Egg quality is basically in constant change depending on what you feed your body and the nourishment you get and how well you absorb nutrients (even if you’re over 35, you can conceive healthily, or if you’re under 30 you might have it harder to support a pregnancy, age is not always the reason, but rather your health).
Your body’s metabolism is armed with a process that creates free radicals. Free radicals are also the result of environmental stimuli such as air pollution, smoking, alcohol consumption, chemical and toxic exposure, or excess intake of the wrong foods. If your exposure to any of these stimuli is high or frequent, your body will increase its oxidative stress which will lead to damaged eggs and poor sperm health.
The oxidative stress is known to damage the energy source in our body’s cells (aka mitochondria). When mitochondria is damaged – it provokes even a higher release of oxidation – causing even further and more continuous damage.
Eggs have 10x more mitochondria than any cell in the female human body – meaning that eggs need a lot of energy and increased protection from oxidative stress for a proper and increased rates of egg development and embryo survival.
If you put limits to that source of energy (low calorie diets or simply lowering your calories out of a sudden before pregnancy) will increase the chances of chromosomal abnormalities due to DNA damage in the developing egg – ending in possible miscarriage if fertilised.
Simply put: Poor diet/low calorie/restrictive = poor egg quality = increased oxidative stress = DNA damage = higher chance of miscarriage or infertility.
It takes about 3-4 months for DNA damage or egg improvement to occur before the ovulation you had at (wished) conception time. There is a very high amount of energy needed for an egg to process chromosomes and reach maturity. Mitochondria change constantly in response to nutrients and lifestyle (as well as age as nutrients absorb worse after some time).
The human body is magnificent: the ovarian follicles naturally provide with an anti oxidative defence system, however it can be shut down in cases of infertility, PCOS or ageing.