According to a recent study published in the Multidisciplinary Digital Publishing Institute's (MDPI) Nutrients journal, it is possible that a Mediterranean diet can improve fertility. There are many causes of infertility. In women, ovulation disorders and endometriosis are a couple of them, as Mayo Clinic explains, and both of these ailments can be caused by the same factor — inflammation. The National Library of Medicine claims inflammation can affect ovulation and hormone production as well as be associated with endometriosis. Inflammation can also lead to poor sperm quality in men, which is one of the causes of male infertility. The diet incorporates many anti-inflammatory foods that include olive oil, tomatoes, nuts, green leafy vegetables, fruits, and fatty fish. This contributes to a healthy regular menstrual cycle while improving the quality of embryos in women and sperm in men. In addition, it reinforces assisted reproductive technology, such as in vitro fertilization, and has a positive effect on endometriosis.
Inflammation can lead to infertility in both men and women, but the Mediterranean diet can improve fertility, due to the anti-inflammatory composition of the foods it contains. Therefore, it is recommended to be included in the diet of couples that are trying to conceive. However, it may not improve fertility for all couples, since there are various other causes of infertility.
Ref:
https://www.mdpi.com/2072-6643/14/19/3914 
