead of the lift…
• Healthy diet. The most suitable diet for people with high cholesterol is the Mediterranean diet, based on fresh, unprocessed products.

High cholesterol in pregnancy

What is the reason for this?

Cholesterol and triglyceride levels increase during pregnancy, especially in the third trimester, and return to pre-pregnancy levels after delivery. This increase has been linked to placental hormone production, especially progesterone.

High level risks

Elevated cholesterol levels have been linked to the pre-eclampsia^Ref.7 development, gestational diabetes and prematurity. There is no clear evidence of negative impact on the baby.

What to do to lower cholesterol in pregnancy?

Drugs used for cholesterol control cannot be used during pregnancy and should not be started. Women who take them before pregnancy should stop taking them.

Management is strictly conservative with a healthy diet based, as mentioned above, on the Mediterranean diet and exercise if the condition of the pregnancy does not contraindicate it (threat of miscarriage or premature birth, high blood pressure, etc.).

The recommended diet in pregnancy is composed on the following:

• Fresh vegetables (fruits and vegetable with antioxidant power, which counteracts the oxidative stress of high cholesterol).

• Legumes and cereals (preferably whole grains).

• Lean meats and fish (which provide fats such as mono and polyunsaturated fatty acids, omega-3).

• It is important to consume olive oil as part of the Mediterranean diet.

• Processed foods high in sugar, salt and saturated fats should be avoided.

References

• Schisterman EF, Mumford SL, Browne RW, Barr DB, Chen Z, Louis GM. Lipid concentrations and couple fecundity: the LIFE study. J Clin Endocrinol Metab. 2014 Aug;99(8):2786-94. doi: 10.1210/jc.2013-3936. Epub 2014 May 20. PMID: 24846535; PMCID: PMC4121020.

• Pugh SJ, Schisterman EF, Browne RW, Lynch AM, Mumford SL, Perkins NJ, Silver R, Sjaarda L, Stanford JB, Wactawski-Wende J, Wilcox B, Grantz KL. Preconception maternal lipoprotein levels in relation to fecundability. Hum Reprod. 2017 May 1;32(5):1055-1063. doi: 10.1093/humrep/dex052. PMID: 28333301; PMCID: PMC6075456.

• Schisterman EF, Mumford SL, Chen Z, Browne RW, Boyd Barr D, Kim S, Buck Louis GM. Lipid concentrations and semen quality: the LIFE study. Andrology. 2014 May;2(3):408-15. doi: 10.1111/j.2047-2927.2014.00198.x. Epub 2014 Mar 5. PMID: 24596332; PMCID: PMC3999259.

• Saez F, Drevet JR. Dietary Cholesterol and Lipid Overload: Impact on Male Fertility. Oxid Med Cell Longev. 2019 Dec 6;2019:4521786. doi: 10.1155/2019/4521786. PMID: 31885793; PMCID: PMC6925770.

• Liu L, Zhang M, Jiang F, Luo D, Liu S, Su Y, Guan Q, Yu C. High cholesterol diet-induced testicular dysfunction in rats. Hormones (Athens). 2023 Dec;22(4):685-694. doi: 10.1007/s42000-023-00472-4. Epub 2023 Aug 18. PMID: 37596375.

• Funes AK, Avena MV, Ibañez J, Simón L, Ituarte L, Colombo R, Roldán A, Conte MI, Monclus MÁ, Boarelli P, Fornés MW, Saez Lancellotti TE. Extra-virgin olive oil ameliorates high-fat diet-induced seminal and testicular disorders by modulating the cholesterol pathway. Andrology. 2023 Sep;11(6):1203-1217. doi: 10.1111/andr.13398. Epub 2023 Feb 11. PMID: 36695747.

• Wild RA, Edwards RK, Zhao D, Hansen KR, Kim AS, Wrenn DS. Highly Atherogenic Lipid Particles are Associated with Preeclampsia After Successful Fertility Treatment for Obese Women who have Unexplained Infertility. Reprod Sci. 2023 Aug;30(8):2495-2502. doi: 10.1007/s43032-023-01197-w. Epub 2023 Feb 22. PMID: 36813973; PMCID: PMC10442456.

Dr Pino Navarro (n. º doctor associated 307304), endocrinologist and nutritionist at Instituto Bernabeu