What factors influence egg quality in women and how can it be optimized?

Factors Influencing Egg Quality in Women and Optimization Strategies

Age is the most significant determinant of egg quality in women, with a sharp decline occurring after age 35, but several modifiable factors can help optimize egg quality including maintaining a healthy BMI, avoiding oxidative stress, and considering omega-3 fatty acid supplementation.

Age-Related Factors

• Female age is the most critical predictor of egg quality, with a significant decline observed in women over 40 years of age, primarily related to deteriorating oocyte quality 1
• Advanced paternal age (40 years and above) can have a synergistic negative effect on egg quality and fertility outcomes, particularly when the female partner is over 35 years 1
• Oxidative stress-induced mitochondrial DNA damage and nuclear DNA damage increases with age in both men and women, potentially affecting egg quality 1

Body Weight and Composition

• Studies on BMI's influence on egg quality show contradictory results, but evidence suggests that both underweight and obese BMI may negatively impact fertility 1
• In IVF studies, increased female and male BMI (both independently and combined) has been shown to negatively influence live birth rates in some studies, while others show no effect 1
• Women with obesity may require higher doses of fertility medications, though once properly adjusted, success rates can be comparable to those with normal weight 1

Nutritional Factors

• Omega-3 fatty acids appear to improve egg quality and may delay ovarian aging, while diets rich in omega-6 fatty acids are associated with poorer reproductive outcomes at advanced maternal age 2
• Even short-term dietary intervention with omega-3 fatty acids initiated at the time of normal age-related reproductive decline may improve oocyte quality 2

Ovarian Reserve and Diminished Ovarian Reserve (DOR)

• Young women with DOR have fewer eggs and embryos but can still achieve good clinical pregnancy rates once eggs are acquired 3
• The miscarriage rate in young women with DOR (19.17%) is significantly higher than in young women with normal ovarian reserve but lower than in older women with DOR (33.90%) 3

Lifestyle Factors

• Current smoking is directly related to infertility and can negatively impact egg quality 4
• Protective effects for fertility have been associated with regular gynecological care, including annual Pap smears 4

Ultrasound Parameters and Endometrial Factors

• Ultrasound parameters can provide important information on egg quality and endometrial receptivity, though robust evidence is still lacking 1
• Endometrial thickness is an important factor in predicting endometrial receptivity, which affects implantation success, though it may not be a good prognostic factor for IUI treatment success 1

Fertility Preservation Techniques

• For women concerned about age-related decline in egg quality, oocyte vitrification (freezing) shows promising results with live birth rates of 50% in women ≤35 years and 22.9% in women >36 years 1
• Success rates with vitrified oocytes are comparable to those achieved with fresh oocytes 1
• The cumulative live birth rate increases with the number of oocytes preserved and is higher in younger women 1

Practical Recommendations for Optimizing Egg Quality

• Consider age as the primary factor - women should be counseled about the significant decline in egg quality after age 35 1
• Maintain a healthy BMI - both underweight and obesity can negatively impact fertility 1
• Avoid smoking, as it directly impacts fertility and egg quality 4
• Consider omega-3 fatty acid supplementation, especially for women of advanced maternal age 2
• For women wishing to delay childbearing, oocyte cryopreservation before age 35 offers the best outcomes 1
• Regular gynecological care may have protective effects on fertility 4

Caveats and Common Pitfalls

• Despite improvements in fertility preservation techniques, success rates are still highly dependent on the woman's age at the time of egg retrieval 1
• Fertility preservation outcomes reported in the literature often come from patients with good prognosis managed by highly experienced teams and may not be representative of all programs 1
• Many women may still believe that eggs contain too much cholesterol and limit consumption, despite changes in dietary guidelines 5, 6, but this is unrelated to egg quality for fertility (this refers to dietary eggs, not human oocytes)
• The effectiveness of GnRH agonists for fertility preservation remains controversial and is not considered an effective method 1