Higher rates of pregnancy, live birth linked to diet
by Kristen Monaco, Staff Writer, MedPage Today
January 29, 2018
A Mediterranean diet may help improve success of in vitro fertilization (IVF), Greek researchers suggested.
Lower rates of pregnancy (29.1% versus 50.0%, P=0.01) and live births (26.6% versus 48.8%, P=0.01) were seen among with the lowest compliance to the Mediterranean diet when compared with women with the highest compliance, according to Dimitrios Karayiannis, PhD, of Harokopio University in Athens, and colleagues.
Similarly, women with the lowest adherence the diet had a 65% lower relative risk for both pregnancy (RR 0.35, 95% CI 0.16-0.78) and live birth (RR 0.32, 95% CI 0.14-0.71) compared with women with the highest compliance to the diet (P=0.01 for trend for both), they wrote in Human Reproduction.
“Several recent reports have suggested that preconception dietary habits may influence IVF outcome, but most of the work on this topic has focused on the role of isolated nutrients or food groups,” co-authors Nikos Yiannakouris, PhD, and Meropi D. Kontogianni, PhD, also of Harokopio University, jointly told MedPage Today in an email.
“We believe that dietary assessment should be evaluated in a more holistic approach studying dietary patterns instead of single nutrients and/or foods, and given that Mediterranean diet seems to be a very promising and widely accepted pattern with anti-inflammatory and anti-oxidant properties, we decided to focus on potential associations between MedDiet and IVF clinical outcomes among nonobese women of infertile couples attempting fertility,” they added.
The study enrolled 244 Greek women of normal weight (BMI <30) who underwent their first IVF treatment using their own oocytes. Exclusion criteria were prior pregnancy or IVF attempt, endometriosis, diabetes, cardiovascular disease or hypertension, prior ovarian surgery, and history of hypothyroidism, among others.
A self-reported 76-item food-frequency questionnaire was used to collect dietary data for the 6 months prior to the IVF attempt. The questionnaires’ were then used to determine each individual’s MedDiet Score, which were also calculated for male partners.
Successful implantation of an embryo was defined in the analysis as a serum β-hCG level >20 IU/l, 2-3 weeks after oocyte retrieval. A clinical pregnancy was defined was a pregnancy that was confirmed with an ultrasound at 6 weeks gestations, while live birth was defined as the birth ≥24 weeks of gestation.
Across the three tertiles of Mediterranean diet compliance — low, medium, and high — women were generally evenly distributed in regards to income levels, education level, polycystic ovary syndrome status, duration of infertility, and quality of embryos. However, unexplained infertility was more common in women with the highest compliance to the diet. MedDietScore of male partners similarly reflected levels of their partners.
Although not reaching significance, there was a trend towards an increased percentage of successful implantation from IVF tied to a highest adherence to the diet.
Supplement use was also strongly correlated to adherence of the Mediterranean diet, which included use of multivitamins, folate, vitamin C, and other supplements. Due to this, the researchers conducted a sensitivity analysis only including women who did not report any use of supplements (n=132), which found congruent results to the total cohort.
Other study outcomes — ovarian stimulation outcomes, fertilization rate, and embryo quality measures — did not have any notable differences in relation to diet adherence.
The relationship between Mediterranean diet adherence and rates success following IVF were mediated by the woman’s age, however, with a high diet scores only tied to pregnancy and live birth in women who age <35.
Antioxidants may be one plausible explanation for this relationship, the group suggested. “The MedDiet is rich in antioxidants due to the high consumption of fruit, vegetables and whole grains. Recent data suggest that oxidative stress and low antioxidant status may lead to known or unexplained infertility.” However, they noted that prior studies have shown no notable relationship between antioxidant supplements on fertility outcomes.
“We wish with future studies to explore potential underlying mechanisms that could be responsible for the findings of the present study, and in addition to test whether or not advice to adhere more closely to Mediterranean diet would improve assisted reproduction performance,” Yiannakouris and Kontogianni concluded.
The study was supported by Harokopio University. None of the authors reported any conflicts of interest.
Karayiannis and co-authors disclosed no relevant relationships with industry.
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